Rates of Cardiac Catheterization Cancelation for ST-Segment Elevation Myocardial Infarction After Activation by Emergency Medical Services or Emergency Physicians

Non-chest pain symptoms and likelihood of coronary occlusion in emergency department patients with ST segment elevation undergoing emergent coronary angiography

OBJECTIVES

Patients presenting with suspected ST segment elevation myocardial infarction frequently have symptoms in addition to chest pain, including dyspnea, nausea or vomiting, diaphoresis, and lightheadedness or syncope. These symptoms are often regarded as supporting the diagnosis of infarction. We sought to determine the prevalence of the non-chest pain symptoms among patients who were confirmed as having a critically diseased coronary vessel as opposed to those with no angiographic culprit lesion.

METHODS

Data from 1393 consecutive patients with ST segment elevation who underwent emergent coronary angiography were analyzed. Records were reviewed in detail for symptoms, ECG findings, prior history, angiographic findings, and in-hospital outcomes.

RESULTS

Dyspnea was present in 50.8% of patients, nausea or vomiting in 36.5%, diaphoresis in 51.2%, and lightheadedness/syncope in 16.8%. On angiography, 1239 (88.9%) patients had a culprit lesion and 154 (11.1%) were found not to have a culprit. Only diaphoresis had a higher prevalence among the patients with, as compared with those without a culprit, with an odds ratio of 2.64 (P < 0.001). The highest occurrence of diaphoresis was among patients with a totally occluded artery, with an intermediate frequency among patients with a subtotal stenosis, and the lowest prevalence among those with no culprit. These findings were consistent regardless of ECG infarct location, affected vessel, patient age, or sex. Among the subset of patients who presented without chest discomfort, none of the symptoms were associated with the presence of a culprit.

CONCLUSION

The presence of diaphoresis, but not dyspnea, nausea, or lightheadedness is associated with an increased likelihood that patients presenting with ST elevation will prove to have a culprit lesion. In patients who present with ST elevation but without chest discomfort, these symptoms should not be regarded as 'chest pain equivalents'. Further objective data among patients with angiographic confirmation of culprit lesion status is warranted.

Analysis of the management of ST-segment elevation myocardial infarction in Spain. Results from the ACI-SEC Infarction Code Registry

INTRODUCTION AND OBJECTIVES

ST-segment elevation myocardial infarction (STEMI) networks should guarantee STEMI care with good clinical results and within the recommended time parameters. There is no contemporary information on the performance of these networks in Spain. The objective of this study was to analyze the clinical characteristics of patients, times to reperfusion, characteristics of the intervention performed, and 30-day mortality.

METHODS

Prospective, observational, multicenter registry of consecutive patients treated in 17 STEMI networks in Spain (83 centers with the Infarction Code), between April 1 and June 30, 2019.

RESULTS

A total of 5401 patients were attended (mean age, 64±13 years; 76.9% male), of which 4366 (80.8%) had confirmed STEMI. Of these, 87.5% were treated with primary angioplasty, 4.4% with fibrinolysis, and 8.1% did not receive reperfusion. In patients treated with primary angioplasty, the time between symptom onset and reperfusion was 193 [135-315] minutes and the time between first medical contact and reperfusion was 107 [80-146] minutes. Overall 30-day mortality due to STEMI was 7.9%, while mortality in patients treated with primary angioplasty was 6.8%.

CONCLUSIONS

Most patients with STEMI were treated with primary angioplasty. In more than half of the patients, the time from first medical contact to reperfusion was <120 minutes. Mortality at 30 days was relatively low.

Late Outcomes of Patients With Prehospital ST-Segment Elevation and Appropriate Cardiac Catheterization Laboratory Nonactivation

Background Patients with suspected ST-segment-elevation myocardial infarction (STEMI) and cardiac catheterization laboratory nonactivation (CCL-NA) or cancellation have reportedly similar crude and higher adjusted risks of death compared with those with CCL activation, though reasons for these poor outcomes are not clear. We determined late clinical outcomes among patients with prehospital ECG STEMI criteria who had CCL-NA compared with those who had CCL activation. Methods and Results We identified consecutive prehospital ECG transmissions between June 2, 2010 to October 6, 2016. Diagnoses according to the Fourth Universal Definition of myocardial infarction (MI), particularly rates of myocardial injury, were adjudicated. The primary outcome was all-cause death. Secondary outcomes included cardiovascular death/MI/stroke and noncardiovascular death. To explore competing risks, cause-specific hazard ratios (HRs) were obtained. Among 1033 included ECG transmissions, there were 569 (55%) CCL activations and 464 (45%) CCL-NAs (1.8% were inappropriate CCL-NAs). In the CCL activation group, adjudicated index diagnoses included MI (n=534, 94%, of which 99.6% were STEMI and 0.4% non-STEMI), acute myocardial injury (n=15, 2.6%), and chronic myocardial injury (n=6, 1.1%). In the CCL-NA group, diagnoses included MI (n=173, 37%, of which 61% were non-STEMI and 39% STEMI), chronic myocardial injury (n=107, 23%), and acute myocardial injury (n=47, 10%). At 2 years, the risk of all-cause death was higher in patients who had CCL-NA compared with CCL activation (23% versus 7.9%, adjusted risk ratio, 1.58, 95% CI, 1.24-2.00), primarily because of an excess in noncardiovascular deaths (adjusted HR, 3.56, 95% CI, 2.07-6.13). There was no significant difference in the adjusted risk for cardiovascular death/MI/stroke between the 2 groups (HR, 1.23, 95% CI, 0.87-1.73). Conclusions CCL-NA was not primarily attributable to missed STEMI, but attributable to "masquerading" with high rates of non-STEMI and myocardial injury. These patients had worse late outcomes than patients who had CCL activation, mainly because of higher rates of noncardiovascular deaths.

Systematic Review and Meta-Analysis of Diagnostic Accuracy to Identify ST-Segment Elevation Myocardial Infarction on Interpretations of Prehospital Electrocardiograms

Background: The aim of this study was to assess and discuss the diagnostic accuracy of prehospital ECG interpretation through systematic review and meta-analyses.

Methods and Results: Relevant literature published up to July 2020 was identified using PubMed. All human studies of prehospital adult patients suspected of ST-segment elevation myocardial infarction in which prehospital electrocardiogram (ECG) interpretation by paramedics or computers was evaluated and reporting all 4 (true-positive, false-positive, false-negative, and true-negative) values were included. Meta-analyses were conducted separately for the diagnostic accuracy of prehospital ECG interpretation by paramedics (Clinical Question [CQ] 1) and computers (CQ2). After screening, 4 studies for CQ1 and 6 studies for CQ2 were finally included in the meta-analysis. Regarding CQ1, the pooled sensitivity and specificity were 95.5% (95% confidence interval [CI] 82.5–99.0%) and 95.8% (95% CI 82.3–99.1%), respectively. Regarding CQ2, the pooled sensitivity and specificity were 85.4% (95% CI 74.1–92.3%) and 95.4% (95% CI 87.3–98.4%), respectively.

Conclusions: This meta-analysis suggests that the diagnostic accuracy of paramedic prehospital ECG interpretations is favorable, with high pooled sensitivity and specificity, with an acceptable estimated number of false positives and false negatives. Computer-assisted ECG interpretation showed high pooled specificity with an acceptable estimated number of false positives, whereas the pooled sensitivity was relatively low.

Interobserver Variability Among Experienced Electrocardiogram Readers To Diagnose Acute Thrombotic Coronary Occlusion In Patients with Out of Hospital Cardiac Arrest: Impact of Metabolic Milieu and Angiographic Culprit

OBJECTIVES

We sought to evaluate interobserver concordance among experienced electrocardiogram (ECG) readers in predicting acute thrombotic coronary occlusion (ATCO) in the context of abnormal metabolic milieu (AMM) following resuscitated out of hospital cardiac arrest (OHCA).

METHODS

OHCA patients with initial shockable rhythm who underwent invasive coronary angiography (ICA) were included. AMM was defined as one of: pH < 7.1, lactate > 2 mmol/L, serum potassium < 2.8 or > 6.0 mEq/L. The initial ECG following ROSC but prior to ICA was adjudicated by 2 experienced readers using classic ST elevation myocardial infarction [STEMI] and expanded criteria and their combination to predict ATCO on ICA.

RESULTS

152 consecutive patients (mean age 58 years, 76% male) met inclusion criteria. AMM was present in 77%; and 42% had ATCO on ICA. Sensitivity, specificity, PPV, NPV using classic STEMI criteria were 50%, 98%, 94%, 72% (c-statistic 0.74); whereas for combined (STEMI + expanded) criteria they were 69%, 88%, 81%, 79% respectively (c-statistic 0.79). Inter-observer agreement (kappa) was 0.7 for classic STEMI criteria, and 0.66 for combined criteria. Agreement between readers was consistently higher when ATCO was absent and with NMM (kappa 0.78), but lower in AMM (kappa 0.6).

