Background: While advancements have been made in acute myocardial infarction (AMI) in the past decade, little is known about national trends in AMI care delivery in the ED. We used a nationally representative sample to describe trends in the epidemiology and quality of AMI care in the ED over a 10-year period.
Methods: This was a retrospective analysis of ED visits for AMI using the National Hospital Ambulatory Medical Care Survey, an annual survey of ED visits at ~500 US hospitals. AMI included ST-elevation myocardial infarction (STEMI) and non-ST elevation myocardial infarction (NSTEMI) defined by diagnostic codes. We used consensus-validated definitions that captured the full spectrum of AMI patients, including those with delayed ED diagnosis, those commonly excluded from quality measures, those with concomitant acute illness, and ED transfers. Data from 2005-2015 was grouped in 2-year increments and a final 3-year increment to ensure stability of estimates. Epidemiologic outcomes included the prevalence of AMI, STEMI, and NSTEMI. Quality outcomes included median ED length of visit (LOV), ED disposition type, and ED medication administration.
Results: The estimated prevalence of ED visits for AMI fell from 1,152,227 in 2005-2006 to 839,665 in 2012-2015. Over this period, the fraction of all AMI that were STEMI fell from 97% to 58%, while the fraction that were NSTEMI rose from 3% to 42%. Median LOV (inclusive of all ED length of stay until departure for procedure, hospitalization or transfer) fell from 190 to 145 minutes for STEMI and rose from 190 to 219 minutes for NSTEMI. The fraction of STEMI sent for catheterization rose from 11% to 40%. Transfer rates rose from 20% to 28% for STEMI and 7.5% to 12.0% for NSTEMI. ED administration of aspirin and non-aspirin antiplatelets rose for all AMI (15% to 46% and 9% to 17%, respectively). ED administration of antithrombotics rose for STEMI (24% to 33%) and fell for NSTEMI (33% to 24%).
Conclusion: Our data reflects real-world care processes for the entire spectrum of AMI patients in the ED. Based on these data, national trends in the epidemiology of ED care for AMI include decreasing AMI and STEMI prevalence and increasing NSTEMI diagnoses. National trends in ED care processes for AMI mirror evolving guidelines that favor high intensity antiplatelet therapy, early invasive strategies, and regionalization of care.