Predicting the cause of syncope from clinical history in patients undergoing prolonged monitoring

Predictors of pacemaker requirement in patients with implantable loop recorder and unexplained syncope: A systematic review and meta-analysis

Identifying the underlying cause of unexplained syncope is crucial for appropriate management of recurrent syncopal episodes. Implantable loop recorders (ILRs) have emerged as valuable diagnostic tools for monitoring patients with unexplained syncope. However, the predictors of pacemaker requirement in patients with ILR and unexplained syncope remain unclear. In this study, we shed light on these prognostic factors. PubMed/MEDLINE, EMBASE, Web of Science, and Cochrane CENTRAL were systematically searched until May 04, 2023. Studies that evaluated the predictors of pacemaker requirement in patients with implantable loop recorder and unexplained syncope were included. The "Quality In Prognosis Studies" appraisal tool was used for quality assessment. The pooled odds ratio (OR) with 95% confidence intervals (CIs) was calculated. The publication bias was evaluated using Egger's and Begg's tests. Ten studies (n = 4200) were included. Right bundle branch block (OR: 3.264; 95% CI: 1.907-5.588, p < .0001) and bifascicular block (OR: 2.969; 95% CI: 1.859-4.742, p < .0001) were the strongest predictors for pacemaker implantation. Pacemaker requirement was more than two times in patients with atrial fibrillation, sinus bradycardia and first degree AV block. Valvular heart disease, diabetes mellitus, and hypertension were also significantly more in patients with pacemaker implantation. Age (standardized mean difference [SMD]: 0.560; 95% CI: 0.410/0.710, p < .0001) and PR interval (SMD: 0.351; 95% CI: 0.150/0.553, p = .001) were significantly higher in patients with pacemaker requirement. Heart conduction disorders, atrial arrhythmias and underlying medical conditions are main predictors of pacemaker device implantation following loop recorder installation in unexplained syncopal patients.

An old diagnostic tool for new indications: inpatient Holter ECG for conditions other than syncope or stroke

Holter electrocardiography (ECG) assists in the diagnosis of arrhythmias. Its use in the inpatient setting has been described solely for the evaluation of stroke and syncope. Our aim was to assess its diagnostic value for other conditions in the internal medicine department. We included all hospitalized patients between 2018 and 2021 in a tertiary referral center. The primary outcome was a diagnostic Holter recording a new arrhythmia that led to a change in treatment. Overall, 289 patients completed a 24-h inpatient Holter ECG for conditions other than syncope or stroke, with 39 (13%) diagnostic findings. The highest diagnostic value was found in patients admitted for pre-syncope (19%), palpitations (18%), and unexplained heart failure exacerbation/dyspnea (17%). A low diagnostic yield was found for the evaluation of chest pain (5%). Heart failure with preserved ejection fraction (adjusted OR 2.3, 95% CI 1.1-5.4, p = 0.04), and baseline ECG with either a bundle branch block (AOR 4.2, 95% CI 1.9-9.2, p < 0.01) or atrioventricular block (first or second degree, AOR 5, 95% CI 2.04-12.3, p < 0.01) were among the independent predictors for a diagnostic test. Inpatient Holter ECG monitoring may have value as a diagnostic tool for selected patients with conditions other than syncope or stroke.

Holter ECG for Syncope Evaluation in the Internal Medicine Department-Choosing the Right Patients

Physicians use Holter electrocardiography (ECG) monitoring to evaluate some patients with syncope in the internal medicine department. We questioned whether Holter ECG should be used in the presented setting. Included were all consecutive patients admitted with syncope to one of our nine internal medicine departments who had completed a 24 h Holter ECG between 2018 and 2021. A diagnostic Holter was defined as one which altered the patient’s treatment and met ESC/ACC/AHA diagnostic criteria. A total of 478 Holter tests were performed for syncope evaluation during admission to an internal medicine department in the study period. Of them, 25 patients (5.2%) had a diagnostic Holter finding. Sinus node dysfunction was the most frequent diagnostic recording (13 patients, 52%). In multivariant analysis, predictors for diagnostic Holter were older age (OR 1.35, 95% CI 1.08−1.68), heart failure with preserved ejection fraction (OR 4.1, 95% CI 1.43−11.72), and shorter duration to Holter initiation (OR 0.73, 95% CI 0.56−0.96). There was a positive correlation between time from admission to Holter and hospital stay, r(479) = 0.342, p < 0.001. Our results suggest that completing a 24 h Holter monitoring during admission to the internal medicine department should be restricted to patients with a high pre-test probability to avoid overuse and possible harm.

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.