CONCLUSIONS

Despite experienced ECG readers, there was only modest overall concordance in predicting ATCO in the context of resuscitated OHCA. Significant interobserver variations were noted dependent on metabolic milieu and angiographic ATCO. These observations fundamentally question the role of the 12-lead ECG as primary triaging tool for early angiography among patients with OHCA.

Impact of Pre-Hospital Activation of STEMI on False Positive Activation Rate and Door to Balloon Time

BACKGROUND

Pre-hospital identification of ST-segment elevation myocardial infarction (STEMI) by paramedical staff reduces reperfusion time. However, the impact of this approach on the rate of unnecessary activation of coronary catheterisation lab (CCL) remains unclear.

METHODS

The study reviewed consecutive STEMI patients over 3 years (July 2015 to June 2018) from all primary percutaneous coronary intervention (PPCI) centres and inter-hospital transfers (IHT) from non-PPCI capable centres in Western Australia. Out-of-hospital cardiac arrests (OOHCA) and STEMI calls for in-patients receiving treatment for other medical reasons were excluded.

RESULTS

During the 3 years study period, 1,736 STEMI cases were recorded. Pre-hospital (PH) activation occurred in 799 (46%) cases. Median door to balloon time (D2BT) was 68 minutes (IQR 63 mins). D2BT for PH activation (40 min [IQR 25 min]) was significantly lower than both the PPCI centre emergency department (ED) activation (86 min [IQR 55 min]) and IHT activation groups (108 min [IQR 55 min]), p-value <0.00001. In PH activation group 98% patients received primary PCI in less than 90 minutes compared to 54% and 26% patients in the ED and the IHT activation groups, respectively. False positive STEMI activation rate was lower in the PH activation group (2.75%) compared to ED activation (5.4%) and IHT group (6%), p-value 0.0115. The false positive rate did not vary significantly between working hours and out-of-hour calls (5% vs 4%, p-value=0.304). Pericarditis, coronary artery disease other than STEMI, atypical chest pain, and stress induced cardiomyopathy were the common diagnoses in false positive activations.

CONCLUSION

Pre-hospital activation of STEMI leads to reduced door to balloon times without a significant increase in inappropriate procedures, though false positive activation rates are unclear. The majority of STEMI patients transferred from non-PPCI centres failed to receive reperfusion therapy within 90 minutes of initial hospital presentation. Further studies are required to assess the benefits of thrombolysis in selected patients in inter-hospital transfer group.

Rational and design of ST-segment elevation not associated with acute cardiac necrosis (LESTONNAC). A prospective registry for validation of a deep learning system assisted by artificial intelligence

BACKGROUND

Patients with chest pain and persistent ST segment elevation (STE) may not have acute coronary occlusions or serum troponin curves suggestive of acute necrosis. Our objective is the validation and cost-effectiveness analysis of a diagnostic model assisted by artificial intelligence (AI).

METHODS

Prospective multicenter registry in two groups of patients with STE: I) coronary arteries without significant lesions and without serum troponin curve suggestive of acute necrosis, II) myocardial infarction with acute coronary occlusion. The inclusion criteria are the following: 1) age ≥ 18 years, 2) chest pain or symptoms suggestive of myocardial ischemia, 3) STE at point J in two contiguous leads ≥0.1 mV, in V2 and V3 ≥ 0,2 mV and 4) signature of informed consent. The exclusion criteria are the following: 1) left bundle branch block, 2) acute cardiac necrosis in the absence of significant epicardial coronary artery stenosis, 3) STE ≤ 0.1 mV with pathologic Q wave, 4) severe anemia (hemoglobin <8.0 g/dl). For each patient without acute cardiac necrosis, the next patient from that center of the same sex and similar age (± 5 years) with myocardial infarction and acute coronary occlusion will be included. A manual centralized electrocardiographic analysis and another by deep learning AI will be performed.

CONCLUSIONS

The results of the study will provide new information for the stratification of patients with STE. Our hypothesis is that an AI analysis of the surface electrocardiogram allows a better distinction of patients with STE due to acute myocardial ischemia, from those with another etiology.

Likelihood of myocardial infarction, revascularization and death following catheterization laboratory activation in patients with vs. without both chest pain and ST elevation

BACKGROUND

Emergent cardiac catheterization laboratory activation (CCLA) for patients with suspected ST-elevation myocardial infarction (STEMI) is employed to expedite acute revascularization (AR). The incidence of false-positive CCLA, in which AR is not performed, remains high. The combination of chest pain (CP) and electrocardiographic ST elevation (STE) are the hallmarks of STEMI. However, CCLA is sometimes initiated for patients lacking this combination. The study objective was to quantify the difference in likelihood of AR and mortality in patients with vs. without both CP and STE.

METHODS

Retrospective analysis of 1621 consecutive patients for whom CCLA was initiated in a six-hospital network. We assessed the likelihood of acute myocardial infarction (AMI), presence of a culprit lesion (CL), performance of AR, and hospital mortality among patients with both CP and STE (+CP/+STE) compared with patients lacking one or both [non(CP/STE)].

RESULTS

87.0% of patients presented with CP, 82.4% with STE, and 73.7% with both. Among +CP/+STE patients, AMI was confirmed in 90.4%, a CL in 88.9%, and AR performed in 83.1%. The corresponding values among non(CP/STE) patients were 35.8, 31.9, and 28.1%, respectively (P < 0.0001 for each). Nevertheless, mortality among non(CP/STE) patients was three-fold higher than in +CP/+STE patients (13.3% vs. 4.5%; P < 0.0001), with non-coronary deaths 24-fold more likely.

CONCLUSION

Patients lacking the combination of CP and STE have a markedly lower likelihood of AMI and AR than +CP/+STE patients, but significantly higher mortality. Protocols aimed at rapid, focused evaluation of non(CP/STE) patients prior to CCLA are needed.

Effect of Real-Time Physician Oversight of Prehospital STEMI Diagnosis on ECG-Inappropriate and False Positive Catheterization Laboratory Activation

Background

ST-elevation myocardial infarction diagnosis at first medical contact (FMC) and prehospital cardiac catheterization laboratory (CCL) activation are associated with reduced total ischemic time and therefore have become the dominant ST-elevation myocardial infarction referral method in primary percutaneous coronary intervention systems. We sought to determine whether physician oversight was associated with improved diagnostic performance in a prehospital CCL activation system and what effect the additional interpretation has on treatment delay.

Methods

Between 2012 and 2015, all patients in 2 greater Montreal catchment areas with a chief symptom of chest paint or dyspnea had an in-the-field electrocardiogram (ECG). A machine diagnosis of "acute myocardial infarction" resulted either in automatic CCL (automated cohort without oversight) or transmission of the ECG to the receiving centre emergency physician for reinterpretation before CCL activation. System performance was assessed in terms of the proportion of false positive and inappropriate activations (IA), as well as the proportion of patients with FMC-to-device times ≤ 90 minutes.

Results

Four hundred twenty-eight (428) activations were analyzed (311 automated; 117 with physician oversight). Physician oversight tended to decrease IAs (7% vs 3%; P = 0.062), but was also associated with a smaller proportion of patients achieving target FMC-to-device (76% vs 60%; P < 0.001). There was no significant effect on the proportion of false positive activation.

Conclusions

Real-time physician oversight might be associated with fewer IAs, but also appears to have a deleterious effect on FMC-to-device performance. Identifying predictors of IA could improve overall performance by selecting ECGs that merit physician oversight and streamlining others. Larger clinical studies are warranted.

Heat map visualization for electrocardiogram data analysis

BACKGROUND

Most electrocardiogram (ECG) studies still take advantage of traditional statistical functions, and the results are mostly presented in tables, histograms, and curves. Few papers display ECG data by visual means. The aim of this study was to analyze and show data for electrocardiographic left ventricular hypertrophy (LVH) with ST-segment elevation (STE) by a heat map in order to explore the feasibility and clinical value of heat mapping for ECG data visualization.

METHODS

We sequentially collected the electrocardiograms of inpatients in the First Affiliated Hospital of Shantou University Medical College from July 2015 to December 2015 in order to screen cases of LVH with STE. HemI 1.0 software was used to draw heat maps to display the STE of each lead of each collected ECG. Cluster analysis was carried out based on the heat map and the results were drawn as tree maps (pedigree maps) in the heat map.

