A comparison of door-to-balloon times and false-positive activations between emergency department and out-of-hospital activation of the coronary catheterization team

Artificial Intelligence Driven Prehospital ECG Interpretation for the Reduction of False Positive Emergent Cardiac Catheterization Lab Activations: A Retrospective Cohort Study

OBJECTIVES

Data suggest patients suffering acute coronary occlusion myocardial infarction (OMI) benefit from prompt primary percutaneous intervention (PPCI). Many emergency medical services (EMS) activate catheterization labs to reduce time to PPCI, but suffer a high burden of inappropriate activations. Artificial intelligence (AI) algorithms show promise to improve electrocardiogram (ECG) interpretation. The primary objective was to evaluate the potential of AI to reduce false positive activations without missing OMI.

METHODS

Electrocardiograms were categorized by (1) STEMI criteria, (2) ECG integrated device software and (3) a proprietary AI algorithm (Queen of Hearts (QOH), Powerful Medical). If multiple ECGs were obtained and any one tracing was positive for a given method, that diagnostic method was considered positive. The primary outcome was OMI defined as an angiographic culprit lesion with either TIMI 0-2 flow; or TIMI 3 flow with either peak high sensitivity troponin-I > 5000 ng/L or new wall motion abnormality. The primary analysis was per-patient proportion of false positives.

RESULTS

A total of 140 patients were screened and 117 met criteria. Of these, 48 met the primary outcome criteria of OMI. There were 80 positives by STEMI criteria, 88 by device algorithm, and 77 by AI software. All approaches reduced false positives, 27% for STEMI, 22% for device software, and 34% for AI (p < 0.01 for all). The reduction in false positives did not significantly differ between STEMI criteria and AI software (p = 0.19) but STEMI criteria missed 6 (5%) OMIs, while AI missed none (p = 0.01).

CONCLUSIONS

In this single-center retrospective study, an AI-driven algorithm reduced false positive diagnoses of OMI compared to EMS clinician gestalt. Compared to AI (which missed no OMI), STEMI criteria also reduced false positives but missed 6 true OMI. External validation of these findings in prospective cohorts is indicated.

Utility of prehospital electrocardiogram interpretation in ST-segment elevation myocardial infarction utilizing computer interpretation and transmission for interventional cardiologist consultation

Objectives

We examined the appropriateness of prehospital cardiac catheter laboratory activation (CCL‐A) in ST‐segment elevation myocardial infarction (STEMI) utilizing the University of Glasgow algorithm (UGA) and remote interventional cardiologist consultation.

Background

The incremental benefit of prehospital electrocardiogram (PH‐ECG) transmission on the diagnostic accuracy and appropriateness of CCL‐A has been examined in a small number of studies with conflicting results.

Methods

We identified consecutive PH‐ECG transmissions between June 2, 2010 and October 6, 2016. Blinded adjudication of ECGs, appropriateness of CCL‐A, and index diagnoses were performed using the fourth universal definition of MI. The primary outcome was the appropriate CCL‐A rate. Secondary outcomes included rates of false‐positive CCL‐A, inappropriate CCL‐A, and inappropriate CCL nonactivation.

Results

Among 1088 PH‐ECG transmissions, there were 565 (52%) CCL‐As and 523 (48%) CCL nonactivations. The appropriate CCL‐A rate was 97% (550 of 565 CCL‐As), of which 4.9% (n = 27) were false‐positive. The inappropriate CCL‐A rate was 2.7% (15 of 565 CCL‐As) and the inappropriate CCL nonactivation rate was 3.6% (19 of 523 CCL nonactivations). Reasons for appropriate CCL nonactivation (n = 504) included nondiagnostic ST‐segment elevation (n = 128, 25%), bundle branch block (n = 132, 26%), repolarization abnormality (n = 61, 12%), artefact (n = 72, 14%), no ischemic symptoms (n = 32, 6.3%), severe comorbidities (n = 26, 5.2%), transient ST‐segment elevation (n = 20, 4.0%), and others.

Conclusions

PH‐ECG interpretation utilizing UGA with interventional cardiologist consultation accurately identified STEMI with low rates of inappropriate and false‐positive CCL‐As, whereas using UGA alone would have almost doubled CCL‐As. The benefits of cardiologist consultation were identifying “masquerading” STEMI and avoiding unnecessary CCL‐As.

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.

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.

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.

