Development of the Canadian Syncope Risk Score to predict serious adverse events after emergency department assessment of syncope

Utility of serial troponin testing for emergency department patients with syncope

BACKGROUND

For emergency department (ED) patients with syncope, cardiac troponin can identify acute coronary syndrome (ACS) and prognosticate for 30-day serious adverse events. However, it is unclear if serial testing improves diagnostic yield and prognostication.

METHODS

This was a secondary analysis of data from two prospective studies conducted to develop the Canadian Syncope Risk Score. Adults (age ≥ 16 years) with syncope were enrolled, and patient characteristics, vital signs, physician diagnostic impression, electrocardiogram and troponin results, and adjudicated 30-day serious adverse event were collected. The primary outcome was the detection of a serious adverse event within 30 days of ED disposition. The secondary outcome was comparison of ED length of stay among patients with single versus serial troponin measurements.

RESULTS

4996 patients [mean age 64.5 (SD 18.8) years, 52.2% male] were included: 4397 (89.8%) with single troponin [232 (5.3%) with serious adverse event in the ED and 203 (4.6%) after ED disposition]; 499 (10.2%) patients with > 1 troponin measurement [39 (7.8%) with serious adverse event in ED and 60 (12.0%) after ED disposition]. Among those with serial measurements, 10 patients (2.0%) had a rise from below to above the 99th percentile threshold, of whom 4 patients (0.8%) suffered serious adverse event: two with arrhythmias diagnosed on electrocardiogram, one with ACS and one suffered respiratory failure. Nine patients (1.8%) had Canadian Syncope Risk Score risk reclassification based on serial measurement, and none suffered 30-day serious adverse event. Median ED length of stay was significantly longer for patients with serial testing (5.6 vs. 3.8 h, p < 0.001).

CONCLUSIONS

The initial troponin measurement was sufficient for serious adverse event detection and in-ED risk stratification. Serial troponin testing does not improve the diagnostic yield or prognostication and should be reserved for patients with ongoing symptoms or electrocardiogram findings suggestive of cardiac ischemia.

Assessing the Predictive Value of Combining Risk Scoring Systems and Ultrasonography for Short-Term Adverse Outcomes in Syncope: A Prospective Observational Study

BACKGROUND

In the emergency department (ED), the role of ultrasonography (USG) in risk stratification and predicting adverse events in syncope patients is a current research area. However, it is still unclear how ultrasound can be combined with existing risk scores.

OBJECTIVES

In this study, it was aimed to examine the contribution of the use of bedside USG to current risk scores in the evaluation of patients presenting to the ED with syncope. The predictive values of the combined use of USG and risk scores for adverse outcomes at 7 and 30 days were examined.

METHODS

The Canadian Syncope Risk Score (CSRS), San Francisco syncope rules (SFSR), USG findings of carotid and deep venous structures, and echocardiography results were recorded for patients presenting with syncope. Parameters showing significance in the 7-day and 30-day adverse outcome groups were utilized to create new scores termed CSRS-USG and SFSR-USG. Predictive values were evaluated using receiver operating characteristic (ROC) analysis. The difference between the predictive values was evaluated with the DeLong test.

RESULTS

The study was carried out with 137 participants. Adverse outcomes were observed in 45 participants (32.8%) within 30 days. 32 (71.7%) of the adverse outcomes were in the first 7 days. For 30-day adverse outcomes, the SFSR-USG (p = 0.001) and CSRS-USG (p = 0.038) scores had better predictive accuracy compared to SFSR and CSRS, respectively. However, there was no significant improvement in sensitivity and specificity values.

CONCLUSION

The use of USG in the evaluation of syncope patients did not result in significant improvement in sensitivity and specificity values for predicting adverse events. However, larger sample-sized studies are needed to understand its potential contributions better.

Artificial Intelligence-Enabled Electrocardiography Predicts Future Pacemaker Implantation and Adverse Cardiovascular Events

Medical advances prolonging life have led to more permanent pacemaker implants. When pacemaker implantation (PMI) is commonly caused by sick sinus syndrome or conduction disorders, predicting PMI is challenging, as patients often experience related symptoms. This study was designed to create a deep learning model (DLM) for predicting future PMI from ECG data and assess its ability to predict future cardiovascular events. In this study, a DLM was trained on a dataset of 158,471 ECGs from 42,903 academic medical center patients, with additional validation involving 25,640 medical center patients and 26,538 community hospital patients. Primary analysis focused on predicting PMI within 90 days, while all-cause mortality, cardiovascular disease (CVD) mortality, and the development of various cardiovascular conditions were addressed with secondary analysis. The study's raw ECG DLM achieved area under the curve (AUC) values of 0.870, 0.878, and 0.883 for PMI prediction within 30, 60, and 90 days, respectively, along with sensitivities exceeding 82.0% and specificities over 81.9% in the internal validation. Significant ECG features included the PR interval, corrected QT interval, heart rate, QRS duration, P-wave axis, T-wave axis, and QRS complex axis. The AI-predicted PMI group had higher risks of PMI after 90 days (hazard ratio [HR]: 7.49, 95% CI: 5.40-10.39), all-cause mortality (HR: 1.91, 95% CI: 1.74-2.10), CVD mortality (HR: 3.53, 95% CI: 2.73-4.57), and new-onset adverse cardiovascular events. External validation confirmed the model's accuracy. Through ECG analyses, our AI DLM can alert clinicians and patients to the possibility of future PMI and related mortality and cardiovascular risks, aiding in timely patient intervention.

The wolf in sheep's clothing: vasovagal syncope in acute aortic dissection

BACKGROUND

The presentation of acute aortic dissection can pose a challenge for emergency physicians, as it may occur without pain. Atypical presentations can lead to significant delays in diagnosis and increased mortality rates.

CASE DESCRIPTION

Our case illustrates that isolated painless syncope can be a rare presenting symptom of acute aortic dissection type A. What is unique about our case is the limited extension of the dissection tear and the availability of Holter monitoring during the syncopal episode.

CONCLUSION

This constellation provides insight into the pathophysiological mechanism of the syncope in this patient. Mechanisms of syncope related to acute aortic dissection are diverse. We show that vasovagal activation not related to pain can be the underlying mechanism of syncope in acute aortic dissection type A. Although excessive vasovagal tone in the setting of aortic dissection has been hypothesized in the past, it has never been as clearly illustrated as in the present case. This also highlights the challenge in risk stratification of syncope in the emergency department.

Predicting the Outcomes of Inpatient Cardiac Evaluation for Syncope Using Validated Risk Scores

BACKGROUND

Validated syncope risk scores were aimed to predict a cardiac etiology and are mainly used in the decision of hospital admission. Whether these scores could also predict the outcomes of inpatient cardiac evaluation is unknown and was the subject of our study.

METHODS

This was an observational study including consecutive patients admitted for syncope evaluation. All patients completed prolonged electrocardiogram monitoring and an echocardiography before discharge. The area under the receiver-operating characteristic curve (AUC) was used to evaluate the ability of validated risk scores to predict positive inpatient findings. Subsequently, a multivariate regression was performed to identify independent predictors for positive cardiac evaluation, which were then incorporated into the best predictive risk scores.

RESULTS

Three hundred ninety-seven patients were included, 56 (14%) with a positive inpatient cardiac evaluation. The Osservatorio Epidemiologico sulla Sincope Lazio and Canadian Syncope Risk Score achieved the largest AUC (0.701, 95% confidence interval [CI] 0.63-0.77 and 0.694, 95% CI 0.62-0.77, respectively). Yet, all scores provided relatively high sensitivity with low specificity. Multivariate regression revealed age ≥75 (adjusted odds ratio 3.50, 95% CI 1.5-7.9) and abnormal cardiac auscultation (adjusted odds ratio 4.79, 95% CI 2.5-9.1) to be independent predictors. Incorporating these factors led to a significantly higher prediction ability of the Osservatorio Epidemiologico sulla Sincope Lazio (AUC of 0.787, P < .01) and Canadian Syncope Risk Score (AUC 0.778, P < .01) modified scores.

CONCLUSIONS

Current syncope risk scores provide limited prediction ability for the outcomes of inpatient cardiac syncope work-up. One should specifically consider age > 75 years and either cardiac murmur or irregular heart rate on examination very significant in implying a cardiac etiology for syncope. Although these factors may be obvious, current risk scores can be interpreted in such a fashion that ignores the importance of findings extracted from a good history and physical examination.

Role of Artificial Intelligence in Improving Syncope Management

Syncope is common in the general population and a common presenting symptom in acute care settings. Substantial costs are attributed to the care of patients with syncope. Current challenges include differentiating syncope from its mimickers, identifying serious underlying conditions that caused the syncope, and wide variations in current management. Although validated risk tools exist, especially for short-term prognosis, there is inconsistent application, and the current approach does not meet patient needs and expectations. Artificial intelligence (AI) techniques, such as machine learning methods including natural language processing, can potentially address the current challenges in syncope management. Preliminary evidence from published studies indicates that it is possible to accurately differentiate syncope from its mimickers and predict short-term prognosis and hospitalisation. More recently, AI analysis of electrocardiograms has shown promise in detection of serious structural and functional cardiac abnormalities, which has the potential to improve syncope care. Future AI studies have the potential to address current issues in syncope management. AI can automatically prognosticate risk in real time by accessing traditional and nontraditional data. However, steps to mitigate known problems such as generalisability, patient privacy, data protection, and liability will be needed. In the past AI has had limited impact due to underdeveloped analytical methods, lack of computing power, poor access to powerful computing systems, and availability of reliable high-quality data. All impediments except data have been solved. AI will live up to its promise to transform syncope care if the health care system can satisfy AI requirement of large scale, robust, accurate, and reliable data.