RESULTS

In total, 60 cases of electrocardiographic LVH with STE were screened and analyzed. STE leads were mainly in the V₁, V₂ and V₃ leads. The ST-segment shifts of each lead of each collected ECG could be conveniently visualized in the heat map. According to cluster analysis in the heat map, STE leads were clustered into two categories, comprising of the right precordial leads (V₁, V₂, V₃) and others (V₄, V₅, V₆, I, II, III, aVF, aVL, aVR). Moreover, the STE amplitude in 40% (24 out of 60) of cases reached the threshold specified in the STEMI guideline. These cases also could be fully displayed and visualized in the heat map. Cluster analysis in the heat map showed that the III, aVF and aVR leads could be clustered together, the V₁, V₂, V₃ and V₄ leads could be clustered together, and the V₅, V₆, I and aVL leads could be clustered together.

CONCLUSION

Heat maps and cluster analysis can be used to fully display every lead of each electrocardiogram and provide relatively comprehensive information.

Implementation of Best Practices-Developing and Optimizing Regional Systems of Stroke Care: Design and Methodology

The AHA Guidelines recommend developing multi-tiered systems for the care of patients with acute stroke.¹ An ideal stroke system of care should ensure that all patients receive the most efficient and timely care, regardless of how they first enter or access the medical care system. Coordination among the components of a stroke system is the most challenging but most essential aspect of any system of care. The Implementation of Best Practices For Acute Stroke Care-Developing and Optimizing Regional Systems of Stroke Care (IMPROVE Stroke Care) project, is designed to implement existing guidelines and systematically improve the acute stroke system of care in the Southeastern United States. Project participation includes 9 hub hospitals, approximately 80 spoke hospitals, numerous pre-hospital agencies (911, fire, and emergency medical services) and communities within the region. The goal of the IMPROVE Stroke program is to develop a regional integrated stroke care system that identifies, classifies, and treats acute ischemic stroke patients more rapidly and effectively with reperfusion therapy. The project will identify gaps and barriers to implementation of stroke systems of care, leverage existing resources within the regions, aid in designing strategies to improve care processes, bring regional representatives together to agree on and implement best practices, protocols, and plans based on guidelines, and establish methods to monitor quality of care. The impact of implementation of stroke systems of care on mortality and long-term functional outcomes will be measured.

A Statewide Assessment of Prehospital Electrocardiography Approaches of Acquisition and Interpretation for ST-Elevation Myocardial Infarction Based on Emergency Medical Services Characteristics

Background: The American Heart Association recommends acquiring and interpreting prehospital electrocardiograms (ECG) for patients transported by Emergency Medical Services (EMS) to the emergency department with symptoms highly suspicious of acute coronary syndrome. If interpreted correctly, prehospital ECGs have the potential to improve early detection of ST-elevation myocardial infarction (STEMI) and inform prehospital activation of the cardiac catheterization laboratory, thus reducing total ischemic time and improving patient outcomes. Standardized protocols for prehospital ECG interpretation methods are lacking due to variations in EMS system design, training, and procedures. Objectives: We aimed to describe approaches for prehospital ECG interpretation in EMS systems across North Carolina (NC), and examine potential differences among systems. Methods: A 35-item internet survey was sent to all NC EMS systems (n = 99). Questions pertaining to prehospital ECG interpretation methods included: paramedic, computerized algorithm (i.e., software interpretation), combined approaches, and/or transmission for physician interpretation, transmission capability, cardiac catheterization laboratory activation, and EMS system characteristics (e.g. rural versus urban). Data were summarized and compared. Results: A total of 96 EMS systems across NC responded to the survey (97% response rate); of these, 69% were rural. EMS medical directors (53%) or EMS administrative directors (42%) completed the majority of surveys. While 91% of EMS systems had a prehospital ECG interpretation protocol in place, only 61% had a written cardiac catheterization laboratory activation policy. More than half (55%) of systems reported paramedic interpretation of prehospital ECGs, followed by a combined paramedic and software interpretation approach (39%), physician interpretation (4%), or software interpretation only approach (2%). Nearly 80% of EMS systems transmitted prehospital ECGs to receiving hospitals (always or sometimes), regardless of interpretation method. All EMS systems had some paid versus non-paid EMS personnel and the majority (86%) had both basic and advanced life support capabilities. Conclusions: Most NC EMS systems had a paramedic only ECG interpretation or paramedic in combination with a computerized algorithm approach. Very few used a physician read approach following transmission, even in rural service areas.

Cancellation of the Cardiac Catheterization Lab After Activation for ST-Segment-Elevation Myocardial Infarction

BACKGROUND

Prehospital ECG-based cardiac catheterization laboratory (CCL) activation for ST-segment-elevation myocardial infarction reduces door-to-balloon times, but CCL cancellations (CCL^X) remain a challenging problem. We examined the reasons for CCL^X, clinical characteristics, and outcomes of patients presenting as ST-segment-elevation myocardial infarction activations who receive emergent coronary angiography (EA) compared with CCL^X.

METHODS AND RESULTS

We reviewed all consecutive CCL activations between January 1, 2012, and December 31, 2014 (n=1332). Data were analyzed comparing 2 groups stratified as EA (n=466) versus CCL^X (n=866; 65%). Reasons for CCL^X included bundle branch block (21%), poor-quality prehospital ECG (18%), non-ST-segment-elevation myocardial infarction ST changes (18%), repolarization abnormality (13%), and arrhythmia (8%). A multivariate logistic regression model using age, peak troponin, and initial ECG findings had a high discriminatory value for determining EA versus CCL^X (C statistic, 0.985). CCL^X subjects were older and more likely to be women, have prior coronary artery bypass grafting, or a paced rhythm ( P<0.0001 for all). All-cause mortality did not differ between groups at 1 year or during the study period (mean follow-up, 2.186±1.167 years; 15.8% EA versus 16.2% CCL^X; P=0.9377). Cardiac death was higher in the EA group (11.8% versus 3.0%; P<0.0001). After adjusting for clinical variables associated with survival, CCL^X was associated with an increased risk for all-cause mortality during the study period (hazard ratio, 1.82; 95% CI, 1.28-2.59; P=0.0009).

CONCLUSIONS

In this study, prehospital ECG without overreading or transmission lead to frequent CCL^X. CCL^X subjects differ with regard to age, sex, risk factors, and comorbidities. However, CCL^X patients represent a high-risk population, with frequently positive cardiac enzymes and similar short- and long-term mortality compared with EA. Further studies are needed to determine how quality improvement initiatives can lower the rates of CCL^X and influence clinical outcomes.

Sensitivity and specificity of the Vectraplex electrocardiogram system with a cardiac electric biomarker in the diagnosis of ST-elevation myocardial infarction

ST-elevation myocardial infarction (STEMI) is a clinical diagnosis based on a compatible history and characteristic electrocardiographic changes. In the current era, STEMI is treated emergently with angiography, leading to percutaneous coronary intervention. However, false-positive electrocardiograms (ECGs) occur, resulting in unnecessary emergent catheterizations. We hypothesized that the Vectraplex cardiac electrical biomarker (CEB) would increase the specificity for the diagnosis of STEMI. We studied 50 patients who were identified by standard of care (clinical history, physical exam, and 12-lead ECG) as suspected to have STEMI and tested the sensitivity and specificity of the Vectraplex ECG system. Using the final clinical diagnosis (based on history, ECGs, troponin values, and angiographic findings) as the gold standard, we found the CEB value to be quite dynamic, with a reasonable sensitivity and a good positive predictive value but generally poor specificity and negative predictive value. It offered only a 20% improvement compared to 50-50 performance on receiver operator curves.

Paramedic-initiated helivac to tertiary hospital for primary percutaneous coronary intervention: a strategy for improving treatment delivery times

Background

In regions of New Zealand without coronary catheterisation laboratory (CCL) facilities, patients presenting with ST-elevation myocardial infarction (STEMI) are often subjected to prolonged delays before receiving primary percutaneous coronary intervention (PPCI) if it is the chosen reperfusion strategy. Therefore, we aimed to trial a new process of paramedic-initiated helivac of STEMI patients from the field directly to the CCL.

Methods

Utilising a prospective observational approach, over a 48-month period, paramedics identified patients with a clinical presentation and electrocardiogram features consistent with STEMI and transported them directly to the regional air ambulance base for helivac to the CCL (flight time 30-35 minutes). These patients were compared to two historic STEMI cohorts either transported by paramedics to the region's local hospital or self-presenting, prior to helivac. The primary outcome measures were: first medical contact-to-balloon (FMCTB) time and accuracy of paramedic diagnosis. Secondary outcome measures were mortality at 30 days and six months, and hospital length of stay (LOS).