When Is Syncope Arrhythmic?

Cardiac arrhythmia is a common cause of syncope. The prompt identification of arrhythmic syncope has diagnostic and prognostic implications. In this article, an approach to identifying and managing arrhythmic syncope is discussed, including key findings from the history, physical examination, electrocardiogram, role of risk stratification, use of supplemental investigations, and treatment.

Predictors of positive electrophysiological study in patients with syncope and bundle branch block: PR interval and type of conduction disturbance

BACKGROUND

Electrophysiological study (EPS) is indicated in patients with syncope and bundle branch block (BBB). Data about predictors of positive EPS in these patients is scarce.

OBJECTIVE

To assess clinical and electrocardiographic (ECG) predictors of positive EPS in patients with syncope and BBB.

METHODS

Observational single-center study that included all consecutive patients with syncope and BBB that underwent EPS from January 2011 to June 2017. Results of EPS were considered positive according to current ESC syncope guidelines.

RESULTS

During study period, 271 patients were included (64.9% male, age: 73.9 ± 12.2 years, number of syncopal episodes: 2.4 ± 2.5, LVEF: 56.1 ± 9.9%). Type of BBB: RBBB + LAFB/LPFB in 39.8%, isolated LBBB in 38.7% and isolated RBBB in 18.5% of the patients. Duration of QRS and PR interval were 141.9 ± 16.7 and 182.8 ± 52.2 milliseconds. EPS was positive in 41.7% of the patients. In multivariate analysis, conduction disturbance pattern and long PR interval (OR 8.6; 2.9-25; P < 0.0001) were predictors of positive EPS. Conduction disturbance patterns related with positive EPS were: BBB different than isolated RBBB (OR 15.2; 2.2-23.4; P = 0.005), LBBB or RBBB+long PR + left fascicular block (OR 4.5; 1.06-20.01; P < 0.042), and RBBB+left fascicular block compared with LBBB (OR 4.8; 1.2-16.7; P = 0.025). Clinical factors and syncope characteristics were not related with EPS result.

CONCLUSIONS

Diagnostic yield of EPS in patients with syncope and BBB is moderate (41%). Type of conduction disturbance pattern and PR interval are associated with the electrophysiological (EP) test result. Patients with LBBB or bifascicular block have the highest rate of positive EP test. Long PR interval increases the proportion of positive EPS in all conduction disturbance patterns.

[Syncope and fitness to drive]

Although medical students are rarely instructed in traffic medicine in Germany, they are obliged to inform their patients about their fitness to drive after having become a medical doctor. This article gives an overview on the fitness to drive for patients with syncope by referring to the driving license regulation and the current guidelines released by the department of traffic. The driving license regulation distinguishes between group 1 and group 2 drivers. Group 1 drivers drive vehicles with a total weight less than 3.5 t, whereas group 2 drivers drive vehicles with a total weight above 3.5 t or provide commercial passenger transport. Since patients with syncope may suffer from different serious illnesses, the first approach is to clarify the cause of syncope. If no treatable cause of syncope (e. g., pacemaker, aortic valve replacement) is found, drivers of group 1 are not fit to drive for 6 months after a second unexplained syncope, whereas in this situation, drivers of group 2 are not fit to drive permanently. If, however, syncopes occur in conditions which cannot be expected to occur while driving (e. g. venipuncture, defecation, micturition) fitness to drive will persist. Syncope due to ventricular tachycardia in ischemic heart disease and reduced left ventricular ejection fraction are in general treated with an implantable cardioverter-defibrillator (ICD). Group 2 drivers with an ICD are normally unfit to drive. Group 1 drivers with an ICD are fit to drive when no syncope or adequate shock occurred within the last three months.

Implantable loop recorders in patients with unexplained syncope: Clinical predictors of pacemaker implantation

BACKGROUND

Implantable loop recorders (ILR) are a valuable tool for the investigation of unexplainedsyncopal episodes. The aim of this retrospective single center study was to identify predictive factors for pacemaker implantation in patients with unexplained syncope who underwent ILR insertion.

METHODS

One hundred six patients were retrospectively analyzed (mean age 59.1 years; 47.2% male) with unexplained syncope and negative conventional testing who underwent ILR implantation. The pri- mary study endpoint was detection of symptomatic or asymptomatic bradycardia requiring pacemaker implantation.