Syncope in the Emergency Department: A Practical Approach

Syncope is a common condition encountered in the emergency department (ED), accounting for about 0.6-3% of all ED visits. Despite its high frequency, a widely accepted management strategy for patients with syncope in the ED is still missing. Since syncope can be the presenting condition of many diseases, both severe and benign, most research efforts have focused on strategies to obtain a definitive etiologic diagnosis. Nevertheless, in everyday clinical practice, a definitive diagnosis is rarely reached after the first evaluation. It is thus troublesome to aid clinicians' reasoning by simply focusing on differential diagnoses. With the current review, we would like to propose a management strategy that guides clinicians both in the identification of conditions that warrant immediate treatment and in the management of patients for whom a diagnosis is not immediately reached, differentiating those that can be safely discharged from those that should be admitted to the hospital or monitored before a final decision. We propose the mnemonic acronym RED-SOS: Recognize syncope; Exclude life-threatening conditions; Diagnose; Stratify the risk of adverse events; Observe; decide on the Setting of care. Based on this acronym, in the different sections of the review, we discuss all the elements that clinicians should consider when assessing patients with syncope.

Management of syncope in the Emergency Department: a European prospective cohort study (SEED)

BACKGROUND AND IMPORTANCE

In 2018, the European Society of Cardiology (ESC) produced syncope guidelines that for the first-time incorporated Emergency Department (ED) management. However, very little is known about the characteristics and management of this patient group across Europe.

OBJECTIVES

To examine the prevalence, clinical presentation, assessment, investigation (ECG and laboratory testing), management and ESC and Canadian Syncope Risk Score (CSRS) categories of adult European ED patients presenting with transient loss of consciousness (TLOC, undifferentiated or suspected syncope).

DESIGN

Prospective, multicentre, observational cohort study.

SETTINGS AND PARTICIPANTS

Adults (≥18 years) presenting to European EDs with TLOC, either undifferentiated or thought to be of syncopal origin.

MAIN RESULTS

Between 00:01 Monday, September 12th to 23:59 Sunday 25 September 2022, 952 patients presenting to 41 EDs in 14 European countries were enrolled from 98 301 ED presentations (n = 40 sites). Mean age (SD) was 60.7 (21.7) years and 487 participants were male (51.2%). In total, 379 (39.8%) were admitted to hospital and 573 (60.2%) were discharged. 271 (28.5%) were admitted to an observation unit first with 143 (52.8%) of these being admitted from this. 717 (75.3%) participants were high-risk according to ESC guidelines (and not suitable for discharge from ED) and 235 (24.7%) were low risk. Admission rate increased with increasing ESC high-risk factors; 1 ESC high-risk factor; n = 259 (27.2%, admission rate=34.7%), 2; 189 (19.9%; 38.6%), 3; 106 (11.1%, 54.7%, 4; 62 (6.5%, 60.4%), 5; 48 (5.0%, 67.9%, 6+; 53 (5.6%, 67.9%). Furthermore, 660 (69.3%), 250 (26.3%), 34 (3.5%) and 8 (0.8%) participants had a low, medium, high, and very high CSRS respectively with respective admission rates of 31.4%, 56.0%, 76.5% and 75.0%. Admission rates (19.3-88.9%), use of an observation/decision unit (0-100%), and percentage high-risk (64.8-88.9%) varies widely between countries.

CONCLUSION

This European prospective cohort study reported a 1% prevalence of syncope in the ED. 4 in 10 patients are admitted to hospital although there is wide variation between country in syncope management. Three-quarters of patients have ESC high-risk characteristics with admission percentage rising with increasing ESC high-risk factors.

Development and Validation of a Novel Predictive Model for the Early Differentiation of Cardiac and Non-Cardiac Syncope

Background

The diagnosis of cardiac syncope remains a challenge. This study sought to develop and validate a diagnostic model for the early identification of individuals likely to have a cardiac cause.

Methods

877 syncope patients with a determined cause were retrospectively enrolled at a tertiary heart center. They were randomly divided into the training set and validation set at a 7:3 ratio. We analyzed the demographic information, medical history, laboratory tests, electrocardiogram, and echocardiogram by the least absolute shrinkage and selection operator (LASSO) regression for selection of key features. Then a multivariable logistic regression analysis was performed to identify independent predictors and construct a diagnostic model. The receiver operating characteristic curves, area under the curve (AUC), calibration curves, and decision curve analysis were used to evaluate the predictive accuracy and clinical value of this nomogram.

Results

Five independent predictors for cardiac syncope were selected: BMI (OR 1.088; 95% CI 1.022-1.158; P =0.008), chest symptoms preceding syncope (OR 5.251; 95% CI 3.326-8.288; P <0.001), logarithmic NT-proBNP (OR 1.463; 95% CI 1.240-1.727; P <0.001), left ventricular ejection fraction (OR 0.940; 95% CI 0.908-0.973; P <0.001), and abnormal electrocardiogram (OR 6.171; 95% CI 3.966-9.600; P <0.001). Subsequently, a nomogram based on a multivariate logistic regression model was developed and validated, yielding AUC of 0.873 (95% CI 0.845-0.902) and 0.856 (95% CI 0.809-0.903), respectively. The calibration curves showcased the nomogram's reasonable calibration, and the decision curve analysis demonstrated good clinical utility.

Conclusion

A diagnostic tool providing individualized probability predictions for cardiac syncope was developed and validated, which may potentially serve as an effective tool to facilitate early identification of such patients.

Application of five risk stratification tools for syncope in older adults

OBJECTIVE

Treatment of syncope in older adults places a burden on healthcare systems. We used five risk stratification tools to predict short-term adverse outcomes in older patients with syncope.

METHODS

This was a retrospective analysis of patients with syncope (age ≥60 years) in the emergency department of an urban academic hospital. The data were evaluated using the Risk Stratification of Syncope in the Emergency Department (ROSE), San Francisco Syncope Rule (SFSR), FAINT, Canadian Syncope Risk Score (CSRS), and Boston Syncope Criteria (BSC) tools. Sensitivity, specificity, accuracy, positive and negative predictive value (NPV), and positive and negative likelihood ratios of each tool were calculated and compared for adverse events within 1 month.

RESULTS

In total, 221 patients (average age 75.6 years) were analyzed. Fifty-nine patients (26.7%) had experienced an adverse event within 1 month. For the ROSE, SFSR, FAINT, CSRS and BSC tools, sensitivities were 81.3%, 76.3%, 93.2%, 71.2%, and 94.9%, specificities were 88.3%, 87.7%, 56.8%, 71.6%, and 67.3%, and NPVs were 92.9%, 91.0%, 95.8%, 87.2%, and 97.3%, respectively.

CONCLUSION

The five assessed tools could be useful for physicians in screening older patients with syncope for the risk of short-term adverse events, according to the patient's actual situation.

A Hybrid Model for 30-Day Syncope Prognosis Prediction in the Emergency Department

Syncope is a challenging problem in the emergency department (ED) as the available risk prediction tools have suboptimal predictive performances. Predictive models based on machine learning (ML) are promising tools whose application in the context of syncope remains underexplored. The aim of the present study was to develop and compare the performance of ML-based models in predicting the risk of clinically significant outcomes in patients presenting to the ED for syncope. We enrolled 266 consecutive patients (age 73, IQR 58-83; 52% males) admitted for syncope at three tertiary centers. We collected demographic and clinical information as well as the occurrence of clinically significant outcomes at a 30-day telephone follow-up. We implemented an XGBoost model based on the best-performing candidate predictors. Subsequently, we integrated the XGboost predictors with knowledge-based rules. The obtained hybrid model outperformed the XGboost model (AUC = 0.81 vs. 0.73, p < 0.001) with acceptable calibration. In conclusion, we developed an ML-based model characterized by a commendable capability to predict adverse events within 30 days post-syncope evaluation in the ED. This model relies solely on clinical data routinely collected during a patient's initial syncope evaluation, thus obviating the need for laboratory tests or syncope experienced clinical judgment.

Comparison of syncope risk scores in predicting the prognosis of patients presenting to the emergency department with syncope

BACKGROUND

Various scores have been derived for the assessment of syncope patients in the emergency department (ED).

AIM

We aimed to compare the effectiveness of Canadian Syncope Risk Scores (CSRS), San Francisco Syncope Rules (SFSR), and Osservatorio Epidemiologico sulla Sincope nel Lazio (OESIL) risk scores in predicting the risk of major adverse cardiac events (MACE) and mortality among syncope patients within 30 days of the initial ED visit.

METHODS

We performed a prospective, observational case series study of adults (≥ 18 years) with unexplained syncope/near-syncope who presented to ED. Demographic characteristics of the patients and clinical and laboratory data were recorded in the standard data collection form of the study. Our primary outcome was a 30-day mortality.

RESULTS

A total of 421 patients (mean age 50.9 ± 20.8, 51.5% male) were enrolled. The rate of MACE development in the 30-day follow-up of the patients was 12.8% (n = 54). While 20.2% (n = 85) of the patients were hospitalized, two of the patients died in the emergency room and the 30-day mortality was 5.5% (n = 23). CSRS was found to have the highest predictive power of mortality (AUC: 0.869, 95% CI 0.799-0.939, p < 0.001). If the cut-off value of CSRS was 0.5, the sensitivity was found to be 82.6% and the specificity was 81.9%. Also CSRS (OR: 1.402, 95% CI: 1.053-1.867, p = 0.021) was found to be an independent predictor of the 30-day mortality.