Results

A total of 92 patients underwent helivac for PPCI (mean age of 64 years, SD ±10.3). Median FMCTB time was 155 minutes (IQR 27) for the historic cohorts (n=57), versus 102 minutes (IQR 16) for the experimental cohort (n=35, P<0.001). Paramedic diagnosis showed a sensitivity of 97% (95% CI: 85 to 99) and a specificity of 100% (95% CI: 84 to 100) with no inappropriate CCL activations. No significant difference was observed between groups in terms of 30 day and 6-month mortality. Hospital LOS was significantly shorter among the experimental cohort (P=0.01).

Conclusions

Paramedic-initiated helivac of STEMI patients from the field directly to the CCL for PPCI is safe and feasible and can significantly improve time-to-treatment to within benchmark timeframes, resulting in reduced hospital LOS.

Diagnostic accuracy of prehospital electrocardiograms interpreted remotely by emergency physicians in myocardial infarction patients

BACKGROUND

Prehospital 12‑lead electrocardiogram (ECG) is the most widely used screening tool for recognition of ST-segment elevation myocardial infarction (STEMI). However, prehospital diagnosis of STEMI based solely on ECGs can be challenging.

OBJECTIVES

To evaluate the ability of emergency department (ED) physicians to accurately interpret prehospital 12‑lead ECGs from a remote location.

METHODS

All suspected prehospital STEMI patients who were transported by EMS and underwent angiography between 2006 and 2014 were included. We reviewed prehospital ECGs and grouped them based on: 1) presence or absence of a culprit artery lesion following angiography; and 2) whether they met the 3rd Universal Definition of Myocardial Infarction. We also described characteristics of ECGs that were misinterpreted by ED physicians.

RESULTS

A total of 625 suspected STEMI cases were reviewed. Following angiography, 94% (590/625) of patients were found having a culprit artery lesion, while 6% (35/625) did not. Among these 35 patients, 24 had ECGs that mimicked STEMI criteria and 9 had non-ischemic signs. Upon ECG reinterpretation, 92% (577/625) had standard STEMI criteria while 8% (48/625) did not. Among these 48 patients, 35 had ischemic signs ECGs and 13 did not. Characteristics of misinterpreted ECGs included pericarditis, early repolarization, STE > 1 mm (1‑lead only), and negative T-wave.

CONCLUSIONS

Remote interpretation of prehospital 12‑lead ECGs by ED physicians was a useful diagnostic tool in this EMS system. Even if the rate of ECG misinterpretation is low, there is still room for ED physicians operating from a remote location to improve their ability to accurately diagnose STEMI patients.

The effects of prearrival direct notification call to interventional cardiologist on door-to-balloon time in patients who required secondary diversion with ST-elevation myocardial infarction for primary percutaneous coronary intervention

Background:

Rapid door-to-balloon times in ST-elevation myocardial infarction patients undergoing primary percutaneous coronary intervention are associated with favorable outcomes.

Objectives:

We evaluated the effects of prearrival direct notification calls to interventional cardiologists on door-to-balloon time for ST-elevation myocardial infarction patients undergoing primary percutaneous coronary intervention.

Methods:

A 24-h hotline was created to allow prearrival direct notification calls to interventional cardiologists when transferring ST-elevation myocardial infarction patients. In an urban, tertiary referral center, patients who visited via inter-facility or the emergency department directly were included. Clinical parameters, time to reperfusion therapy, and in-hospital mortality were compared between patients with and without prearrival notifications.

Results:

Of 228 ST-elevation myocardial infarction patients, 95 (41.7%) were transferred with prearrival notifications. In these patients, door-to-balloon time was shorter (50.0 vs 60.0 min, p = 0.010) and the proportion of patients with door-to-balloon time < 90 min was higher (89.5% vs 75.9%, p = 0.034) than patients without notifications. These improvements were more pronounced during “off-duty” hours (52.0 vs 78.0 min, p = 0.001; 88.3% vs 72.3%, p = 0.047, respectively) than during “on-duty” hours (37.5 vs 43.5 min, p = 0.164; 94.4% vs 79.4%, p = 0.274, respectively). In addition, door-to-activation time (–39 vs 11 min, p < 0.001) and door-to-catheterization laboratory arrival time (33 vs 42 min, p = 0.007) were shorter in patients with prearrival notifications than those without. However, in-hospital mortality was similar between the two groups (6.3% vs 6.8%, p = 0.892).

Conclusion:

Prearrival direct notification calls to interventional cardiologists significantly improved the door-to-balloon time and the proportion of patients with door-to-balloon time < 90 min through rapid patient transport in primary percutaneous coronary intervention scheduled hospital and readiness of the catheterization laboratory.

Impact of Regionalization of ST-Segment–Elevation Myocardial Infarction Care on Treatment Times and Outcomes for Emergency Medical Services–Transported Patients Presenting to Hospitals With Percutaneous Coronary Intervention

Background:

Regional variations in reperfusion times and mortality in patients with ST-segment–elevation myocardial infarction are influenced by differences in coordinating care between emergency medical services (EMS) and hospitals. Building on the Accelerator-1 Project, we hypothesized that time to reperfusion could be further reduced with enhanced regional efforts.

Methods:

Between April 2015 and March 2017, we worked with 12 metropolitan regions across the United States with 132 percutaneous coronary intervention–capable hospitals and 946 EMS agencies. Data were collected in the ACTION (Acute Coronary Treatment and Intervention Outcomes Network)-Get With The Guidelines Registry for quarterly Mission: Lifeline reports. The primary end point was the change in the proportion of EMS-transported patients with first medical contact to device time ≤90 minutes from baseline to final quarter. We also compared treatment times and mortality with patients treated in hospitals not participating in the project during the corresponding time period.

Results:

During the study period, 10 730 patients were transported to percutaneous coronary intervention–capable hospitals, including 974 in the baseline quarter and 972 in the final quarter who met inclusion criteria. Median age was 61 years; 27% were women, 6% had cardiac arrest, and 6% had shock on admission; 10% were black, 12% were Latino, and 10% were uninsured. By the end of the intervention, all process measures reflecting coordination between EMS and hospitals had improved, including the proportion of patients with a first medical contact to device time of ≤90 minutes (67%–74%; P <0.002), a first medical contact to device time to catheterization laboratory activation of ≤20 minutes (38%–56%; P <0.0001), and emergency department dwell time of ≤20 minutes (33%–43%; P <0.0001). Of the 12 regions, 9 regions reduced first medical contact to device time, and 8 met or exceeded the national goal of 75% of patients treated in ≤90 minutes. Improvements in treatment times corresponded with a significant reduction in mortality (in-hospital death, 4.4%–2.3%; P =0.001) that was not apparent in hospitals not participating in the project during the same time period.

Conclusions:

Organization of care among EMS and hospitals in 12 regions was associated with significant reductions in time to reperfusion in patients with ST-segment–elevation myocardial infarction as well as in in-hospital mortality. These findings support a more intensive regional approach to emergency care for patients with ST-segment–elevation myocardial infarction.

Detection of STEMI Using Prehospital Serial 12-Lead Electrocardiograms

OBJECTIVE

Repeated or serial 12-lead electrocardiograms (ECGs) in the prehospital setting may improve management of patients with subtle ST-segment elevation (STE) or with a ST-segment elevation myocardial infarction (STEMI) that evolves over time. However, there is a minimal amount of scientific evidence available to support the clinical utility of this method. Our objective was to evaluate the use of serial 12-lead ECGs to detect STEMI in patients during transport in a Canadian emergency medical services (EMS) jurisdiction.

METHODS

We performed a retrospective study of suspected STEMI patients transported by EMS in the Chaudière-Appalaches region (Québec, Canada) between August 2006 and December 2013. Patients were monitored by a serial 12-lead ECG system where an averaged ECG was transmitted every 2 minutes. Following review by an emergency physician, ECGs were grouped as having either a persistent STE or a dynamic STE that evolved over time.

RESULTS

A total of 754 suspected STEMI patients were transported by EMS during the study period. Of these, 728 patients met eligibility criteria and were included in the analysis. A persistent STE was observed in 84.3% (614/728) of patients, while the remaining 15.7% (114/728) had a dynamic STE. Among those with dynamic STE, 11.1% (81/728) had 1 ST-segment change (41 no-STEMI to STEMI; 40 STEMI to no-STEMI) and 4.5% (33/728) had ≥ 2 ST-segment changes (17 no-STEMI to STEMI; 16 STEMI to no-STEMI). Overall, in 8.0% (58/728) of the cohort, STEMI was identified on a subsequent ECG following an initial no-STEMI ECG.