RESULTS

The average follow-up period after ILR implantation was 20 ± 15 months. Pacemaker im- plantation according to current guidelines was necessary in 22 (20.8%) patients, mean duration until index bradycardia was 81 ± 88 (2-350) days. Ten (45.5%) patients received a pacemaker due to sinus arrest, 7 (31.8%) patients due to third-degree atrioventricular block, 2 (9.1%) patients due to second- degree atrioventricular block and 1 (4.5%) patient due to atrial fibrillation with a slow ventricular rate. Three factors remained significant in multivariate analysis: obesity, which defined by a body mass index above 30 kg/m2 (OR: 7.39, p = 0.014), a right bundle branch block (OR: 9.40, p = 0.023) and chronic renal failure as defined by a glomerular filtration rate of less than 60 mL/min (OR: 6.42, p = 0.035).

CONCLUSIONS

Bradycardia is a frequent finding in patients undergoing ILR implantation due to un- explained syncope. Obesity, right bundle branch block and chronic renal failure are independent clinical predictors of pacemaker implantation.

Clinical Mimics: An Emergency Medicine-Focused Review of Syncope Mimics

BACKGROUND

Syncope is an event that causes a transient loss of consciousness (LOC) secondary to global cerebral hypoperfusion. The transient nature of the event can make diagnosis in the emergency department (ED) difficult, as symptoms have often resolved by time of initial presentation. The symptoms and presentation of syncope are similar to many other conditions, which can lead to difficulty in establishing a diagnosis in the ED.

OBJECTIVE

This review evaluates patients presenting with a history concerning for possible syncope, mimics of syncope, and approach to managing syncope mimics.

DISCUSSION

Syncope is caused by transient LOC secondary to global cerebral hypoperfusion. Many conditions can present similarly to syncope, making diagnosis in the ED difficult. Some of the most emergent conditions include seizures, stroke, metabolic disorders, and head trauma. Other nonemergent conditions include cataplexy, pseudosyncope, or deconditioning. Many laboratory studies and imaging can be nondiagnostic during ED evaluation. For patients presenting with apparent syncope, immediate treatment should focus on identifying and treating life-threatening conditions. History and physical examination can help guide further diagnostic evaluation and management.

CONCLUSIONS

Patients with apparent syncope should be evaluated for potential immediate life-threatening conditions. A thorough history and physical examination can aid in distinguishing syncope from common mimics and help identify and subsequently treat life-threatening conditions.

Syncope: diagnosis and management

Syncope is defined as transient loss of consciousness due to global cerebral hypoperfusion. It is characterized by having a relatively rapid onset, brief duration with spontaneous and full recovery. The major challenge in the evaluation of patients with syncope is that most patients are asymptomatic at the time of their presentation. A thorough history and physical examination including orthostatic assessment are crucial for making the diagnosis. After initial evaluation, short-term risk assessment should be performed to determine the need for admission. If the short-term risk is high, inpatient evaluation is needed. If the short-term risk is low, outpatient evaluation is recommended. In patients with suspected cardiac syncope, monitoring is indicated until a diagnosis is made. In patients with suspected reflex syncope or orthostatic hypotension, outpatient evaluation with tilt-table testing is appropriate. Syncope units have been shown to improve the rate of diagnosis while reducing cost and thus are highly recommended.

Unexplained syncope: implications of age and gender on patient characteristics and evaluation, the diagnostic yield of an implantable loop recorder, and the subsequent treatment

BACKGROUND

Syncope is a common clinical problem with a variety of underlying mechanisms, some of which occur more frequently in 1 of the sexes or at a certain age.

HYPOTHESIS

There may be clinically significant age- and gender-related differences in patients with unexplained syncope.

METHODS

Five hundred seventy patients (54% women) with unexplained syncope received an implantable loop recorder (ILR) and were followed until diagnosis or for at least 1 year.

RESULTS

Women were older and more prone to severe trauma during syncope (40.8% vs 29.9%, P = 0.007), and hospitalization was more common at ≥65 years (P = 0.003) without gender difference. Muscle spasms or grand mal seizures were more common in men and at <65 years old. Carotid sinus pressure, exercise testing, coronary angiography and magnetic resonance imaging/computed tomography scans were more commonly performed in men, whereas no test was more common in women. Tilt testing, exercise test, electroencephalography, and neurological or psychiatric evaluation were more common at ≥65 years. There were no age- or gender-related differences in the diagnostic yield of the ILR, whereas patients ≥65 years old more often received specific treatment based on ILR data.

CONCLUSIONS

Gender and/or age had relevance for the clinical evaluation, rate of recurrence, and subsequent specific treatment but not for the diagnostic yield of the ILR.

Identifying cardiac syncope based on clinical history: a literature-based model tested in four independent datasets

BACKGROUND

We aimed to develop and test a literature-based model for symptoms that associate with cardiac causes of syncope.