CONCLUSION

The CSRS may be used as a safety risk score for a 30-day risk of MACE and mortality after discharge from the emergency department.

Implementation of the Canadian syncope pathway: a pilot non-randomized stepped wedge trial

BACKGROUND

We developed the Canadian Syncope Pathway (CSP) based on the Canadian Syncope Risk Score (CSRS) to aid emergency department (ED) syncope management. This pilot implementation study assessed patient inclusion, length of transition period, as well as process measures (engagement, reach, adoption, and fidelity) to prepare for multicenter implementation.

METHODS

A non-randomized stepped wedge trial at two hospitals was conducted over a 7-month period. After 2-3 months in the control condition, the hospitals crossed over in a stepwise fashion to the intervention condition. Study participants were ED and non-ED physicians, or their delegates, and patients (aged ≥ 18 years) with syncope. We aimed to analyze patient characteristics, ED management including disposition decision, and CSRS recommendations application for all eligible patients during the intervention period. Our targets were 95% inclusion rate, 70% adoption (proportion of physicians who applied the pathway), 60% reach (intervention applied to eligible patients) and 70% fidelity (appropriate recommendations application) for all eligible patients. Clinical Trials registration NCT04790058.

RESULTS

1002 eligible patients (mean age 56.6 years; 51.0% males) were included: 349 patients during the control and 653 patients during the intervention period. Physician engagement varied from 39.7% to 97.1% for presentation at meetings. Process measures for the first month and the end of the intervention were: adoption 70.7% (58/82) and 84.4% (103/122), reach 67.5% (108/160) and 55.0% (359/653), fidelity among patients with physician data form completion 86.3% (88/102) and 88.3% (294/333), versus fidelity among all eligible patients 83.8% (134/160) and 83.3% (544/653) respectively with no significant differences in fidelity at one month and the end of the intervention period.

CONCLUSION

In this pilot study, we achieved all prespecified benchmarks for proceeding to the multicenter CSP implementation except reach. Our results indicate a 1-month transition period will be adequate though regular reminders will be needed during full-scale implementation.

Performance of high-sensitivity cardiac troponin T in predicting major cardiovascular events in patients admitted to the emergency department for syncope with normal ECG: An observational prospective study

INTRODUCTION

History of syncope, clinical examination and electrocardiographic (ECG) findings are fundamental to assess the risk of major cardiovascular events (MACE) in patients attending the emergency department (ED) for syncope. However, in the absence of abnormal clinical examination findings or an abnormal ECG in the ED, transient rhythm or conduction disorders may not be safely excluded, hence predicting MACE remains challenging. High-sensitivity cardiac troponin T (hs-cTnT) may be a useful tool in this context.

AIM

The primary objective was to evaluate the performance of hs-cTnT in the diagnosis of MACE at 30 days in patients attending the ED for syncope with a normal initial ECG.

METHODS

This was a prospective observational cohort study that took place in the ED of a French university hospital between June 2018 and June 2019. Patients≥18 years admitted to the ED for syncope with a normal ECG were eligible. After receiving verbal consent from patients, the ED physician collected clinical and ECG data and all patients had a blood sample taken that included hs-cTnT measurement. The primary outcome was MACE within 30 days after the ED visit. MACE were evaluated by consulting the patient's medical records and telephoning patients or their general practitioners. Sensitivity, specificity, positive and negative predictive values were calculated with their 95% confidence intervals (CI) for different hs-cTnT thresholds.

RESULTS

Data from 246 patients were analysed, including 21 (9%) with MACE. Hs-cTnT had an area under the curve of 0.917 (CI: 0.872-0.962). Hs-cTnT with a threshold of 19ng/L had a sensitivity of 86% (CI: 64-97) and a specificity of 86% (CI: 81-90) for predicting MACE.

CONCLUSION

Hs-cTnT may be a relevant tool for assessing MACE risk in patients with syncope and normal ECG results.

Risk stratification tools for patients with syncope in emergency medical services and emergency departments: a scoping review

BACKGROUND

Patients with a syncope constitute a challenge for risk stratification in (prehospital) emergency care. Professionals in EMS and ED need to differentiate the high-risk from the low-risk syncope patient, with limited time and resources. Clinical decision rules (CDRs) are designed to support professionals in risk stratification and clinical decision-making. Current CDRs seem unable to meet the standards to be used in the chain of emergency care. However, the need for a structured approach for syncope patients remains. We aimed to generate a broad overview of the available risk stratification tools and identify key elements, scoring systems and measurement properties of these tools.

METHODS

We performed a scoping review with a literature search in MEDLINE, CINAHL, Pubmed, Embase, Cochrane and Web of Science from January 2010 to May 2022. Study selection was done by two researchers independently and was supervised by a third researcher. Data extraction was performed through a data extraction form, and data were summarised through descriptive synthesis. A quality assessment of included studies was performed using a generic quality assessment tool for quantitative research and the AMSTAR-2 for systematic reviews.

RESULTS

The literature search identified 5385 unique studies; 38 were included in the review. We discovered 19 risk stratification tools, one of which was established in EMS patient care. One-third of risk stratification tools have been validated. Two main approaches for the application of the tools were identified. Elements of the tools were categorised in history taking, physical examination, electrocardiogram, additional examinations and other variables. Evaluation of measurement properties showed that negative and positive predictive value was used in half of the studies to assess the accuracy of tools.

CONCLUSION

A total of 19 risk stratification tools for syncope patients were identified. They were primarily established in ED patient care; most are not validated properly. Key elements in the risk stratification related to a potential cardiac problem as cause for the syncope. These insights provide directions for the key elements of a risk stratification tool and for a more advanced process to validate risk stratification tools.

Developing Implementation Strategies to Support the Uptake of a Risk Tool to Aid Physicians in the Clinical Management of Patients With Syncope: Systematic Theoretical and User-Centered Design Approach

BACKGROUND

The Canadian Syncope Risk Score (CSRS) was developed to improve syncope management in emergency department settings. Evidence-based tools often fail to have the intended impact because of suboptimal uptake or poor implementation.

OBJECTIVE

In this paper, we aimed to describe the process of developing evidence-based implementation strategies to support the deployment and use of the CSRS in real-world emergency department settings to improve syncope management among physicians.

METHODS

We followed a systematic approach for intervention development, including identifying who needs to do what differently, identifying the barriers and enablers to be addressed, and identifying the intervention components and modes of delivery to overcome the identified barriers. We used the Behaviour Change Wheel to guide the selection of implementation strategies. We engaged CSRS end users (ie, emergency medicine physicians) in a user-centered design approach to generate and refine strategies. This was achieved over a series of 3 qualitative user-centered design workshops lasting 90 minutes each with 3 groups of emergency medicine physicians.

RESULTS

A total of 14 physicians participated in the workshops. The themes were organized according to the following intervention development steps: theme 1-identifying and refining barriers and theme 2-identifying the intervention components and modes of delivery. Theme 2 was subdivided into two subthemes: (1) generating high-level strategies and developing strategies prototypes and (2) refining and testing strategies. The main strategies identified to overcome barriers included education in the format of meetings, videos, journal clubs, and posters (to address uncertainty around when and how to apply the CSRS); the development of a web-based calculator and integration into the electronic medical record (to address uncertainty in how to apply the CSRS); a local champion (to address the lack of team buy-in); and the dissemination of evidence summaries and feedback through email communications (to address a lack of evidence about impact).

CONCLUSIONS

The ability of the CSRS to effectively improve patient safety and syncope management relies on broad buy-in and uptake across physicians. To ensure that the CSRS is well positioned for impact, a comprehensive suite of strategies was identified to address known barriers.

Arrhythmic syncope: From diagnosis to management

Syncope is a concerning symptom that affects a large proportion of patients. It can be related to a heterogeneous group of pathologies ranging from trivial causes to diseases with a high risk of sudden death. However, benign causes are the most frequent, and identifying high-risk patients with potentially severe etiologies is crucial to establish an accurate diagnosis, initiate effective therapy, and alter the prognosis. The term cardiac syncope refers to those episodes where the cause of the cerebral hypoperfusion is directly related to a cardiac disorder, while arrhythmic syncope is cardiac syncope specifically due to rhythm disorders. Indeed, arrhythmias are the most common cause of cardiac syncope. Both bradyarrhythmia and tachyarrhythmia can cause a sudden decrease in cardiac output and produce syncope. In this review, we summarized the main guidelines in the management of patients with syncope of presumed arrhythmic origin. Therefore, we presented a thorough approach to syncope work-up through different tests depending on the clinical characteristics of the patients, risk stratification, and the management of syncope in different scenarios such as structural heart disease and channelopathies.

Development of practice recommendations based on the Canadian Syncope Risk Score and identification of barriers and facilitators for implementation

BACKGROUND

Wide variations in emergency department (ED) syncope management exist. The Canadian Syncope Risk Score (CSRS) was developed to predict the probability of 30-day serious outcomes after ED disposition. Study objectives were to evaluate the acceptability of proposed CSRS practice recommendations among providers and patients, and identify barriers and facilitators for CSRS use to guide disposition decisions.

METHODS

We conducted semi-structured interviews with 41 physicians involved in ED syncope and 35 ED patients with syncope. We used purposive sampling to ensure a variety of physician specialties and CSRS patient risk levels. Thematic analysis was completed by two independent coders with consensus meetings to resolve conflicts. Analysis proceeded in parallel with interviews until data saturation.