CONCLUSIONS

Through recognition of transient ST-segment changes during transport via the prehospital serial 12-lead ECG system, STEMI was identified in 8% of suspected STEMI patients who had an initial no-STEMI ECG. Key words: electrocardiography; emergency medical services; ST-elevation myocardial infarction; prehospital dynamic ECG.

False Positive STEMI Activations in a Regional Network: Comprehensive Analysis and Clinical Impact. Results From the Catalonian Codi Infart Network

INTRODUCTION AND OBJECTIVES

ST-segment elevation myocardial infarction (STEMI) network activation by a noncardiologist reduces delay times but may increase the rate of false-positive STEMI diagnoses. We aimed to determine the prevalence, predictors, and clinical impact of false-positive activations within the Catalonian STEMI network (Codi Infart).

METHODS

From January 2010 through December 2011, all consecutive patients treated within the Codi Infart network were included. Code activations were classified as appropriate if they satisfied both electrocardiogram and clinical STEMI criteria. Appropriate activations were classified as false positives using 2 nonexclusive definitions: a) "angiographic" if a culprit coronary artery was not identified, and b) "clinical" if the discharge diagnosis was other than STEMI.

RESULTS

In total, 5701 activations were included. Appropriate activation was performed in 87.8% of the episodes. The rate of angiographic false positives was 14.6%, while the rate of clinical false positives was 11.6%. Irrespective of the definition, female sex, left bundle branch block, and previous myocardial infarction were independent predictors of false-positive STEMI diagnoses. Using the clinical definition, hospitals without percutaneous coronary intervention and patients with complications during the first medical contact also had a false-positive STEMI diagnoses rate higher than the mean. In-hospital and 30-day mortality rates were similar for false-positive and true-positive STEMI patients after adjustment for possible confounders.

CONCLUSIONS

False-positive STEMI diagnoses were frequent. Outcomes were similar for patients with a true-positive or false-positive STEMI diagnosis treated within a STEMI network. The presence of any modifiable predictors of a false-positive STEMI diagnosis warrants careful assessment to optimize the use of STEMI networks.

False Activations for ST-Segment Elevation Myocardial Infarction

First-medical-contact-to-device (FMC2D) times have improved over the past decade, as have clinical outcomes for patients presenting with ST-elevation myocardial infarction (STEMI). However, with improvements in FMC2D times, false activation of the cardiac catheterization laboratory (CCL) has become a challenging problem. The authors define false activation as any patient who does not warrant emergent coronary angiography for STEMI. In addition to clinical outcome measures for these patients, STEMI systems should collect data regarding the total number of CCL activations, the total number of emergency coronary angiograms, and the number revascularization procedures performed.

A new 4-variable formula to differentiate normal variant ST segment elevation in V2-V4 (early repolarization) from subtle left anterior descending coronary occlusion - Adding QRS amplitude of V2 improves the model

INTRODUCTION

Precordial normal variant ST elevation (NV-STE), previously often called "early repolarization," may be difficult to differentiate from subtle ischemic STE due to left anterior descending (LAD) occlusion. We previously derived and validated a logistic regression formula that was far superior to STE alone for differentiating the two entities on the ECG. The tool uses R-wave amplitude in lead V4 (RAV4), ST elevation at 60 ms after the J-point in lead V3 (STE60V3) and the computerized Bazett-corrected QT interval (QTc-B). The 3-variable formula is: 1.196 x STE60V3 + 0.059 × QTc-B - 0.326 × RAV4 with a value ≥23.4 likely to be acute myocardial infarction (AMI).

HYPOTHESIS

Adding QRS voltage in V2 (QRSV2) would improve the accuracy of the formula.

METHODS

355 consecutive cases of proven LAD occlusion were reviewed, and those that were obvious ST elevation myocardial infarction were excluded. Exclusion was based on one straight or convex ST segment in V2-V6, 1 millimeter of summed inferior ST depression, any anterior ST depression, Q-waves, "terminal QRS distortion," or any ST elevation >5 mm. The NV-STE group comprised emergency department patients with chest pain who ruled out for AMI by serial troponins, had a cardiologist ECG read of "NV-STE," and had at least 1 mm of STE in V2 and V3. R-wave amplitude in lead V4 (RAV4), ST elevation at 60 ms after the J-point in lead V3 (STE60V3) and the computerized Bazett-corrected QT interval (QTc-B) had previously been measured in all ECGs; physicians blinded to outcome then measured QRSV2 in all ECGs. A 4-variable formula was derived to more accurately classify LAD occlusion vs. NV-STE and optimize area under the curve (AUC) and compared with the previous 3-variable formula.

RESULTS

There were 143 subtle LAD occlusions and 171 NV-STE. A low QRSV2 added diagnostic utility. The derived 4-variable formula is: 0.052*QTc-B - 0.151*QRSV2 - 0.268*RV4 + 1.062*STE60V3. The 3-variable formula had an AUC of 0.9538 vs. 0.9686 for the 4-variable formula (p = 0.0092). At the same specificity as the 3-variable formula [90.6%, at which cutpoint (≥23.4), 123 of 143 MI were correctly classified for 86% sensitivity], the sensitivity of the new formula at cutpoint ≥17.75 is 90.2%, with 129/143 correctly classified MI, identifying an additional 6 cases. The cutpoint with the highest accuracy (92.0%) was at a cutoff value ≥18.2, with 88.8% sensitivity, 94.7% specificity, and a positive and negative likelihood ratio of 16.9 (95% CI: 8.9-32) and 0.12 (95% CI: 0.07-0.19). At this cutpoint, it correctly classified an additional 11 cases (289 of 315, vs. 278 of 315): 127/143 for MI (an additional 4 cases) and 162/171 for NV-STE (an additional 7 cases).

CONCLUSION

On the ECG, a 4-variable formula was derived which adds QRSV2; it differentiates subtle LAD occlusion from NV-STE better than the 3-variable formula. At a value ≥18.2, the formula (0.052*QTc-B - 0.151*QRSV2 - 0.268*RV4 + 1.062*STE60V3) was very accurate, sensitive, and specific, with excellent positive and negative likelihood ratios. This formula needs to be validated.

Effectiveness of a Prehospital Wireless 12-Lead Electrocardiogram and Cardiac Catheterization Laboratory Activation for ST-Elevation Myocardial Infarction

The aim of the study was to determine the prevalence of false-positive and inappropriate cardiac catheterization laboratory (CCL) activation in patients suspected with ST-elevation myocardial infarction (STEMI) diverted to a percutaneous coronary intervention (PCI) facility after paramedics wireless 12-lead electrocardiogram transmission to an emergency physician at an online medical control center. This retrospective study collected data from medical records of patients with suspected STEMI from 2006 to 2014. It included demographics, coronaropathic risk factors, cardiac biomarkers, time from the first medical contact to treatment, and final diagnosis. Primary outcome was the rate of false-positive and inappropriate CCL activation. As secondary outcomes, we compared patient characteristics between cases of appropriate and inappropriate CCL activation, and we assessed the presence of cardiac biomarkers, time from first medical contact to start of PCI, and final diagnosis. Overall, 673 patients with suspected STEMI were included in the analysis. A total of 640 patients (95%) had coronarography, of which 10% (62 of 640) did not have a culprit coronary artery (false positive). Angiography was canceled for 5% (33 of 673) of patients. The total false-positive and inappropriate CCL activation rate was 14% (95 of 673). Average time from the first medical contact to the start of PCI was 47 ± 18.1 minutes. Unwanted CCL activations were more likely to involve men aged >65 years and patients with a history of coronary artery disease. In conclusion, our system of transmitted prehospital electrocardiography and STEMI interpretation by emergency physicians at an online medical control center showed a total false-positive and inappropriate CCL activation rate of 14% over the 8-year study period.

Sustained Performance of a "Physicianless" System of Automated Prehospital STEMI Diagnosis and Catheterization Laboratory Activation

BACKGROUND

Treatment times for primary percutaneous coronary intervention frequently exceed the recommended maximum delay. Automated "physicianless" systems of prehospital cardiac catheterization laboratory (CCL) activation show promise, but have been met with resistance over concerns regarding the potential for false positive and inappropriate activations (IAs).

METHODS

From 2010 to 2015, first responders performed electrocardiograms (ECGs) in the field for all patients with a complaint of chest pain or dyspnea. An automated machine diagnosis of "acute myocardial infarction" resulted in immediate CCL activation and direct transfer without transmission or human reinterpretation of the ECG prior to patient arrival. Any activation resulting from a nondiagnostic ECG (no ST-elevation) was deemed an IA, whereas activations resulting from ECG's compatible with ST-elevation myocardial infarction but without angiographic evidence of a coronary event were deemed false positive. In 2012, the referral algorithm was modified to exclude supraventricular tachycardia and left bundle branch block.

