Causes of prehospital misinterpretations of ST elevation myocardial infarction

Objectives: To determine the causes of software misinterpretation of ST elevation myocardial infarction (STEMI) compared to clinically identified STEMI to identify opportunities to improve prehospital STEMI identification. Methods: We compared ECGs acquired from July 2011 through June 2012 using the LIFEPAK 15 on adult patients transported by the Los Angeles Fire Department. Cases included patients ≥18 years who received a prehospital ECG. Software interpretation of the ECG (STEMI or not) was compared with data in the regional EMS registry to classify the interpretation as true positive (TP), true negative (TN), false positive (FP), or false negative (FN). For cases where classification was not possible using registry data, 3 blinded cardiologists interpreted the ECG. Each discordance was subsequently reviewed to determine the likely cause of misclassification. The cardiologists independently reviewed a sample of these discordant ECGs and the causes of misclassification were updated in an iterative fashion. Results: Of 44,611 cases, 50% were male (median age 65; inter-quartile range 52–80). Cases were classified as 482 (1.1%) TP, 711 (1.6%) FP, 43371 (97.2%) TN, and 47 (0.11%) FN. Of the 711 classified as FP, 126 (18%) were considered appropriate for, though did not undergo, emergent coronary angiography, because the ECG showed definite (52 cases) or borderline (65 cases) ischemic ST elevation, a STEMI equivalent (5 cases) or ST-elevation due to vasospasm (4 cases). The sensitivity was 92.8% [95% CI 90.6, 94.7%] and the specificity 98.7% [95% CI 98.6, 98.8%]. The leading causes of FP were ECG artifact (20%), early repolarization (16%), probable pericarditis/myocarditis (13%), indeterminate (12%), left ventricular hypertrophy (8%), and right bundle branch block (5%). There were 18 additional reasons for FP interpretation (<4% each). The leading causes of FN were borderline ST-segment elevations less than the algorithm threshold (40%) and tall T waves reducing the ST/T ratio below threshold (15%). There were 11 additional reasons for FN interpretation occurring ≤3 times each. Conclusion: The leading causes of FP automated interpretation of STEMI were ECG artifact and non-ischemic causes of ST-segment elevation. FN were rare and were related to ST-segment elevation or ST/T ratio that did not meet the software algorithm threshold

The influence of left ventricular hypertrophyon survival in patients with coronaryartery disease: do race and gender matter?

AbstractObjectivesWe sought to determine the overall prognostic importance of left ventricular hypertrophy (LVH) among patients with coronary artery disease (CAD), as well as to determine whether this risk varies as a function of race or gender.BackgroundLeft ventricular hypertrophy is more prevalent among blacks and women than their counterparts. Blacks and women also have higher mortality with coronary disease.MethodsWe studied records of 2,461 patients (19% black, 42% women) diagnosed with CAD at cardiac catheterization between 1990 and 1998 from a single academic center. Left ventricular hypertrophy was defined using standard echocardiographic measures. Cox proportional hazards models were used for adjusted survival analyses. Mean patient follow-up was three years.ResultsPatients with LVH were older (68 vs. 65 years, p < 0.01), more often women (54% vs. 36%, p < 0.01), and black (25% vs. 16%, p < 0.01), and had higher unadjusted three-year mortality rates than patients without LVH (42% vs. 34%, p < 0.01). Left ventricular hypertrophy remained an independent predictor of mortality after adjusting for other clinical risk factors (hazard ratio 1.56, 95% confidence interval 1.35 to 1.80) with prognostic importance equivalent to that of left ventricular ejection fraction. Although the relative risk of LVH did not vary by race or gender, the attributable risk of LVH was greater in blacks and women.ConclusionsClinicians should consider the prognostic importance of LVH when assessing risk in patients with CAD. Because LVH is more common among black and women patients with CAD, it partially accounts for racial and gender differences in survival

Race differences in interventions and survival after Out-of-Hospital Cardiac Arrest in North Carolina, 2010 to 2014

Background Following the implementation of the HeartRescue project, with interventions in the community, emergency medical services, and hospitals to improve care and outcomes for out‐of‐hospital cardiac arrests (OHCA) in North Carolina, improved bystander and first responder treatments as well as survival were observed. This study aimed to determine whether these improvements were consistent across Black versus White individuals. Methods and Results Using the Cardiac Arrest Registry to Enhance Survival (CARES), we identified OHCA from 16 counties in North Carolina (population 3 million) from 2010 to 2014. Temporal changes in interventions and outcomes were assessed using multilevel multivariable logistic regression, adjusted for patient and socioeconomic neighborhood‐level factors. Of 7091 patients with OHCA, 36.5% were Black and 63.5% were White. Black patients were younger, more females, had more unwitnessed arrests and non‐shockable rhythm (Black: 81.0%; White: 75.4%). From 2010 to 2014, the adjusted probabilities of bystander cardiopulmonary resuscitation (CPR) went from 38.5% to 51.2% in White, P<0.001; and 36.9% to 45.6% in Black, P=0.002, and first‐responder defibrillation went from 13.2% to 17.2% in White, P=0.002; and 14.7% to 17.3% in Black, P=0.16. From 2010 to 2014, survival to discharge only increased in White (8.0% to 11.4%, P=0.004; Black 8.9% to 9.5%, P=0.60), though, in shockable patients the probability of survival to discharge went from 24.8% to 34.6% in White, P=0.02; and 21.7% to 29.0% in Black, P=0. 10. Conclusions After the HeartRescue program, bystander CPR and first‐responder defibrillation increased in both patient groups; however, survival only increased significantly for White patients