RESULTS

The majority (97.6%; 40/41) of physicians agreed with discharge of low risk (CSRS ≤ 0) but opined that 'no follow up' changed to 'follow-up as needed'. Physicians indicated current practices do not align with the medium-risk recommendation to discharge patients with 15-day monitoring (CSRS = 1-3; due to lack of access to monitors and timely follow-up) and the high-risk recommendation (CSRS ≥ 4) to potentially discharge patients with 15-day monitoring. Physicians recommended brief hospitalization of high-risk patients due to patient safety concerns. Facilitators included the CSRS-based patient education and scores supporting their clinical gestalt. Patients reported receiving varying levels of information regarding syncope and post-ED care, were satisfied with care received and preferred less resource intensive options.

CONCLUSION

Our recommendations based on the study results were: discharge of low-risk patients with physician follow-up as needed; discharge of medium-risk patients with 15-day cardiac monitoring and brief hospitalization of high-risk patients with 15-day cardiac monitoring if discharged. Patients preferred less resource intensive options, in line with CSRS recommended care. Implementation should leverage identified facilitators (e.g., patient education) and address the barriers (e.g., monitor access) to improve ED syncope care.

Predicting short-term adverse outcomes in the geriatric population presenting with syncope: a comparison of existing syncope rules and beyond

OBJECTIVES

Syncope at age 65+ is associated with increased mortality, irrespective of cause. Syncope rules were designed to aid in risk-stratification but were only validated in the general adult population. Our objective was to determine if they can be applied to a geriatric population in predicting short-term adverse outcomes.

METHODS

In this single-center retrospective study, we evaluated 350 patients aged 65+ presenting with syncope. Exclusion criteria included confirmed non-syncope, active medical condition, drug or alcohol-related syncope. Patients were stratified into high or low risk based on Canadian Syncope Risk Score (CSRS), Evaluation of Guidelines in Syncope Study (EGSYS), San Francisco Syncope Rule (SFSR), and Risk Stratification of Syncope in the Emergency Department (ROSE). Composite adverse outcomes at 48-hour and 30-day included all-cause mortality, major adverse cardiac and cerebrovascular events (MACCE), return emergency department visit, hospitalization, or medical intervention. We assessed each score's ability to predict the outcomes using logistic-regression and compared performances using receiver-operator curves. Multivariate analyses were performed to study the associations between recorded parameters and outcomes.

RESULTS

CSRS outperformed with AUC of 0.732 (95% CI: 0.653-0.812) and 0.749 (95% CI: 0.688-0.809) for 48-h and 30-day outcomes, respectively. Sensitivities for CSRS, EGSYS, SFSR, and ROSE for 48-hour outcomes were 48%, 65%, 42% and 19%; and for 30-day outcomes were 72%, 65%, 30% and 55%, respectively. Atrial fibrillation/flutter on EKG, congestive heart failure, antiarrhythmics, systolic blood-pressure < 90 at triage, and associated chest pain highly correlated with 48-h outcomes. An EKG abnormality, heart disease history, severe pulmonary hypertension, BNP > 300, vasovagal predisposition, and antidepressants highly correlated with 30-day outcomes.

CONCLUSIONS

Performance and accuracy of four prominent syncope rules were suboptimal in identifying high-risk geriatric patients with short-term adverse outcomes. We identified some significant clinical and laboratory information that may play a role in predicting short-term adverse events in a geriatric cohort.

Arrhythmic risk in single or recurrent episodes of unexplained syncope with complete bundle branch block

INTRODUCTION AND OBJECTIVES

Patients with a single syncopal episode (SSE) and complete bundle branch block (cBBB) are frequently managed more conservatively than patients with recurrent episodes (RSE). The objective of this study was to analyze if there are differences between patients with single or recurrent unexplained syncope and cBBB in arrhythmic risk, the diagnostic yield of tests, and clinical outcomes.

METHODS

Cohort study of consecutive patients with unexplained syncope and cBBB with a median follow-up time of 3 years. The patients were evaluated via a stepwise workup protocol based on electrophysiological study (EPS) and long-term follow-up with an implantable cardiac monitor.

RESULTS

Of the 503 patients included in the study, 238 (47.3%) had had only 1 syncopal episode. The risk of an arrhythmic syncope was similar in both groups (58.8% in SSE vs 57.0% in RSE; P=.68), also after adjustment for possible confounding variables (HR, 1.06; 95%CI, 0.81-1.38; P=.674). No significant differences between the groups were found in the EPS results and implantable cardiac monitor diagnostic yield. A total of 141 (59.2%) patients with SSE and 154 (58.1%) patients with RSE required cardiac device implantation (P=.797). After appropriate treatment, 35 (7%) patients had recurrence of syncope. The recurrence rate and mortality were also similar in both groups.

CONCLUSIONS

Patients with cBBB and unexplained syncope are at high risk of an arrhythmic etiology, even after the first syncopal episode. Patients with SSE and RSE have a similar arrhythmic risk and similar outcomes, and therefore there is no clinical justification for not managing them in the same manner.

Economic evaluation of applying the Canadian Syncope Risk Score in an Australian emergency department

OBJECTIVE

To evaluate the Canadian Syncope Risk Score (CSRS) in syncope patients presenting to the ED from an economic perspective, using very-low and low-risk patients (CSRS -3 to 0) as a threshold for avoiding hospital admissions.

METHODS

A decision-analytic model, specifically a decision-tree, was developed to evaluate application of the CSRS. A hypothetical cohort of 1000 patients was modelled based on characteristics and outcome of patients enrolled in a clinical validation study performed alongside this evaluation. Several analytic based approaches were used to handle model outputs and uncertainties.

RESULTS

For a cohort of 1000 patients, applying the CSRS was associated with 169 less inpatient admissions from the ED, when compared to usual care. There was also a cost-saving of $8255 per admitted patient, when the CSRS was applied, compared to usual care. Adopting the CSRS was the optimal approach in all scenario analyses and was robust to changes in model parameters. More than three-quarters (78.6%) of all model simulations showed that applying the CSRS is a cost-saving approach to managing syncope. There was high confidence in all results, with the approach using the CSRS reducing the costs and number of syncope-related hospital admissions.

CONCLUSIONS

Compared to usual care, applying the CSRS appeared as a cost-effective strategy. This new evidence will help decision-makers choose cost-effective approaches for the management of patients presenting to the ED with syncope, as they search for efficient ways to maximise health gain from a finite budget.

e Silva L. Prognostic accuracy of syncope clinical prediction rules in older adults in the emergency department

Study objective

The objective of this study is to evaluate the prognostic accuracy of existing rules (San Francisco Syncope Rule [SFSR], Canadian Syncope Risk Score [CSRS], and FAINT score) in older adults.

Methods

This is a cohort study of adults aged ≥60 years presenting to an academic emergency department (ED) with syncope or near syncope. We used original criteria for all rules except for the FAINT score, in which N‐terminal pro–brain natriuretic peptide was largely missing from the extracted data. Patients were deemed positive for each rule if classified as non‐low risk. The primary outcome was the presence of 30‐day serious outcome, as defined by syncope research guidelines. Sensitivity and negative likelihood ratio (NLR) were calculated with 95% confidence intervals (CIs).

Results

A total of 404 ED visits (mean age of patients, 75.5 years) were included. Of these, 44 (10.9%) had a 30‐day serious outcome, and 24 (5.9%) had incomplete 30‐day follow‐up. SFSR was positive for 280 of 380 visits with complete follow‐up. Its sensitivity and NLR for predicting 30‐day serious outcomes were 86.4% (95% CI, 72.0%–94.3%) and 0.53 (95% CI, 0.25–1.15), respectively. The CSRS was positive for 299 of 380 visits (sensitivity was 88.6% [95% CI, 76.4%–95.7%], and NLR was 0.50 [95% CI, 0.22–1.17]). The modified FAI(N)T score was positive for 318 of 380 visits (sensitivity was 90.9% [95% CI, 77.4%–97.0%], and NLR was 0.53 [95% CI, 0.20–1.38]).

Conclusion

Existing rules are suboptimal to predict 30‐day serious outcomes in older adults presenting with syncope or near syncope to the ED.

Prediction of Pacemaker Requirement in Patients With Unexplained Syncope: The DROP Score

BACKGROUND

Implantable loop recorders (ILR) are increasingly utilised in the evaluation of unexplained syncope. However, they are expensive and do not protect against future syncope.

OBJECTIVES

To compare patients requiring permanent pacemaker (PPM) implantation during ILR follow-up with those without abnormalities detected on ILR in order to identify potential predictors of benefit from upfront pacing.

METHODS

We analysed 100 consecutive patients receiving ILR: Group 1 (n=50) underwent PPM insertion due to bradyarrhythmias detected on ILR; Group 2 (n=50) had no arrhythmias detected on ILR over >3 years follow-up. Baseline clinical characteristics, syncope history, electrocardiographic and echocardiographic parameters were assessed to identify predictors of ultimate requirement for pacing.

RESULTS

Group 1 (64% male, median age 70.8 years; IQR 65.5-78.8) were older than Group 2 (58% male, median 60.2 years; IQR 44.0-73.0 p=0.001) and were less likely to have related historical factors such as overheating, posture and exercise (98% vs 70% p<0.001). PR interval was also longer in Group 1 (192±51 vs 169±23 p=0.006) with greater prevalence of distal conduction system disease (30% vs 4.3% p=0.002). Significant univariate predictors for PPM insertion were distal conduction disease (p=0.007), first degree atrioventricular (AV) block (p=0.003), absence of precipitating factors (p=0.004), and age >65 years (p=0.001). Injury sustained, recurrent syncope, history of atrial fibrillation (AF) or heart failure, left atrial (LA) size and left ventricular ejection fraction (LVEF) were not predictive. These significant predictors were incorporated into the DROP score¹ (0-4). Using time-to-event analysis, no patients with a score of 0 progressed to pacing, while higher scores (3-4) strongly predicted pacing requirement (log-rank p<0.001).