RESULTS

There were 155 activations in the early cohort (2010-2012; prior to algorithm modification) and 313 in the late cohort (2012-2015). Algorithm modification resulted in a 42% relative decrease in the rate of IAs (12% vs 7%; P < 0.01) without a significant effect on treatment delay.

CONCLUSIONS

A combination of prehospital automated ST-elevation myocardial infarction diagnosis and "physicianless" CCL activation is safe and effective in improving treatment delay and these results are sustainable over time. The performance of the referral algorithm in terms of IA and false positive is at least on par with systems that ensure real-time human oversight.

Initial experience with pre-activation of the cardiac catheterization lab and emergency room bypass for patients with ST-elevation myocardial infarction in Halifax, Nova Scotia

BACKGROUND

To determine whether pre-activation of the cardiac catheterization lab by Emergency Health Services (EHS) with a single call system in the field was associated with reduced time to reperfusion in patients with ST-Elevation Myocardial Infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI).

METHODS

Consecutive STEMI patients identified by EHS and subsequently taken to the Queen Elizabeth II Health Sciences Center (QEIIHSC) for PPCI between February 1, 2011 and January 30, 2013 were examined. Patients who had pre-activation of the catheterization lab from the field (pre-act group) after the acquisition of the LifeNet® system (Physio Control, Redmond Washington) were compared to those who had usual activation (routine group) prior to the acquisition of the LifeNet® system, for outcomes including treatment timeline data and mortality.

RESULTS

271 patients were included in the analysis, 149 patients in the pre-act group and 122 patients in the routine group. Door-to-device (DTD) times of less than 90min were achieved more frequently in the Pre-act group (91.9% vs. 62.2%; P<0.001). DTD time was shorter in the Pre-act group (48min IQR: 38 to 63min vs. 78min IQR: 64-101min; p=0.001) as was first medical contact-to-device (FMCTD) time (91min IQR: 78 to 106min vs. 115min IQR: 90 to 139min; P<0.001). False activation of the catheterization lab was infrequent (1.3%).

CONCLUSIONS

Implementation of catheterization lab pre-activation using the LifeNet® system was associated with more efficient reperfusion times as measured by reduced FMCTD and DTD times without excess false activation rates.

Cardiac Monitoring in the Emergency Department

Patients present to the emergency department (ED) with a wide range of complaints and ED clinicians are responsible for identifying which conditions are life threatening. Cardiac monitoring strategies in the ED include, but are not limited to, 12-lead electrocardiography and bedside cardiac monitoring for arrhythmia and ischemia detection as well as QT-interval monitoring. ED nurses are in a unique position to incorporate cardiac monitoring into the early triage and risk stratification of patients with cardiovascular emergencies to optimize patient management and outcomes.

Frequency and factors associated with inappropriate for intervention cardiac catheterization laboratory activation

BACKGROUND

Current guidelines emphasize timely coronary intervention with a door to balloon time of ≤90min for favorable survival impact after STEMI. Efforts to achieve these targets may result in unnecessary emergent angiography for inappropriate activations.

OBJECTIVE

Evaluate the frequency, trend and factors which are significantly associated with inappropriate for intervention cardiac catheterization laboratory (CCL) activation.

METHODS

We analyzed 1764 consecutive emergent CCL activation for possible ST segment elevation myocardial infarction (STEMI) between 7/2005 and 8/2013. Inappropriate for intervention activation was defined as negative STEMI (incorrect diagnosis: insignificant coronary lesion, not requiring any intervention) and inappropriate patients (true STEMI but poor CCL candidacy).

RESULTS

Inappropriate for intervention CCL activation occurred in 317 patients (17.9%): 292 incorrect diagnosis (negative STEMI diagnosis), 25 inappropriate patients, with no difference in the frequency based on time of the day (18.6% regular hours vs. 17.6% off-hours, p=0.6). On multivariable analysis, female gender (OR 1.9 [1.2-3.0]), African American race (OR 1.9[1.3-2.7]), and prior coronary artery bypass graft surgery (OR 3.6 [2.3-5.5]) were significantly associated with incorrect diagnosis (negative STEMI diagnosis) (all p<0.005) and hyperlipidemia (OR 0.2 [0.1-0.3]), tobacco use (OR 0.2 [0.1-0.3]), and stroke/TIA (OR 0.2 [0.1-0.4]) had a significant inverse association (all p<0.001). ST Elevation with no reciprocal depression and pericarditis/myocarditis were the most common ECG finding and etiology respectively.

CONCLUSION

Inappropriate for intervention CCL activation is not uncommon and should be closely monitored to maximize resource utilization. Females, African American patients with few or no risk factors and patients presenting ST elevation but no reciprocal depression constitute a population that may require attention.

Electrocardiographic diagnosis of ST segment elevation myocardial infarction: An evaluation of three automated interpretation algorithms

OBJECTIVE

To assess the validity of three different computerized electrocardiogram (ECG) interpretation algorithms in correctly identifying STEMI patients in the prehospital environment who require emergent cardiac intervention.

METHODS

This retrospective study validated three diagnostic algorithms (AG) against the presence of a culprit coronary artery upon cardiac catheterization. Two patient groups were enrolled in this study: those with verified prehospital ST-elevation myocardial infarction (STEMI) activation (cases) and those with a prehospital impression of chest pain due to ACS (controls).

RESULTS

There were 500 records analyzed resulting in a case group with 151 patients and a control group with 349 patients. Sensitivities differed between AGs (AG1=0.69 vs AG2=0.68 vs AG3=0.62), with statistical differences in sensitivity found when comparing AG1 to AG3 and AG1 to AG2. Specificities also differed between AGs (AG1=0.89 vs AG2=0.91 vs AG3=0.95), with AG1 and AG2 significantly less specific than AG3.

CONCLUSIONS

STEMI diagnostic algorithms vary in regards to their validity in identifying patients with culprit artery lesions. This suggests that systems could apply more sensitive or specific algorithms depending on the needs in their community.

Incidence and characteristics of inappropriate and false-positive cardiac catheterization laboratory activations in a regional primary percutaneous coronary intervention program

BACKGROUND

The implementation of regional primary percutaneous coronary intervention (PCI) programs has been critical in achieving timely intervention in patients with ST-segment elevation myocardial infarction (STEMI). However, 1 consequence has been inappropriate and false-positive cardiac catheterization laboratory (CCL) activations where either angiography is cancelled or no culprit lesion is found, respectively.

METHODS

We performed a retrospective cohort study of 1,391 patients referred for primary PCI to a single academic center from November 2007 to August 2013. Our purpose was to determine the incidence and characteristics of inappropriate and false-positive CCL activations by emergency departments (EDs) or emergency medical services (EMS), and the effect of a quality improvement (QI) initiative to reduce such events implemented during this period.

RESULTS

During the study period, there were 37 (2.7%) inappropriate and 206 (14.8%) false-positive CCL activations. There was no difference between the ED and EMS rates of inappropriate activation (2.1% vs 3.8%, P = .06). Among patients who proceeded to angiography, the false-positive rate for ED CCL activation was 16.9% compared to 11.5% for EMS (P = .01). Although there was no difference comparing inappropriate activation or false-positive rates before and after the QI initiative (P = .22), we observed an encouraging year-to-year trend.

CONCLUSIONS

Emergency department activation of the CCL is associated with a higher false-positive rate than activation by EMS. Further QI efforts are required to improve communication between interventional cardiologists, emergency physicians, and paramedics to improve the specificity of CCL activation while taking care not to sacrifice sensitivity and rapidity of diagnosis.

Characteristics of ST Elevation Myocardial Infarction Patients Who Do Not Undergo Percutaneous Coronary Intervention After Prehospital Cardiac Catheterization Laboratory Activation

OBJECTIVES

To assess the clinical and electrocardiographic characteristics of patients diagnosed with ST elevation myocardial infarction (STEMI) that are associated with an increased likelihood of not undergoing percutaneous coronary intervention (PCI) after prehospital Cardiac Catheterization Laboratory activation in a regional STEMI system.

METHODS

We performed a retrospective analysis of prehospital Cardiac Catheterization Laboratory activations in Mecklenburg County, North Carolina, between May 2008 and March 2011. Data were extracted from the prehospital patient record, the prehospital electrocardiogram, and the regional STEMI database. The independent variables of interest included objective patient characteristics as well as documented cardiac history and risk factors. Analysis was performed using descriptive statistics and logistic regression.