METHODS AND RESULTS

Seven studies (the derivation sample) reporting ≥2 predictors of cardiac syncope were identified (4 Italian, 1 Swiss, 1 Canadian, and 1 from the United States). From these, 10 criteria were identified as diagnostic predictors. The conditional probability of each predictor was calculated by summation of the reported frequencies. A model of conditional probabilities and a priori probabilities of cardiac syncope was constructed. The model was tested in four datasets of patients with syncope (the test sample) from Calgary (n=670; 21% had cardiac syncope), Amsterdam (n=503; 9%), Milan (n=689; 5%) and Rochester (3877; 11%). In the derivation sample ten variables were significantly associated with cardiac syncope: age, gender, structural heart disease, low number of spells, brief or absent prodrome, supine syncope, effort syncope, and absence of nausea, diaphoresis and blurred vision. Fitting the test datasets to the full model gave C-statistics of 0.87 (Calgary), 0.84 (Amsterdam), 0.72 (Milan) and 0.71 (Rochester). Model sensitivity and specificity were 92% and 68% for Calgary, 86% and 67% for Amsterdam, 76% and 59% for Milan, and 73% and 52% for Rochester. A model with 5 variables (age, gender, structural heart disease, low number of spells, and lack of prodromal symptoms) was as accurate as the total set.

CONCLUSION

A simple literature-based Bayesian model of historical criteria can distinguish patients with cardiac syncope from other patients with syncope with moderate accuracy.

Syncope diagnostic scores

The diagnosis of syncope poses unique challenges. Syncope has multiple etiologies, with most carrying benign prognoses, and a few less common causes carrying a risk of serious morbidity or death. The history at first glance carries few clues. Faced with this many patients are heavily investigated with tests known to be both useless and expensive. For these reasons considerable emphasis has been placed on developing evidence-based and quantitative histories that might distinguish among the main causes of syncope. Quantitative histories were first developed in populations of several hundred patients with definite diagnoses of various losses of consciousness. Their derivation and use mirror those of experienced clinicians. The first score - the Calgary Syncope Seizures Score - discriminates between epileptic convulsions and syncope with a sensitivity and specificity of about 94%. The second score, the Calgary Syncope Score for normal hearts, discriminates between vasovagal syncope and other causes of syncope with a sensitivity and specificity of about 90%. The third score, the Calgary Syncope Score for Structural Heart Disease, diagnoses ventricular tachycardia with 98% sensitivity and 71% specificity. It also accurately predicts serious arrhythmic outcomes and all cause death. Gaps in the accuracy of the second score have been identified and are being addressed. These scores are proving useful in the clinic, and as entry criteria for observation studies, genetic studies, and randomized clinical trials. A very simple score predicts vasovagal syncope recurrences, based on the number of faints in the preceding year. Work from several centres indicates that scores will distinguish among competing causes of syncope in select populations, such as those with bifascicular heart block, Brugada syndrome, and Long QT syndrome.

Clinical symptoms associated with asystolic or bradycardic responses on implantable loop recorder monitoring in patients with recurrent syncope

BACKGROUND

Implantable loop recorders (ILR) have been found to be useful in the diagnosis and management of syncope of unclear etiology. The clinical symptoms of abnormalities seen during ILR monitoring have not been adequately studied.

AIM

The aim of this retrospective study was to determine the clinical symptoms which were the best predictors of asystolic or bradycardic responses during ILR monitoring.

METHODS

Patients with either asystole or bradycardia recorded during ILR monitoring were analyzed from our database. The clinical characteristics of these patients were compared to the patients with ILR's who did not have recorded bradycardic episodes. The episodes were characterized as being convulsive or nonconvulsive, brief (<5 minutes) or prolonged (> 5 minutes), and having had a prodrome or no prodrome.

RESULTS

Eleven patients (4 males and 7 females; age 39 +/-11 years) had asystole or bradycardia on ILR monitoring. Eleven patients (2 males and 9 females; age 46+/-23) had no bradycardiac events. Palpitations, convulsive syncope, prolonged episode, and prodrome were present in 37% vs. 74% (P = 0.125), 62% vs. 0% (P = 0.002), 87% vs. 0% (P=0), and 73% vs. 13% (P=0.009) patients, respectively, in the asystole/bradycardia and non-bradycardia groups. In the asystole/bradycardia group eight patients had bradycardia (HR < 20) for > 10 seconds and three patients had asystole >10 seconds.

CONCLUSION

Convulsive syncope, prolonged loss of consciousness during syncopal episode, and absence of prodrome or aura are clinical predictors of asystole or bradycardia on ILR monitoring.