Improving Electrocardiography Diagnostic Accuracy in Emergency Medical Services Personnel

Background

Accuracy of electrocardiogram (ECG) interpretation is important for identification of ST-elevation myocardial infarction (STEMI) by Emergency Medical Services (EMS) personnel who recognize STEMI in the field and activate the coronary catheterization laboratory. According to previous research, there is improvement in diagnosis of STEMIs for healthcare providers who read an average of > 20 ECGs per week. This study evaluated the effectiveness of online ECG modules on improving diagnostic accuracy.

Methods

EMS personnel received 25 ECGs per week to interpret via an online program. Diagnostic accuracy was assessed for improvement via completion of an ECG evaluation package before and after the intervention. Job satisfaction data were collected to determine the impact of the educational initiative.

Results

A total of 64 participants completed the study. Overall, there was an improvement in ECG diagnostic accuracy from 50.8% to 61.2% (95% confidence interval [CI], 7.7-13.2; P < 0.0001). Specifically, there was significant improvement in the diagnosis of STEMI (8.5%; 95% CI, 4.9-12.3; P < 0.003) and supraventricular tachycardia (39.0%; 95% CI, 17.2-60.8; P < 0.008), with a trend toward improvement in all other diagnoses. These effects were sustained to 3 months (9.6%; 95% CI, 6.4-12.7; P < 0.0001). Improvement was seen regardless of employment experience and training. There was no significant impact on job satisfaction.

Conclusions

ECG exposure remains an important factor in improving the accuracy of ECG diagnosis in EMS personnel. Online education modules provide an easily accessible way of improving ECG interpretation with the opportunity for positive downstream effects on patient outcomes and resource use.

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.

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.

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.

Computerized interpretation of the prehospital electrocardiogram: predictive value for ST segment elevation myocardial infarction and impact on on-scene time

Introduction:

Computerized interpretation of the prehospital electrocardiogram (ECG) is increasingly being used in the basic life support (BLS) ambulance setting to reduce delays to treatment for patients suspected of ST segment elevation myocardial infarction (STEMI).

Objectives:

To estimate 1) predictive values of computerized prehospital 12-lead ECG interpretation for STEMI and 2) additional on-scene time for 12-lead ECG acquisition.

Methods:

Over a 2-year period, 1,247 ECGs acquired by primary care paramedics for suspected STEMI were collected. ECGs were interpreted in real time by the GEMarquette 12SL ECG analysis program. Predictive values were estimated with a bayesian latent class model incorporating the computerized ECG interpretations, consensus ECG interpretations by study cardiologists, and hospital diagnosis. On-scene time was compared for ambulance-transported patients with (n 5 985) and without (n 5 5,056) prehospital ECGs who received prehospital aspirin and/or nitroglycerin.

Results:

The computer's positive and negative predictive values for STEMI were 74.0% (95% credible interval [CrI] 69.6–75.6) and 98.1% (95% CrI 97.8–98.4), respectively. The sensitivity and specificity were 69.2% (95% CrI 59.0–78.5) and 98.9% (95% CrI 98.1–99.4), respectively. Prehospital ECGs were associated with a mean increase in on-scene time of 5.9 minutes (95% confidence interval 5.5–6.3).

Conclusions:

The predictive values of the computerized prehospital ECG interpretation appear to be adequate for diversion programs that direct patients with a positive result to hospitals with angioplasty facilities. The estimated 26.0% chance that a positive interpretation is false is likely too high for activation of a catheterization laboratory from the field. Acquiring prehospital ECGs does not substantially increase on-scene time in the BLS setting.

Diagnostic accuracy of ST-segment elevation myocardial infarction by various healthcare providers

BACKGROUND

This study aimed to compare the accuracy of ECG interpretation for diagnosis of STEMI by different groups of healthcare professionals involved in the STEMI program at our institution.

METHODS

We selected 21 ECGs from patients with typical symptoms of MI that were diagnosed with STEMI, and 10 ECGs of STEMI mimics. STEMI mimic ECGs were repeated in the package with a story of typical and atypical chest pain. ECGs were interpreted to diagnose STEMI and identify need for initiation of the cardiac catheterization lab (CCL). Participants identified confidence in STEMI recognition, and average number of ECGs read per week.

RESULTS

A total of 64 participants completed the study package. Cardiologists were more likely to provide correct interpretation compared to other groups. False positive diagnoses were more likely made by paramedics when compared to cardiologists (p < 0.01). There was a positive correlation between increased exposure to ECGs and accurate STEMI diagnosis (r = 0.482, p < 0.001). A threshold of ≥ 20 ECGs read per week showed a statistically significant improvement in accuracy (p < 0.001). Self-reported confidence correlated positively with accuracy (r = 0.402, p =< 0.001). Changing the ECG narrative of the STEMI mimic ECGs had a significant effect on interpretation between groups (p = 0.043).