RESULTS

Two hundred thirty-one prehospital activations were included in the analysis. Five independent variables were found to be associated with an increased likelihood of not undergoing PCI: increasing age, bundle branch block, elevated heart rate, left ventricular hypertrophy, and non-white race. The variables with the most significance were any type of bundle branch block [adjusted odds ratios (AOR), 5.66; 95% confidence interval (CI), 1.91-16.76], left ventricular hypertrophy (AOR, 4.63; 95% CI, 2.03-10.53), and non-white race (AOR, 3.53; 95% CI, 1.76-7.08). Conversely, the only variable associated with a higher likelihood of undergoing PCI was the presence of arm pain (AOR, 2.94; 95% CI, 1.36-6.25).

CONCLUSIONS

Several of the above variables are expected electrocardiogram mimics; however, the decreased rate of PCI in non-white patients highlights an area for investigation and process improvement. This may guide the development of prehospital STEMI protocols, although avoiding false positive and inappropriate activations.

Physician perceptions and recommendations about pre-hospital emergency medical services for patients with ST-elevation acute myocardial infarction in Abu Dhabi

Introduction

Physician perceptions about emergency medical services (EMS) are important determinants of improving pre-hospital care for cardiac emergencies. No data exist on physician attitudes towards EMS care of patients with ST-Elevation Myocardial Infarction (STEMI) in the Emirate of Abu Dhabi.

Objectives

To describe the perceptions towards EMS among physicians caring for patients with STEMI in Abu Dhabi.

Methods

We surveyed a convenience sample of physicians involved in the care of patients with STEMI (emergency medicine, cardiology, cardiothoracic surgery and intensive care) in four government facilities with 24/7 Primary PCI in the Emirate of Abu Dhabi. Surveys were distributed using dedicated email links, and used 5-point Likert scales to assess perceptions and attitudes to EMS.

Results

Of 106 physician respondents, most were male (82%), practicing in emergency medicine (47%) or cardiology (44%) and the majority (63%) had been in practice for >10 years. Less than half of the responders (42%) were “Somewhat Satisfied” (35%) or “Very Satisfied” (7%) with current EMS level of care for STEMI patients. Most respondents were “Very Likely” (67%) to advise a patient with a cardiac emergency to use EMS, but only 39% felt the same for themselves or their family. Most responders were supportive (i.e. “Strongly Agree”) of the following steps to improve EMS care: 12-lead ECG and telemetry to ED by EMS (69%), EMS triage of STEMI to PCI facilities (65%), and activation of PCI teams by EMS (58%). Only 19% were supportive of pre-hospital fibrinolytics by EMS. There were no significant differences in the responses among the specialties.

Conclusions

Most physicians involved in STEMI care in Abu Dhabi are very likely to advise patients to use EMS for a cardiac emergency, but less likely to do so for themselves or their families. Different specialties had concordant opinions regarding steps to improve pre-hospital EMS care for STEMI.

Using EMS Dispatch to Trigger STEMI Alerts Decreases Door-to-Balloon Times

Introduction

We sought to determine the potential reduction in door-to-balloon time (DTB) by allowing paramedics to perform prehospital ST-Elevation Myocardial Infarction (STEMI) notification using brief communications via emergency medical services (EMS) 9-1-1 dispatchers as soon as they saw a STEMI on 12-lead electrocardiogram (EKG). Our hypothesis was that earlier cardiac catheterization lab (CCL) activation would improve overall DTB and avoid delays arising from on-scene issues or the time required to deliver a full report.

Methods

The study setting was a single suburban community teaching hospital, which is a regional percutaneous coronary intervention (PCI) center with more than 120,000 Emergency Department (ED) visits/year and is serviced by a single tiered-response, advanced life support (ALS) paramedic-level agency. STEMI notifications from July 2009 to July 2012 occurred by either standard direct EMS-to-physician notification or by immediate 9-1-1 dispatch notification. In the 9-1-1 dispatcher-aided notification method, paramedics were asked to provide a brief one-sentence report using their lapel microphones upon immediate realization of a diagnostic EKG (usually within 1–2 minutes of patient contact). This report to the 9-1-1 dispatcher included the patient’s sex, age, and cardiologist (if known). The dispatcher then called the emergency department attending and informed them that a STEMI was being transported and that CCL activation was needed. We used retrospective chart review of a consecutive sample of patients from an existing STEMI registry to determine whether there was a statistically significant difference in DTB between the groups.

Results

Eight hundred fifty-six total STEMI alert patients arrived by EMS during the study. We excluded 730 notifications due to events such as cardiac arrest, arrhythmia, death, resolution of EKG changes and/or symptoms, cardiologist decision not to perform PCI, arrival as a transfer after prior stabilization at a referring facility or arriving by an EMS agency other than New Castle County EMS (NCC*EMS). Sixty-four (64) sequential patients from each group comprised the study sample. The average DTB (SD) for the standard communication method was 57.6 minutes (17.9), while that for dispatcher-aided communication was 46.1 minutes (12.8), (mean difference 57.6-46.1 minutes=11.5 minutes with a 95% CI [6.06,16.94]) p=0.0001. In the dispatcher-aided group, 92% of patients (59/64) met standards of ≤60 minute DTB time. Only 64% (41/64) met this goal in the standard communication group (p=0.0001).

Conclusion

Brief, early notification of STEMI by paramedics through 9-1-1 dispatchers achieves earlier CCL activation in a hospital system already using EMS-directed CCL activation. This practice significantly decreased DTB and yielded a higher percentage of patients meeting the DTB≤60 minutes quality metric.

Characteristics of patients with false- ST-segment elevation myocardial infarction diagnoses

BACKGROUND

A subgroup of patients presenting with suspected ST-elevation myocardial infarction (STEMI) have no culprit lesion during coronary angiography (false-positive STEMI). Little is known about patient- and system-related factors that are associated with false-positive STEMI. We evaluated the incidence, correlates, delay, final diagnosis, and outcome of patients with false-positive STEMI.

METHODS

We studied 827 consecutive patients presenting with suspected STEMI between January 2011-September 2012.

RESULTS

A false positive STEMI activation was identified in 68 patients (8.2%). Patients with false-positive STEMI were younger (57 vs 63 year; p=0.020), less often had hypercholesterolemia (19 vs 43%; p=0.001), and had a higher heart rate (82 vs 75 bpm; p=0.014). The association between these factors and false-positive STEMI activation persisted in multivariate analysis. The duration of symptoms to call was longer in false-positive STEMI patients (128 vs 83 min; p=0.030), although this did not reach statistical significance in multivariate analysis. Final diagnosis in patients with false-positive STEMI activation was particularly from unknown origin (41%). There were no significant differences in mortality at 30 days and one year between patients with STEMI and false-positive STEMI.

CONCLUSION

The incidence of false-positive STEMI was 8.2% in patients suspected of STEMI. Patients with false-positive STEMI differ from STEMI patients in certain baseline characteristics and in patient delay. Interestingly, absence of coronary disease did not translate into better clinical outcome.

Reperfusion strategies in acute coronary syndromes

The appropriate timing of angiography to facilitate revascularization is essential to optimize outcomes in patents with ST-segment-elevation myocardial infarction and non-ST-segment-elevation acute coronary syndromes. Timely reperfusion of the infarct-related coronary artery in ST-segment-elevation myocardial infarction both with fibrinolysis or percutaneous coronary intervention minimizes myocardial damage, reduces infarct size, and decreases morbidity and mortality. Primary percutaneous coronary intervention is the preferred reperfusion method if it can be performed in a timely manner. Strategies to reduce health system-related delays in reperfusion include regionalization of ST-segment-elevation myocardial infarction care, performing prehospital ECGs, prehospital activation of the catheterization laboratory, bypassing geographically closer nonpercutaneous coronary intervention-capable hospitals, bypassing the percutaneous coronary intervention-capable hospital emergency department, and early and consistent availability of the catheterization laboratory team. With implementation of such strategies, there has been significant improvement in process measures, including door-to-balloon time. However, despite reductions in door-to-balloon times, there has been little change during the past several years in in-hospital mortality, suggesting additional factors including patient-related delays, optimization of tissue-level perfusion, and cardioprotection must be addressed to improve patient outcomes further. Early angiography followed by revascularization when appropriate also reduces rates of death, MI, and recurrent ischemia in patients with non-ST-segment-elevation acute coronary syndromes, with the greatest benefits realized in the highest risk patients. Among patients with non-ST-segment-elevation acute coronary syndromes with multivessel disease, choice of revascularization modality should be made as in stable coronary artery disease, with a goal of complete ischemic revascularization.