CONCLUSION

The DROP score may be helpful in identifying patients likely to benefit from upfront permanent pacemaker (PPM) insertion following unexplained syncope. Larger prospective studies are required to validate this tool.

Assessment of Canadian Syncope Risk Score in the prediction of outcomes of patients with syncope at the Emergency Department of Suez Canal University: STROBE compliant

Syncope is a temporary loss of consciousness usually related to insufficient blood flow to the brain. It's also called fainting or "passing out." Syncope is responsible for 3% to 5% of emergency department visits, with a hospitalization rate in about 40% of cases, with an average stay of 5.5 days. The Canadian Syncope Risk Score showed good discrimination and calibration for 30-day risk of serious adverse events after disposition from the emergency department.The aim was to assess Canadian Syncope Risk Score in predicting outcomes and mortality at the emergency department of Suez Canal University Hospitals.A prospective observational cohort study was carried out in emergency department in Suez Canal University Hospital. After approval by the Ethical and Research Committee of Faculty of Medicine, Suez Canal University, 60 patients with syncope attending to emergency department were included to this study. All included participants were assessed by history taking and they also assessed by the Canadian Syncope Risk Score.The Canadian Syncope Risk Score's mean of the study group was 4.9 and the range of the scores was from -2 to 11. The mean of the percentage of risk of serious events at 30 days in the study group was 29.17% and it ranged from 0.7% to 83.6%.There was a statistically significant difference between means Canadian Syncope Risk Score's score regarding complication occurrence. Cases which showed complications had a mean score of 7.33 compared to a mean score of 1.25 in case of no complication occurrence P-value <.001. At a cut-off point of more than 3 for the Canadian Syncope Risk Score's, sensitivity of that score in complication's occurrence prediction was 100% and the specificity was 87.5% P-value <.001.The Canadian Syncope Risk Score's is strong predictor for risk of serious adverse events and a good indicator for admission, with 100% sensitivity and 87.5% specificity at cut off point more than 3.

Development of a Novel Emergency Department Quality Measure to Reduce Very Low-Risk Syncope Hospitalizations

STUDY OBJECTIVE

Emergency department (ED) evaluations for syncope are common, representing 1.3 million annual US visits and $2 billion in related hospitalizations. Despite evidence supporting risk stratification and outpatient management, variation in syncope hospitalization rates persist. We sought to develop a new quality measure for very low-risk adult ED patients with syncope that could be applied to administrative data.

METHODS

We developed this quality measure in 2 phases. First, we used an existing prospective, observational ED patient data set to identify a very low-risk cohort with unexplained syncope using 2 variables: age less than 50 years and no history of heart disease. We then applied this to the 2019 Nationwide Emergency Department Sample (NEDS) to assess its potential effect, assessing for hospital-level factors associated with hospitalization variation.

RESULTS

Of the 8,647 adult patients in the prospective cohort, 3,292 (38%) patients fulfilled these 2 criteria: age less than 50 years and no history of heart disease. Of these, 15 (0.46%) suffered serious adverse events within 30 days. In the NEDS, there were an estimated 566,031 patients meeting these 2 criteria, of whom 15,507 (2.7%; 95% confidence interval [CI] 2.48% to 3.00%) were hospitalized. We found substantial variation in the hospitalization rates for this very low-risk cohort, with a median rate of 1.7% (range 0% to 100%; interquartile range 0% to 3.9%). Factors associated with increased hospitalization rates included a yearly ED volume of more than 80,000 (odds ratio [OR] 3.14; 95% CI 2.02 to 4.89) and metropolitan teaching status (OR 1.5; 95% CI 1.24 to 1.81).

CONCLUSION

In summary, our novel syncope quality measure can assess variation in low-value hospitalizations for unexplained syncope. The application of this measure could improve the value of syncope care.

Machine learning versus traditional methods for the development of risk stratification scores: a case study using original Canadian Syncope Risk Score data

Artificial Intelligence and machine learning (ML) methods are promising for risk-stratification, but the added benefit over traditional statistical methods remains unclear. We compared predictive models developed using machine learning (ML) methods to the Canadian Syncope Risk Score (CSRS), a risk-tool developed with logistic regression for predicting serious adverse events (SAE) after emergency department (ED) disposition for syncope. We used the prospective multicenter cohort data collected for CSRS development at 11 Canadian EDs over an 8-year period to develop four ML models to predict 30-day SAE (death, arrhythmias, MI, structural heart disease, pulmonary embolism, hemorrhage) after ED disposition. The CSRS derivation and validation cohorts were used for training and testing, respectively, and the 43 variables used included demographics, medical history, vital signs, ECG findings, blood tests and the diagnostic impression of the emergency physician. Performance was assessed using the area under the receiver-operating-characteristics curve (AUC) and calibration curves. Of the 4030 patients in the training set and 3819 patients in the test set overall, 286 (3.6%) patients suffered 30-day SAE. The AUCs for model validation in test data were CSRS 0.902 (0.877-0.926), regularized regression 0.903 (0.877-0.928), gradient boosting 0.914 (0.894-0.934), deep neural network 0.906 (0.883-0.929), simplified gradient boosting 0.904 (0.881-0.927). The AUCs and calibration slopes for the ML models and CSRS were similar. Two ML models used fewer predictors than the CSRS but matched its performance. Overall, the ML models matched the CSRS in performance, with some models using fewer predictors.

International Validation of the Canadian Syncope Risk Score : A Cohort Study

BACKGROUND

The Canadian Syncope Risk Score (CSRS) was developed to predict 30-day serious outcomes not evident during emergency department (ED) evaluation.

OBJECTIVE

To externally validate the CSRS and compare it with another validated score, the Osservatorio Epidemiologico della Sincope nel Lazio (OESIL) score.

DESIGN

Prospective cohort study.

SETTING

Large, international, multicenter study recruiting patients in EDs in 8 countries on 3 continents.

PARTICIPANTS

Patients with syncope aged 40 years or older presenting to the ED within 12 hours of syncope.

MEASUREMENTS

Composite outcome of serious clinical plus procedural events (primary outcome) and the primary composite outcome excluding procedural interventions (secondary outcome).

RESULTS

Among 2283 patients with a mean age of 68 years, the primary composite outcome occurred in 7.2%, and the composite outcome excluding procedural interventions occurred in 3.1% at 30 days. Prognostic performance of the CSRS was good for both 30-day composite outcomes and better compared with the OESIL score (area under the receiver-operating characteristic curve [AUC], 0.85 [95% CI, 0.83 to 0.88] vs. 0.74 [CI, 0.71 to 0.78] and 0.80 [CI, 0.75 to 0.84] vs. 0.69 [CI, 0.64 to 0.75], respectively). Safety of triage, as measured by the frequency of the primary composite outcome in the low-risk group, was higher using the CSRS (19 of 1388 [0.6%]) versus the OESIL score (17 of 1104 [1.5%]). A simplified model including only the clinician classification of syncope (cardiac syncope, vasovagal syncope, or other) variable at ED discharge-a component of the CSRS-achieved similar discrimination as the CSRS (AUC, 0.83 [CI, 0.80 to 0.87] for the primary composite outcome).

LIMITATION

Unable to disentangle the influence of other CSRS components on clinician classification of syncope at ED discharge.

CONCLUSION

This international external validation of the CSRS showed good performance in identifying patients at low risk for serious outcomes outside of Canada and superior performance compared with the OESIL score. However, clinician classification of syncope at ED discharge seems to explain much of the performance of the CSRS in this study. The clinical utility of the CSRS remains uncertain.

PRIMARY FUNDING SOURCE

Swiss National Science Foundation & Swiss Heart Foundation.

Risk stratification of syncope: Current syncope guidelines and beyond

Syncope is an alarming event carrying the possibility of serious outcomes, including sudden cardiac death (SCD). Therefore, immediate risk stratification should be applied whenever syncope occurs, especially in the Emergency Department, where most dramatic presentations occur. It has long been known that short- and long-term syncope prognosis is affected not only by its mechanism but also by presence of concomitant conditions, especially cardiovascular disease. Over the last two decades, several syncope prediction tools have been developed to refine patient stratification and triage patients who need expert in-hospital care from those who may receive nonurgent expert care in the community. However, despite promising results, prognostic tools for syncope remain challenging and often poorly effective. Current European Society of Cardiology syncope guidelines recommend an initial syncope workup based on detailed patient's history, physical examination supine and standing blood pressure, resting ECG, and laboratory tests, including cardiac biomarkers, where appropriate. Subsequent risk stratification based on screening of features aims to identify three groups: high-, intermediate- and low-risk. The first should immediately be hospitalized and appropriately investigated; intermediate group, with recurrent or medium-risk events, requires systematic evaluation by syncope experts; low-risk group, sporadic reflex syncope, merits education about its benign nature, and discharge. Thus, initial syncope risk stratification is crucial as it determines how and by whom syncope patients are managed. This review summarizes the crucial elements of syncope risk stratification, pros and cons of proposed risk evaluation scores, major challenges in initial syncope management, and how risk stratification impacts management of high-risk/recurrent syncope.

Appropriate use of transthoracic echocardiography in the investigation of general medicine patients presenting with syncope or presyncope

STUDY PURPOSE

Routine transthoracic echocardiography (TTE) in patients with syncope or presyncope is resource-intensive. We assessed if risk thresholds defined by a validated risk score may identify patients at low risk of cardiac abnormality in whom TTE is unnecessary.