CONCLUSIONS

Our study showed that healthcare profession and number of ECGs reviewed per week are predictive of the accuracy of ECG interpretation of STEMI. Cardiologists are the most accurate diagnosticians, and are the least likely to falsely activate the CCL. Weekly exposure of ≥ 20 ECGs may improve diagnostic accuracy regardless of underlying experience.

Early text page alarms sent to cardiologists reduce door-to-balloon times in ST-elevation myocardial infarction

We assessed an early notification system using smartphones to reduce door-to-balloon times (DTBT) in ST-elevation myocardial infarction (STEMI). Text page alarms were sent to cardiologists for all patients presenting with chest pain or an equivalent in the emergency department before acquisition of an electrocardiogram (ECG). A total of 210 patients (with mean age of 59 years) were investigated (109 in the intervention group and 101 in a control group from the previous two-year period). The primary outcome, the DTBT, was significantly lower in the intervention group compared to the control group (55.0 and 92.5 min, respectively, P < 0.001). In a secondary analysis, the length of hospital stay was also significantly less. However, there was no significant improvement in all-cause one-year mortality. Early text page alarms using smartphones were effective in reducing the DTBT, but had a limited effect on clinical outcome.

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.

Cellular technology improves transmission success of pre-hospital electrocardiograms

STUDY OBJECTIVE

In rural settings, long distances and transport times pose a challenge for achieving early reperfusion goals in patients with ST-elevation myocardial infarction (STEMI). This study investigated the association between the method of pre-hospital 12-lead ECG transmission (radio transmission vs. cellular phone transmission) and the success of transmission and legibility of 12-lead ECGs in a rural setting.

METHODS

Observational study of pre-hospital 12-lead ECG transmission to the emergency department (ED) in a predominantly rural area. Success of transmission and the legibility of the 12-lead ECG were analyzed to identify barriers to 12-lead ECG transmission and reasons for failed transmission.

RESULTS

Emergency medical services performed ECGs on 1140 patients, 917 of which they attempted to transmit, including 43 cases requiring emergent catheterization. Twelve-lead ECG transmission was successful in 236 (70%) of 337 radio attempts and 441 (76%) of 580 cellular attempts (difference 6.0%, 95% CI 1.1-12.1). Legibility increased from 164 (49%) of 337 radio attempts to 389 (67%) of 580 cellular attempts (difference 18.4%, 95% CI 11.8-24.9).

CONCLUSION

The success of transmission and legibility of 12-lead ECGs was significantly higher with cellular technology by emergency medical service agencies in comparison to radio transmission. In rural settings with lengthy transport times, utilization of cellular technology for transmission of pre-hospital 12-lead ECGs may improve door-to-balloon times for STEMI patients.

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

Background—

For patients with an acute ST-segment elevation myocardial infarction, cardiac catheterization laboratory (CCL) activation by emergency medical technicians or emergency physicians has been shown to substantially reduce treatment times. One drawback to this approach involves overtriage, whereby CCL staffs are activated for patients who ultimately do not require emergent coronary angiography or for patients who undergo angiography but are not found to have coronary artery occlusion.

Methods and Results—

We examined CCL activation at 14 primary angioplasty hospitals to determine the course of management, including the rate of inappropriate activation. Among 3973 activations (29% by emergency medical technicians, 71% by emergency physicians) between December 2008 and December 2009, appropriate CCL activations occurred for 3377 patients (85%), with 2598 patients (76.9% of appropriate activations) receiving primary percutaneous coronary intervention. Reasons for inappropriate activations (596 patients; 15%) included ECG reinterpretations (427 patients; 72%) or the fact that the patient was not a CCL candidate (169 patients; 28%). The rate of cancellation because of reinterpretation of emergency medical technicians' ECG (6% of all activations) was more common than for cancellation because of reinterpretation of emergency physicians' ECG (4.6%).

Conclusions—

This represents the first report of the rates of CCL cancellation for ST-segment elevation myocardial infarction system activation by emergency medical technicians and emergency physicians in a large group of hospitals organized within a statewide program. The high rate of coronary intervention and relatively low rate of inappropriate activation suggest that systematic CCL activation by emergency personnel on a broad scale is feasible and accurate, and these rates set a benchmark for ST-segment elevation myocardial infarction systems.