Electrocardiograhic findings resulting in inappropriate cardiac catheterization laboratory activation for ST-segment elevation myocardial infarction

BACKGROUND

Prompt reperfusion has been shown to improve outcomes in patients with acute ST-segment elevation myocardial infarction (STEMI) with a goal of culprit vessel patency in <90 minutes. This requires a coordinated approach between the emergency medical services (EMS), emergency department (ED) and interventional cardiology. The urgency of this process can contribute to inappropriate cardiac catheterization laboratory (CCL) activations.

OBJECTIVES

One of the major determinants of inappropriate activations has been misinterpretation of the electrocardiogram (ECG) in the patient with acute chest pain.

METHODS

We report the ECG findings for all CCL activations over an 18-month period after the inception of a STEMI program at our institution.

RESULTS

There were a total of 139 activations with 77 having a STEMI diagnosis confirmed and 62 activations where there was no STEMI. The inappropriate activations resulted from a combination of atypical symptoms and misinterpretation of the ECG (45% due to anterior ST-segment elevation) on patient presentation. The electrocardiographic abnormalities were particularly problematic in African-Americans with left ventricular hypertrophy.

CONCLUSIONS

In this single-center, prospective observational study, nearly half of the inappropriate STEMI activations were due to the misinterpretation of anterior ST-segment elevation and this finding was commonly seen in African-Americans with left ventricular hypertrophy.

Association between prehospital electrocardiogram use and patient home distance from the percutaneous coronary intervention center on total reperfusion time in ST-segment-elevation myocardial infarction patients: a retrospective analysis from the national cardiovascular data registry

BACKGROUND

Current guidelines recommend ≤90 minutes from first medical contact to percutaneous coronary intervention (FMC2B) for ST-segment-elevation myocardial infarction (STEMI) patients. We evaluated the relationship between patient home distance from a percutaneous coronary intervention (PCI) center, prehospital electrocardiogram (ECG) use, and FMC2B time among patients with STEMI.

METHODS

We performed a retrospective cohort study including all STEMI patients in the ACTION-Get With The Guidelines registry from July 1, 2008, to September 30, 2012, who were transported by ambulance to a PCI center. Patient home distance was defined as the driving distance from the patient's home zip code to the PCI center address. Distance was classified into tertiles, and linear regression was used to characterize the interaction between prehospital ECG use and patient home distance with respect to FMC2B time.

RESULTS

Of the 29,506 STEMI patients, 19,690 (67%) received a prehospital ECG. The median patient home distance to the PCI center was 11.0 miles among patients with and 9.9 miles among those without a prehospital ECG. Prehospital ECGs were associated with a 10-minute reduction in the FMC2B time (P < .0001), which was consistent across distance tertiles (11 vs 11 vs 10 minutes). The association between prehospital ECGs and shorter FMC2B was attenuated by 0.8 minute for every 10-mile increase in distance (interaction P = .0002).

CONCLUSIONS

Prehospital ECGs are associated with a 10-minute reduction in the FMC2B time. However, patient home distance from a PCI center does not substantially change this association.

Evaluation and management of the atrial fibrillation patient: a report from the Society of Cardiovascular Patient Care

Atrial fibrillation (AF) is the most common cardiac dysrhythmia, and its prevalence is growing. The care of patients with AF is complex and involves multiple specialties and venues of care. Guideline recommendations are available for AF therapy; however, their implementation can be challenging. The Society of Cardiovascular Patient Care has developed an accreditation program, formulated by an expert committee on AF. Accreditation is based on specific criteria in 7 domains: (1) community outreach, (2) prehospital care, (3) early stabilization, (4) acute care, (5) transitions of care, (6) clinical quality measures, and (7) governance. This document presents the rationale, discussion, and supporting evidence for these criteria, in an effort to maximize effective and efficient AF care.

Long-term outcomes of patients sent emergently to the catheterization laboratory for possible primary percutaneous coronary intervention

Current guidelines advocate primary percutaneous coronary intervention as the therapy of choice for ST-segment elevation myocardial infarction (STEMI) when available. Little is known about the outcomes of patients without a culprit lesion after referral for primary percutaneous coronary intervention for a presumed STEMI. Subjects were identified within a registry containing consecutive patients who underwent emergent angiography for a potential STEMI from October 2008 to July 2012. Vital status was obtained from the medical record and Social Security Death Index. Cox proportional hazards models were created to evaluate the relation between the angiographic findings and cardiovascular outcomes, including major adverse cardiovascular events (MACE) and mortality. Among 539 patients who underwent emergent angiography, 65 (12%) had no coronary artery disease (CAD), 110 (20%) had CAD without a culprit lesion, and 364 (68%) had a culprit lesion. Kaplan-Meier analysis of MACE demonstrated that patients with CAD who lack a culprit lesion had a similar rate of MACE to those with a culprit lesion (p = 0.64), and both groups had significantly increased risk compared with those with no CAD (hazard ratio [HR] 1.9, 95% confidence interval [CI] 1.01 to 3.41 and HR 2.0, 95% CI 1.15 to 3.54, respectively). Kaplan-Meier analysis of mortality illustrated a nonsignificant trend toward increased mortality in patients having a culprit lesion (HR 1.7, 95% CI 0.59 to 4.80) and those having CAD without a culprit lesion (HR 1.2, 95% CI 0.39 to 3.81) compared with those with no CAD. In conclusion, patients found to have CAD without a culprit lesion in emergent angiography after a presumptive STEMI diagnosis have similar long-term rates of MACE compared with those requiring emergent revascularization.

Physician accuracy in interpreting potential ST-segment elevation myocardial infarction electrocardiograms

Background

With adoption of telemedicine, physicians are increasingly asked to diagnose ST‐segment elevation myocardial infarctions (STEMIs) based on electrocardiograms (ECGs) with minimal associated clinical information. We sought to determine physicians' diagnostic agreement and accuracy when interpreting potential STEMI ECGs.

Methods and Results

A cross‐sectional survey was performed consisting of 36 deidentified ECGs that had previously resulted in putative STEMI diagnoses. Emergency physicians, cardiologists, and interventional cardiologists participated in the survey. For each ECG, physicians were asked, “based on the ECG above, is there a blocked coronary artery present causing a STEMI?” The reference standard for ascertaining the STEMI diagnosis was subsequent emergent coronary arteriography. Responses were analyzed with generalized estimating equations to account for nested and repeated measures. One hundred twenty‐four physicians interpreted a total of 4392 ECGs. Among all physicians, interreader agreement (kappa) for ECG interpretation was 0.33, reflecting poor agreement. The sensitivity to identify “true” STEMIs was 65% (95% CI: 63 to 67) and the specificity was 79% (95% CI: 77 to 81). There was a 6% increase in the odds of accurate ECG interpretation for every 5 years of experience since medical school graduation (OR 1.06, 95% CI: 1.02 to 1.10, P=0.01). After adjusting for experience, there was no significant difference in the odds of accurate interpretation by specialty—Emergency Medicine (reference), General Cardiology (AOR 0.97, 95% CI: 0.79 to 1.2, P=0.80), or Interventional Cardiology physicians (AOR 1.24, 95% CI: 0.93 to 1.7, P=0.15).

Conclusions

There is significant physician disagreement in interpreting ECGs with features concerning for STEMI. Such ECGs lack the necessary sensitivity and specificity to act as a suitable “stand‐alone” diagnostic test.

Positive predictive value of clinically suspected ST-segment elevation myocardial infarction using angiographic verification

Fibrinolysis has not been used for the treatment of ST-segment elevation myocardial infarction (STEMI) in Denmark since 2005. We aimed to assess the positive predictive value of clinically suspected STEMI among consecutive patients in a real-world setting where all patients with suspected STEMI undergo acute coronary angiography. We evaluated the clinical diagnosis of consecutive patients with suspected STEMI admitted to Aarhus University Hospital between September 1, 2010, and August 31, 2011. Conclusive STEMI was defined as a patient with an identifiable culprit lesion by angiography. Of 615 patients with suspected STEMI, 483 (79%) had conclusive STEMI, and 132 (21%) did not have an identifiable culprit lesion. A higher proportion of patients with conclusive STEMI were men, whereas patients without conclusive STEMI were more likely to have diabetes mellitus (16% vs 10%; p = 0.04), left bundle branch block (24% vs 2%; p <0.001), hypertension (48% vs 36%; p = 0.01), or a history of coronary artery bypass surgery (8% vs 2%; p = 0.001). Compared with the overall 79% with conclusive STEMI, patients with left bundle branch block or a history of coronary artery bypass surgery had positive predictive values of only 26% and 41%, respectively. Our findings thus indicate that a substantial number of patients would have received fibrinolysis, without any potential benefit but with the inherent risk of bleeding complications, if acute angiography had not been an option.