STUDY DESIGN

We conducted a retrospective study of all general medicine patients with syncope/presyncope presenting to a tertiary hospital between July 2016 and September 2020 and who underwent TTE. The Canadian Syncope Risk Score (CSRS) was used to categorise patients as low to very low risk (score -3 to 0) or moderate to high risk (score ≥1) for serious adverse events at 30 days. A cut-point of 0 was used to calculate the sensitivity, specificity, positive and negative predictive values (PPV and NPV) for CSRS and the odds ratio (OR) of a clinically significant finding on TTE in patients with CSRS ≥1 compared with all patients.

RESULTS

Among 157 patients, the CSRS categorised 69 (44%) as very low to low risk in whom TTE was normal. In 88 patients deemed moderate to high risk, TTE detected a cardiac abnormality in 24 (27%). A CSRS ≥1 yielded a sensitivity of 100% (95% CI 85.7% to 100%), specificity of 51.1% (95% CI 42.3% to 59.8%), PPV of 26.5% (95% CI 26.3% to 30.1%) and NPV of 100% (95% CI 92.5% to 100%) for cardiac abnormalities and doubled the odds of an abnormality (OR=2.05, 95% CI 1.08 to 3.87, p=0.028).

CONCLUSION

In general medicine patients with syncope/presyncope, using the CSRS to stratify risk of a cardiac abnormality on TTE can almost halve TTE use.

Syncope Prediction Scores in the Emergency Department

Syncope is a common clinical presentation defined as a transient loss of consciousness (TLOC) due to cerebral hypoperfusion, characterized by a rapid onset, short duration, and spontaneous complete recovery. Different clinical decision rules (CDRs) and risk stratification scores have been developed to predict short- and long-term risks for adverse outcomes after syncope. The central theme of these prediction systems is consistent with the ESC syncope guidelines. Initial assessment according to the ESC guideline is essential until an optimal and well-validated risk score is available. The focus should be accurate risk stratification to allow prevention of adverse outcomes and optimize the use of limited healthcare resources. In this review article, we summarize and critically appraise the evidence regarding the CDRs for patients presenting with syncope.

Knowledge translation of prediction rules: methods to help health professionals understand their trade-offs

Clinical prediction models are developed with the ultimate aim of improving patient outcomes, and are often turned into prediction rules (e.g. classifying people as low/high risk using cut-points of predicted risk) at some point during the development stage. Prediction rules often have reasonable ability to either rule-in or rule-out disease (or another event), but rarely both. When a prediction model is intended to be used as a prediction rule, conveying its performance using the C-statistic, the most commonly reported model performance measure, does not provide information on the magnitude of the trade-offs. Yet, it is important that these trade-offs are clear, for example, to health professionals who might implement the prediction rule. This can be viewed as a form of knowledge translation. When communicating information on trade-offs to patients and the public there is a large body of evidence that indicates natural frequencies are most easily understood, and one particularly well-received way of depicting the natural frequency information is to use population diagrams. There is also evidence that health professionals benefit from information presented in this way.Here we illustrate how the implications of the trade-offs associated with prediction rules can be more readily appreciated when using natural frequencies. We recommend that the reporting of the performance of prediction rules should (1) present information using natural frequencies across a range of cut-points to inform the choice of plausible cut-points and (2) when the prediction rule is recommended for clinical use at a particular cut-point the implications of the trade-offs are communicated using population diagrams. Using two existing prediction rules, we illustrate how these methods offer a means of effectively and transparently communicating essential information about trade-offs associated with prediction rules.

The ability of Canadian Syncope risk score in differentiating cardiogenic and non-cardiogenic syncope; a cross-sectional study

INTRODUCTION

Determining the underlying etiology of syncope provides valuable prognostic information and expedites the implementation of a therapeutic strategy. This study aimed to evaluate the ability of Canadian Syncope Risk Score (CSRS) in differentiating cardiogenic and non-cardiac syncope.

METHODS

The present diagnostic accuracy study was conducted on adult patients with syncope, who presented to the emergency departments of Shohadaye Tajrish and Imam Hossein Hospitals in Tehran from March 2018 to March 2019. The data required for determining CSRS were collected during the initial assessment and the underlying etiology was confirmed through further diagnostic follow-up under the supervision of a cardiologist or neurologist. Finally, the screening performance characteristics of the score were calculated.

RESULTS

300 patients with the mean age of 56.38 ± 19.10 years were studied. The source of syncope was cardiac in 133 (44.3%) and non-cardiac in 137 (55.7%) patients. The area under the ROC curve of CSRS in differentiating cardiac syncope was 0.77 (95% CI: 0.715-0.824). At a cutoff point of -1.5, the sensitivity and specificity of the score were calculated to be 73.68% (95% CI: 65.21-80.75%) and 73.05% (95%CI: 75.54-79.47%), respectively.

CONCLUSION

The present study reveals that CSRS has fair accuracy in differentiating the source of syncope and has no superiority over a clinical examination. Therefore, we do not recommend relying on the CSRS to differentiate between cardiac and non-cardiac syncope alone.

Syncope and the aging patient: Navigating the challenges

Syncope in the elderly patient is a common presentation and the most common causes are usually non-cardiac. Older adults however are more challenging dilemmas as their presentation is complicated by co-morbidities, mainly cardiovascular and neurodegenerative disorders. Frailty and cognitive impairment add to the ambiguity of the presentation, and polypharmacy is often a major modifiable contributing factor. Vasovagal syncope is a common presentation throughout life even as we age. It has a favorable prognosis and conservative management usually suffices. Vasovagal syncope in this population may be misdiagnosed as accidental falls and is frequently associated with injury, as is carotid sinus syndrome. The initial approach to these patients entails a detailed history and physical examination including a comprehensive medication history, orthostatic vital signs, and a 12-lead electrocardiogram. Further cardiac and neuroimaging rarely helps, unless directed by specific clinical findings. Head-up tilt testing and carotid sinus massage retain their diagnostic accuracy and safety in the elderly, and implantable loop recorders provide important information in many elderly patients with unexplained falls and syncope. The starting point in management of this population with non-cardiac syncope is attempting to withdraw unnecessary vasoactive and psychotropic medications. Non-pharmacologic and pharmacologic therapy for syncope in the elderly has limited efficacy and safety concerns. In selected patients, pacemaker therapy might offer symptomatic relief despite lack of efficacy when vasodepression is prominent. An approach focused on primary care with targeted specialist referral seems a safe and effective strategy.

Developing and Demonstrating the Viability and Availability of the Multilevel Implementation Strategy for Syncope Optimal Care Through Engagement (MISSION) Syncope App: Evidence-Based Clinical Decision Support Tool

BACKGROUND

Syncope evaluation and management is associated with testing overuse and unnecessary hospitalizations. The 2017 American College of Cardiology/American Heart Association (ACC/AHA) Syncope Guideline aims to standardize clinical practice and reduce unnecessary services. The use of clinical decision support (CDS) tools offers the potential to successfully implement evidence-based clinical guidelines. However, CDS tools that provide an evidence-based differential diagnosis (DDx) of syncope at the point of care are currently lacking.

OBJECTIVE

With input from diverse health systems, we developed and demonstrated the viability of a mobile app, the Multilevel Implementation Strategy for Syncope optImal care thrOugh eNgagement (MISSION) Syncope, as a CDS tool for syncope diagnosis and prognosis.

METHODS

Development of the app had three main goals: (1) reliable generation of an accurate DDx, (2) incorporation of an evidence-based clinical risk tool for prognosis, and (3) user-based design and technical development. To generate a DDx that incorporated assessment recommendations, we reviewed guidelines and the literature to determine clinical assessment questions (variables) and likelihood ratios (LHRs) for each variable in predicting etiology. The creation and validation of the app diagnosis occurred through an iterative clinician review and application to actual clinical cases. The review of available risk score calculators focused on identifying an easily applied and valid evidence-based clinical risk stratification tool. The review and decision-making factors included characteristics of the original study, clinical variables, and validation studies. App design and development relied on user-centered design principles. We used observations of the emergency department workflow, storyboard demonstration, multiple mock review sessions, and beta-testing to optimize functionality and usability.

RESULTS

The MISSION Syncope app is consistent with guideline recommendations on evidence-based practice (EBP), and its user interface (UI) reflects steps in a real-world patient evaluation: assessment, DDx, risk stratification, and recommendations. The app provides flexible clinical decision making, while emphasizing a care continuum; it generates recommendations for diagnosis and prognosis based on user input. The DDx in the app is deemed a pragmatic model that more closely aligns with real-world clinical practice and was validated using actual clinical cases. The beta-testing of the app demonstrated well-accepted functionality and usability of this syncope CDS tool.

CONCLUSIONS

The MISSION Syncope app development integrated the current literature and clinical expertise to provide an evidence-based DDx, a prognosis using a validated scoring system, and recommendations based on clinical guidelines. This app demonstrates the importance of using research literature in the development of a CDS tool and applying clinical experience to fill the gaps in available research. It is essential for a successful app to be deliberate in pursuing a practical clinical model instead of striving for a perfect mathematical model, given available published evidence. This hybrid methodology can be applied to similar CDS tool development.