The efficacy and value of emergency medicine: a supportive literature review

Study objectives

The goal of this study was to identify publications in the medical literature that support the efficacy or value of Emergency Medicine (EM) as a medical specialty and of clinical care delivered by trained emergency physicians. In this study we use the term "value" to refer both to the "efficacy of clinical care" in terms of achieving desired patient outcomes, as well as "efficiency" in terms of effective and/or cost-effective utilization of healthcare resources in delivering emergency care. A comprehensive listing of publications describing the efficacy or value of EM has not been previously published. It is anticipated that the accumulated reference list generated by this study will serve to help promote awareness of the value of EM as a medical specialty, and acceptance and development of the specialty of EM in countries where EM is new or not yet fully established.

Methods

The January 1995 to October 2010 issues of selected journals, including the EM journals with the highest article impact factors, were reviewed to identify articles of studies or commentaries that evaluated efficacy, effectiveness, and/or value related to EM as a specialty or to clinical care delivered by EM practitioners. Articles were included if they found a positive or beneficial effect of EM or of EM physician-provided medical care. Additional articles that had been published prior to 1995 or in other non-EM journals already known to the authors were also included.

Results

A total of 282 articles were identified, and each was categorized into one of the following topics: efficacy of EM for critical care and procedures (31 articles), efficacy of EM for efficiency or cost of care (30 articles), efficacy of EM for public health or preventive medicine (34 articles), efficacy of EM for radiology (11 articles), efficacy of EM for trauma or airway management (27 articles), efficacy of EM for using ultrasound (56 articles), efficacy of EM faculty (34 articles), efficacy of EM residencies (24 articles), and overviews and editorials of EM efficacy and value (35 articles).

Conclusion

There is extensive medical literature that supports the efficacy and value for both EM as a medical specialty and for emergency patient care delivered by trained EM physicians.

The STAT-MI (ST-Segment Analysis Using Wireless Technology in Acute Myocardial Infarction) trial improves outcomes

OBJECTIVES

The goal of this study was to evaluate the impact of the STAT-MI (ST-Segment Analysis Using Wireless Technology in Acute Myocardial Infarction) network on outcomes in the treatment of patients presenting with ST-segment elevation myocardial infarction (STEMI).

BACKGROUND

Shortening door-to-balloon (D2B) time remains a national priority for the treatment of STEMI. We previously reported a fully automated wireless network (STAT-MI) for transmission of electrocardiograms (ECGs) for suspected STEMI from the field to offsite cardiologists, allowing early triage with shortening of subsequent D2B times. We now report the impact of the STAT-MI wireless network on infarct size, length of hospital stay (LOS), and mortality.

METHODS

A fully automated wireless network (STAT-MI) was developed to enable automatic 12-lead ECG transmission and direct communication between emergency medical services personnel and offsite cardiologists that facilitated direct triage of patients to the cardiac catheterization laboratory. Demographic, laboratory, and time interval data of STAT-MI network patients were prospectively collected over a 33-month period and compared with concurrent control patients who presented with STEMI through non-STAT-MI pathways.

RESULTS

From June 2006 through February 2009, 92 patients presented via the STAT-MI network, and 50 patients presented through non-STAT-MI pathways (control group). Baseline clinical and demographic variables were similar in both groups. Overall, compared with control subjects, STAT-MI patients had significantly shorter D2B times (63 [42 to 87] min vs. 119 [96 to 178] min, U = 779.5, p < 0.00004), significantly lower peak troponin I (39.5 [11 to 120.5] ng/ml vs. 87.6 [38.4 to 227] ng/ml, U = 889.5, p = 0.005) and creatine phosphokinase-MB (126.1 [37.2 to 280.5] ng/ml vs. 290.3 [102.4 to 484] ng/ml, U = 883, p = 0.001), higher left ventricular ejection fractions (50% [35 to 55] vs. 35% [25 to 52], U = 1,075, p = 0.004), and shorter LOS (3 [2 to 4] days vs. 5.5 [3.5 to 10.5] days, U = 378, p < 0.001).

CONCLUSIONS

A fully automated, field-based, wireless network that transmits ECGs automatically to offsite cardiologists for the early evaluation and triage of patients with STEMI shortens D2B times, reduces infarct size, limits ejection fraction reduction, and shortens LOS.