Impact of Regional Systems of Care on Disparities in Care Among Female and Black Patients Presenting With ST‐Segment–Elevation Myocardial Infarction

BACKGROUND: The American Heart Association Mission: Lifeline STEMI (ST-segment-elevation myocardial infarction) Systems Accelerator program, conducted in 16 regions across the United States to improve key care processes, resulted in more patients being treated within national guideline goals (time from first medical contact to device: <90 minutes for direct presenters to hospitals capable of performing percutaneous coronary intervention; <120 minutes for transfers). We examined whether the effort reduced reperfusion disparities in the proportions of female versus male and black versus white patients. METHODS AND RESULTS: In total, 23 809 patients (29.3% female, 82.3% white, and 10.7% black) presented with acute STEMI between July 2012 and March 2014. Change in the proportion of patients treated within guideline goals was compared between sex and race subgroups for patients presenting directly to hospitals capable of performing percutaneous coronary intervention (n=18 267) and patients requiring transfer (n=5542). The intervention was associated with an increase in the proportion of men treated within guideline goals that presented directly (58.7-62.1%, P=0.01) or were transferred (43.3-50.7%, P<0.01). An increase was also seen among white patients who presented directly (57.7-59.9%, P=0.02) or were transferred (43.9-48.8%, P<0.01). There was no change in the proportion of female or black patients treated within guideline goals, including both those presenting directly and transferred. CONCLUSION: The STEMI Systems Accelerator project was associated with an increase in the proportion of patients meeting guideline reperfusion targets for male and white patients but not for female or black patients. Efforts to organize systems of STEMI care should implement additional processes targeting barriers to timely reperfusion among female and black patients

Association of Rapid Care Process Implementation on Reperfusion Times Across Multiple ST-Segment–Elevation Myocardial Infarction Networks

BACKGROUND: The Mission: Lifeline STEMI Systems Accelerator program, implemented in 16 US metropolitan regions, resulted in more patients receiving timely reperfusion. We assessed whether implementing key care processes was associated with system performance improvement. METHODS AND RESULTS: Hospitals (n=167 with 23 498 ST-segment-elevation myocardial infarction patients) were surveyed before (March 2012) and after (July 2014) program intervention. Data were merged with patient-level clinical data over the same period. For reperfusion, hospitals were grouped by whether a specific process of care was implemented, preexisting, or never implemented. Uptake of 4 key care processes increased after intervention: prehospital catheterization laboratory activation (62%-91%; P<0.001), single call transfer protocol from an outside facility (45%-70%; P<0.001), and emergency department bypass for emergency medical services direct presenters (48%-59%; P=0.002) and transfers (56%-79%; P=0.001). There were significant differences in median first medical contact-to-device times among groups implementing prehospital activation (88 minutes implementers versus 89 minutes preexisting versus 98 minutes nonimplementers; P<0.001 for comparisons). Similarly, patients treated at hospitals implementing single call transfer protocols had shorter median first medical contact-to-device times (112 versus 128 versus 152 minutes; P<0.001). Emergency department bypass was also associated with shorter median first medical contact-to-device times for emergency medical services direct presenters (84 versus 88 versus 94 minutes; P<0.001) and transfers (123 versus 127 versus 167 minutes; P<0.001). CONCLUSIONS: The Accelerator program increased uptake of key care processes, which were associated with improved system performance. These findings support efforts to implement regional ST-segment-elevation myocardial infarction networks focused on prehospital catheterization laboratory activation, single call transfer protocols, and emergency department bypass

Regional Systems of Care Demonstration Project: American Heart Association Mission: Lifeline STEMI Systems Accelerator.

BACKGROUND: Up to 50% of patients fail to meet ST-segment-elevation myocardial infarction (STEMI) guideline goals recommending a first medical contact-to-device time of <90 minutes for patients directly presenting to percutaneous coronary intervention-capable hospitals and <120 minutes for transferred patients. We sought to increase the proportion of patients treated within guideline goals by organizing coordinated regional reperfusion plans. METHODS: We established leadership teams, coordinated protocols, and provided regular feedback for 484 hospitals and 1253 emergency medical services (EMS) agencies in 16 regions across the United States. RESULTS: Between July 2012 and December 2013, 23 809 patients presented with acute STEMI (direct to percutaneous coronary intervention hospital: 11 765 EMS transported and 6502 self-transported; 5542 transferred). EMS-transported patients differed from self-transported patients in symptom onset to first medical contact time (median, 47 versus 114 minutes), incidence of cardiac arrest (10% versus 3%), shock on admission (11% versus 3%), and in-hospital mortality (8% versus 3%; P<0.001 for all comparisons). There was a significant increase in the proportion of patients meeting guideline goals of first medical contact-to-device time, including those directly presenting via EMS (50% to 55%; P<0.001) and transferred patients (44%-48%; P=0.002). Despite regional variability, the greatest gains occurred among patients in the 5 most improved regions, increasing from 45% to 57% (direct EMS; P<0.001) and 38% to 50% (transfers; P<0.001). CONCLUSIONS: This Mission: Lifeline STEMI Systems Accelerator demonstration project represents the largest national effort to organize regional STEMI care. By focusing on first medical contact-to-device time, coordinated treatment protocols, and regional data collection and reporting, we were able to increase significantly the proportion of patients treated within guideline goals