Syncope Time Frames for Adverse Events after Emergency Department Presentation: An Individual Patient Data Meta-Analysis

Background and Objectives: Knowledge of the incidence and time frames of the adverse events of patients presenting syncope at the ED is essential for developing effective management strategies. The aim of the present study was to perform a meta-analysis of the incidence and time frames of adverse events of syncope patients. Materials and Methods: We combined individual patients’ data from prospective observational studies including adult patients who presented syncope at the ED. We assessed the pooled rate of adverse events at 24 h, 72 h, 7–10 days, 1 month and 1 year after ED evaluation. Results: We included nine studies that enrolled 12,269 patients. The mean age varied between 53 and 73 years, with 42% to 57% females. The pooled rate of adverse events was 5.1% (95% CI 3.4% to 7.7%) at 24 h, 7.0% (95% CI 4.9% to 9.9%) at 72 h, 8.4% (95% CI 6.2% to 11.3%) at 7–10 days, 10.3% (95% CI 7.8% to 13.3%) at 1 month and 21.3% (95% CI 15.8% to 28.0%) at 1 year. The pooled death rate was 0.2% (95% CI 0.1% to 0.5%) at 24 h, 0.3% (95% CI 0.1% to 0.7%) at 72 h, 0.5% (95% CI 0.3% to 0.9%) at 7–10 days, 1% (95% CI 0.6% to 1.7%) at 1 month and 5.9% (95% CI 4.5% to 7.7%) at 1 year. The most common adverse event was arrhythmia, for which its rate was 3.1% (95% CI 2.0% to 4.9%) at 24 h, 4.8% (95% CI 3.5% to 6.7%) at 72 h, 5.8% (95% CI 4.2% to 7.9%) at 7–10 days, 6.9% (95% CI 5.3% to 9.1%) at 1 month and 9.9% (95% CI 5.5% to 17) at 1 year. Ventricular arrhythmia was rare. Conclusions: The risk of death or life-threatening adverse event is rare in patients presenting syncope at the ED. The most common adverse events are brady and supraventricular arrhythmias, which occur during the first 3 days. Prolonged ECG monitoring in the ED in a short stay unit with ECG monitoring facilities may, therefore, be beneficial.

Personalised risk prediction following emergency department assessment for syncope

BACKGROUND

Published risk tools do not provide possible management options for syncope in the emergency department (ED). Using the 30-day observed risk estimates based on the Canadian Syncope Risk Score (CSRS), we developed personalised risk prediction to guide management decisions.

METHODS

We pooled previously reported data from two large cohort studies, the CSRS derivation and validation cohorts, that prospectively enrolled adults (≥16 years) with syncope at 11 Canadian EDs between 2010 and 2018. Using this larger cohort, we calculated the CSRS calibration and discrimination, and determined with greater precision than in previous studies the 30-day risk of adjudicated serious outcomes not identified during the index ED evaluation depending on the CSRS and the risk category. Based on these findings, we developed an on-line calculator and pictorial decision aids.

RESULTS

8233 patients were included of whom 295 (3.6%, 95% CI 3.2% to 4.0%) experienced 30-day serious outcomes. The calibration slope was 1.0, and the area under the curve was 0.88 (95% CI 0.87 to 0.91). The observed risk increased from 0.3% (95% CI 0.2% to 0.5%) in the very-low-risk group (CSRS -3 to -2) to 42.7% (95% CI 35.0% to 50.7%), in the very-high-risk (CSRS≥+6) group (Cochrane-Armitage trend test p<0.001). Among the very-low and low-risk patients (score -3 to 0), ≤1.0% had any serious outcome, there was one death due to sepsis and none suffered a ventricular arrhythmia. Among the medium-risk patients (score +1 to+3), 7.8% had serious outcomes, with <1% death, and a serious outcome was present in >20% of high/very-high-risk patients (score +4 to+11) including 4%-6% deaths. The online calculator and the pictorial aids can be found at: https://teamvenk.com/csrs CONCLUSIONS: 30-day observed risk estimates from a large cohort of patients can be obtained for management decision-making. Our work suggests very-low-risk and low-risk patients may be discharged, discussion with patients regarding investigations and disposition are needed for medium-risk patients, and high-risk patients should be hospitalised. The online calculator, accompanied by pictorial decision aids for the CSRS, may assist in discussion with patients.

Validated scoring system identifies low-risk syncope patients

This study validated the Canadian Syncope Risk Score for predicting 30-day serious outcomes in patients presenting to the ED within 24 hours of syncope.

Can I Send This Syncope Patient Home From the Emergency Department?

BACKGROUND

Syncope is a common presentation to the emergency department (ED). A significant minority of these patients have potentially life-threatening pathology. Reliably identifying that patients require hospital admission for further workup and intervention is imperative.

CLINICAL QUESTION

In patients who present with syncope, is there a reliable decision tool that clinicians can use to predict the risk of adverse outcome and determine who may be appropriate for discharge?

EVIDENCE REVIEW

Four articles were reviewed. The first retrospective study found no difference in mortality or adverse events in patients admitted for further evaluation rather than discharged home with primary care follow-up. The next two articles examined the derivation and validation of the Canadian Syncope Risk Score (CSRS). After validation with an admission threshold score of -1, the sensitivity and specificity of the CSRS was 97.8% (95% confidence interval [CI] 93.8-99.6%) and 44.3% (95% CI 42.7-45.9%), respectively. The last article looked at the derivation of the FAINT score, a recently developed score to risk stratify syncope patients. A FAINT score of ≥ 1 (any score 1 or higher should be admitted) had a sensitivity of 96.7% (95% CI 92.9-98.8%) and specificity 22.2% (95% CI 20.7-23.8%).

CONCLUSIONS

Syncope remains a difficult chief symptom to disposition from the ED. The CSRS is modestly effective at establishing a low probability of actionable disease or need for intervention. However, CSRS might not reduce unnecessary hospitalizations. The FAINT score has yet to undergo validation; however, the initial derivation study offers less diagnostic accuracy compared with the CSRS.

Intra-cluster correlations from the CLustered OUtcome Dataset bank to inform the design of longitudinal cluster trials

BACKGROUND

Sample size calculations for longitudinal cluster randomised trials, such as crossover and stepped-wedge trials, require estimates of the assumed correlation structure. This includes both within-period intra-cluster correlations, which importantly differ from conventional intra-cluster correlations by their dependence on period, and also cluster autocorrelation coefficients to model correlation decay. There are limited resources to inform these estimates. In this article, we provide a repository of correlation estimates from a bank of real-world clustered datasets. These are provided under several assumed correlation structures, namely exchangeable, block-exchangeable and discrete-time decay correlation structures.

METHODS

Longitudinal studies with clustered outcomes were collected to form the CLustered OUtcome Dataset bank. Forty-four available continuous outcomes from 29 datasets were obtained and analysed using each correlation structure. Patterns of within-period intra-cluster correlation coefficient and cluster autocorrelation coefficients were explored by study characteristics.

RESULTS

The median within-period intra-cluster correlation coefficient for the discrete-time decay model was 0.05 (interquartile range: 0.02-0.09) with a median cluster autocorrelation of 0.73 (interquartile range: 0.19-0.91). The within-period intra-cluster correlation coefficients were similar for the exchangeable, block-exchangeable and discrete-time decay correlation structures. Within-period intra-cluster correlation coefficients and cluster autocorrelations were found to vary with the number of participants per cluster-period, the period-length, type of cluster (primary care, secondary care, community or school) and country income status (high-income country or low- and middle-income country). The within-period intra-cluster correlation coefficients tended to decrease with increasing period-length and slightly decrease with increasing cluster-period sizes, while the cluster autocorrelations tended to move closer to 1 with increasing cluster-period size. Using the CLustered OUtcome Dataset bank, an RShiny app has been developed for determining plausible values of correlation coefficients for use in sample size calculations.

DISCUSSION

This study provides a repository of intra-cluster correlations and cluster autocorrelations for longitudinal cluster trials. This can help inform sample size calculations for future longitudinal cluster randomised trials.

External validation of the Canadian Syncope Risk Score for patients presenting with undifferentiated syncope to the emergency department

OBJECTIVE

To validate the accuracy and safety of the Canadian Syncope Risk Score (CSRS) for patients presenting with syncope.

METHODS

Single centre prospective observational study in Brisbane, Australia. Adults presenting to the ED with syncope within the last 24 h were recruited after applying exclusion criteria. Study was conducted over 1 year, from March 2018 to March 2019. Thirty-day serious adverse events (SAE) were reported based on the original derivation study and standardised outcome reporting for syncope. Individual patient CSRS was calculated and correlated with 30-day SAE and disposition status from ED.

RESULTS

Two hundred and eighty-three patients were recruited to the study. Average age was 55.6 years (SD 22.7 years), 37.1% being male with a 39.9% admission rate. Thirty-day SAE occurred in seven patients (2.5%) and no recorded deaths. The CSRS performed with a sensitivity of 71.4% (95% confidence interval [CI] 30.3-94.9%), specificity 72.8% (95% CI 67.1-77.9%) for a threshold score of 1 or higher.

CONCLUSION

Syncope patients in our study were predominantly very low to low risk (72%). The prevalence of 30-day SAE was low, majority occurring following hospital discharge. Sensitivity estimates for CSRS was lower than the derivation study but lacked robustness with wide CIs because of a small sample size and number of events observed. However, the CSRS did not miss any clinically relevant outcomes in low risk patients making it potentially useful in aiding their disposition. Larger validation studies in Australia are encouraged to further test the diagnostic accuracy of the CSRS.

Multicentre external validation of the Canadian Syncope Risk Score to predict adverse events and comparison with clinical judgement

BACKGROUND

The Canadian Syncope Risk Score (CSRS) has been proposed for syncope risk stratification in the emergency department (ED). The aim of this study is to perform an external multicenter validation of the CSRS and to compare it with clinical judgement.

METHODS

Using patients previously included in the SyMoNE database, we enrolled subjects older than 18 years who presented reporting syncope at the ED. For each patient, we estimated the CSRS and recorded the physician judgement on the patients' risk of adverse events. We performed a 30-day follow-up.