Effect of emergency department in-hospital tele-electrocardiographic triage and interventional cardiologist activation of the infarct team on door-to-balloon times in ST-segment-elevation acute myocardial infarction

Current guidelines recommend that >75% of patients with ST-elevation myocardial infarction (STEMI) receive primary percutaneous coronary intervention (PPCI) within 90 minutes. The goal has been hardly achievable, so we conducted a 2-year before-and-after study to determine the impact of emergency department (ED) tele-electrocardiographic (tele-ECG) triage and interventional cardiologist activation of the infarct team at door-to-balloon time (D2BT) and the proportion of patients undergoing PPCI within 90 minutes since arrival. In total 105 consecutive patients with acute STEMI (mean age 62 ± 13 years, 82% men) were studied, 54 before and 51 after the change in protocol. The 51patients in the tele-ECG group underwent tele-electrocardiography at the ED and electrocardiograms were transmitted to a third-generation mobile telephone of an on-call interventional cardiologist within 10 minutes of ED arrival. The infarct team was activated and PPCI was performed by the interventional cardiologist. Fifty-four patients with acute STEMI who underwent PPCI in the year before implementation of tele-electrocardiography served as control subjects. Median D2BT of the tele-ECG group was 86 minutes, significantly shorter than the median time of 125 minutes of the control group (p <0.0001). The proportion of patients who achieved a D2BT <90 minutes increased from 44% in the control group to 76% in the tele-ECG group (p = 0.0001). In conclusion, implementation of ED tele-ECG triage and interventional cardiologist activation of the infarct team can significantly shorten D2BT and result in a larger proportion of patients achieving guideline recommendations.

Hospital-based strategies contributing to percutaneous coronary intervention time reduction in the patient with ST-segment elevation myocardiaI infarction: a review of the "system-of-care" approach

A myriad of hospital-wide initiatives have been implemented with the goal of decreasing door-to-balloon time. Much of the evidence behind the common strategies used is unknown; multiple strategies have been suggested in the reduction to the use of this important time-sensitive intervention. Among 8 primary strategies, 2 have substantial evidence to support their implementation in the attempt to reduce door-to-balloon time in ST-segment elevation myocardial infarction (STEMI), including emergency physician activation of the cardiac catheterization laboratory and prehospital activation of the STEMI alert process. Two strategies have moderate evidence to support their use, including real-time data feedback to team members and team-based approach to STEMI management. The remaining 4 strategies have no quantitative evidence to support their use, including single call to a central paging system, expecting the cardiac catheterization laboratory personnel to arrive within 20 minutes of activation, attending cardiologist on site (within the hospital), and senior management commitment to the project. Although all the STEMI systems of care reviewed are associated with a decreased in time to treatment, only a few have sufficient quantitative evidence to support their implementation. To be effective, the movement to decrease time to treatment of STEMI at any hospital must be composed of an institutional response that includes multiple disciplines. Success also requires active participation from nurses, members of the catheterization team, and hospital leadership.

Automated electrocardiogram interpretation programs versus cardiologists' triage decision making based on teletransmitted data in patients with suspected acute coronary syndrome

The aims of this study were to assess the effectiveness of 2 automated electrocardiogram interpretation programs in patients with suspected acute coronary syndrome transported to hospital by ambulance in 1 rural region of Denmark with hospital discharge diagnosis used as the gold standard and to assess the effectiveness of cardiologists' triage decisions for these patients based on initial electrocardiogram. Twelve-lead electrocardiograms were recorded in ambulances using a LIFEPAK 12 monitor/defibrillator (Physio-Control, Inc., Redmond, Washington) and transmitted digitally to an attending cardiologist. If a diagnosis of ST elevation myocardial infarction was made, a patient was taken to a regional interventional center for primary percutaneous coronary intervention or to a local hospital. One thousand consecutive digital electrocardiograms and corresponding interpretations from LIFEPAK 12 were available, and these were subsequently interpreted by the University of Glasgow program. Electrocardiogram interpretations and cardiologists' decisions were compared to hospital discharge diagnoses. The sensitivity, specificity, and positive predictive values for a report of ST elevation myocardial infarction with respect to discharge diagnosis were 78%, 91%, and 81% for LIFEPAK 12 and 78%, 94%, and 87% for the Glasgow program. Corresponding data for attending cardiologists were 85%, 90%, and 81%. In conclusion, the Glasgow program had significantly higher specificity than the LIFEPAK 12 program (p = 0.02) and the cardiologists (p = 0.004). Triage decisions were effective, with good agreement between cardiologists' decisions and discharge diagnoses.