RESULTS

From 1 September 2015 to 28 February 2017, we enrolled 345 patients; the median age was 71 years (IQR 51-81), 174 (50%) were men and 29% were hospitalised. Serious adverse events occurred in 43 (12%) of the patients within 30 days. The area under the curve of the CSRS and clinical judgement was 0.75 (95% CI 0.68 to 0.81) and 0.68 (95% CI 0.61 to 0.74), respectively. The risk of adverse events of patients at low risk according to the CSRS and clinical judgement was 6.7% and 2%, with a sensitivity of 70% (95% CI 54% to 83%) and 95% (95% CI 84% to 99%), respectively.

CONCLUSION

This study represents the first validation analysis of CSRS outside Canada. The overall predictive accuracy of the CSRS is similar to the clinical judgement. However, patients at low risk according to clinical judgement had a lower incidence of adverse events as compared with patients at low risk according to the CSRS. Further studies showing that the adoption of the CSRS improve patients' outcomes is warranted before its widespread implementation.

A Rational Evaluation of the Syncope Patient: Optimizing the Emergency Department Visit

Syncope accounts for up to 2% of emergency department visits and results in the hospitalization of 12–86% of patients. There is often a low diagnostic yield, with up to 50% of hospitalized patients being discharged with no clear diagnosis. We will outline a structured approach to the syncope patient in the emergency department, highlighting the evidence supporting the role of clinical judgement and the initial electrocardiogram (ECG) in making the preliminary diagnosis and in safely identifying the patients at low risk of short- and long-term adverse events or admitting the patient if likely to benefit from urgent intervention. Clinical decision tools and additional testing may aid in further stratifying patients and may guide disposition. While hospital admission does not seem to offer additional mortality benefit, the efficient utilization of outpatient testing may provide similar diagnostic yield, preventing unnecessary hospitalizations.

Multivariable risk scores for predicting short-term outcomes for emergency department patients with unexplained syncope: A systematic review

OBJECTIVES

Emergency department (ED) patients with unexplained syncope are at risk of experiencing an adverse event within 30 days. Our objective was to systematically review the accuracy of multivariate risk stratification scores for identifying adult syncope patients at high and low risk of an adverse event over the next 30 days.

METHODS

We conducted a systematic review of electronic databases (MEDLINE, Cochrane, Embase, and CINAHL) from database creation until May 2020. We sought studies evaluating prediction scores of adults presenting to an ED with syncope. We included studies that followed patients for up to 30 days to identify adverse events such as death, myocardial infarction, stroke, or cardiac surgery. We only included studies with a blinded comparison between baseline clinical features and adverse events. We calculated likelihood ratios and confidence intervals (CIs).

RESULTS

We screened 13,788 abstracts. We included 17 studies evaluating nine risk stratification scores on 24,234 patient visits, where 7.5% (95% CI = 5.3% to 10%) experienced an adverse event. A Canadian Syncope Risk Score (CSRS) of 4 or more was associated with a high likelihood of an adverse event (LR_score≥4  = 11, 95% CI = 8.9 to 14). A CSRS of 0 or less (LR_score≤0  = 0.10, 95% CI = 0.07 to 0.20) was associated with a low likelihood of an adverse event. Other risk scores were not validated on an independent sample, had low positive likelihood ratios for identifying patients at high risk, or had high negative likelihood ratios for identifying patients at low risk.

CONCLUSION

Many risk stratification scores are not validated or not sufficiently accurate for clinical use. The CSRS is an accurate validated prediction score for ED patients with unexplained syncope. Its impact on clinical decision making, admission rates, cost, or outcomes of care is not known.

Machine Learning and Syncope Management in the ED: The Future Is Coming

In recent years, machine learning (ML) has been promisingly applied in many fields of clinical medicine, both for diagnosis and prognosis prediction. Aims of this narrative review were to summarize the basic concepts of ML applied to clinical medicine and explore its main applications in the emergency department (ED) setting, with a particular focus on syncope management. Through an extensive literature search in PubMed and Embase, we found increasing evidence suggesting that the use of ML algorithms can improve ED triage, diagnosis, and risk stratification of many diseases. However, the lacks of external validation and reliable diagnostic standards currently limit their implementation in clinical practice. Syncope represents a challenging problem for the emergency physician both because its diagnosis is not supported by specific tests and the available prognostic tools proved to be inefficient. ML algorithms have the potential to overcome these limitations and, in the future, they could support the clinician in managing syncope patients more efficiently. However, at present only few studies have addressed this issue, albeit with encouraging results.

A qualitative study to identify factors that influence patients' decisions to call Emergency Medical Services for syncope

BACKGROUND

Protocols that support paramedics to assess, treat and refer low-risk syncope (fainting) may allow for ED transport of only high-risk patients. The development and uptake of such protocols is limited by a dearth of information about factors patients consider when deciding to seek EMS care following syncope.

OBJECTIVE

We explored decision-making processes of individuals with syncope regarding whether (or not) to call EMS after fainting as a starting point in the development of prehospital risk-stratification protocols for syncope.

METHODS

Twenty-five Canadian adults (aged 18-65 years) with a history of ≥ 1 syncopal episode were recruited. Individual semi-structured interviews were conducted, recorded, and transcribed. Straussian grounded theory methods were used to identify common themes and a core (overarching) category.

RESULTS

Four themes were identified: (a) previous experiences with the healthcare system (e.g., feeling dismissed), (b) individual patient factors (e.g., age, medical history), (c) attitudes and beliefs (e.g., burdening the health care system, syncope is "not serious"), and (d) contextual factors (e.g., influence of important others, symptom severity). Perceived judgement, including judgement from EMS and negative self-evaluations, was identified as the core category that influenced patients' decisions to seek care.

CONCLUSION

We theorize that, while patients consider many factors in deciding to contact EMS for syncope, previous experiences of feeling judged and unfavorable beliefs about syncope may interfere with patients' receptiveness to traditional EMS protocols for syncope. The findings highlight potential patient needs that program developers may wish to consider in the development of prehospital protocols to improve care and satisfaction among patients with syncope.

Adverse Events Among Emergency Department Patients With Cardiovascular Conditions: A Multicenter Study

STUDY OBJECTIVE

We aim to determine incidence and type of adverse events (adverse outcomes related to emergency care) among emergency department (ED) patients discharged with recent-onset atrial fibrillation, acute heart failure, and syncope.

METHODS

This 5-year prospective cohort study included high-acuity adult patients discharged with the 3 sentinel diagnoses from 6 tertiary care Canadian EDs. We screened all ED visits for eligibility and performed telephone interviews 14 days postdischarge to identify flagged outcomes: death, hospital admission, return ED visit, health care provider visit, and new or worsening symptoms. We created case summaries describing index ED visit and flagged outcomes, and trained emergency physicians reviewed case summaries to identify adverse events. We reported adverse event incidence and rates with 95% confidence intervals and contributing factor themes.

RESULTS

Among 4,741 subjects (mean age 70.2 years; 51.2% men), we observed 170 adverse events (3.6 per 100 patients; 95% confidence interval 3.1 to 4.2). Patients discharged with acute heart failure were most likely to experience adverse events (5.3%), followed by those with atrial fibrillation (2.0%) and syncope (0.8%). We noted variation in absolute adverse event rates across sites from 0.7 to 6.0 per 100 patients. The most common adverse event types were management issues, diagnostic issues, and unsafe disposition decisions. Frequent contributing factor themes included failure to recognize underlying causes and inappropriate management of dual diagnoses.

CONCLUSION

Among adverse events after ED discharge for patients with these 3 sentinel cardiovascular diagnoses, we identified quality improvement opportunities such as strengthening dual diagnosis detection and evidence-based clinical practice guideline adherence.

Development of an electrocardiogram-based risk calculator for a cardiac cause of syncope

OBJECTIVE

To develop an ECG-based tool for rapid risk assessment of a cardiac cause of syncope in patients ≥40 years.

METHODS

In a prospective international multicentre study, 2007 patients ≥40 years presenting with syncope were recruited in the emergency department (ED) of participating centres ranging from large university hospitals to smaller rural hospitals in eight countries from May 2010 to July 2017. 12-Lead ECG recordings were obtained at ED presentation following the syncopal event. The primary diagnostic outcome, a cardiac cause of syncope, was centrally adjudicated by two independent cardiologists using all available clinical information including 12-month follow-up. ECG predictors for a cardiac cause of syncope were identified using penalised backward selection and a continuous-scale likelihood was calculated based on regression analysis coefficients. Findings were validated in an independent US multicentre cohort including 2269 patients.

RESULTS

In the derivation cohort, a cardiac cause of syncope was adjudicated in 267 patients (16%). Seven ECG criteria were identified as predictors for this outcome: heart rate and QTc-interval (continuous predictors), rhythm, atrioventricular block, ST-segment depression, bundle branch block and ventricular extrasystole/non-sustained ventricular tachycardia (categorical predictors). Diagnostic accuracy of these combined predictors for a cardiac cause of syncope was high (area under the curve 0.80, 95% CI 0.77 to 0.83). Overall, 138 patients (8%) were rapidly triaged towards rule-out and 181 patients (11%) towards rule-in of a cardiac cause of syncope. External validation showed similar performance.

CONCLUSION

In patients ≥40 years with a syncopal event, a combination of seven ECG criteria enabled rapid assessment of the likelihood that syncope was due to a cardiac cause.

TRIAL REGISTRATION NUMBER

NCT01548352 (BASEL IX), NCT01802398 (SRS study).