The effect of interhospital transfers, emergency medical services, and distance on ischemic time in a rural ST-elevation myocardial infarction system of care.

Background: Regional myocardial infarction systems of care have been shown to improve timely access to primary percutaneous coronary intervention (PCI). However, there is a relatively sparse research on rural "frontier" regions. Arrival mode, high rates of interhospital transfers, long transport times, low population density, and mostly volunteer emergency medical services (EMS) distinguish this region from metropolitan systems of care. We sought to assess the effect of interhospital transfers, distance, and arrival mode on total ischemic times for patients with ST-elevation myocardial infarctions undergoing primary PCI.

Methods: We assessed patient data from our observational cohort of 395 patients with ST-elevation myocardial infarction with PCI as their primary treatment strategy. Data came from the 10 PCI hospitals participating in the Wyoming Mission: Lifeline program from January 2013 to September 2014. We performed both regression and tests of differences.

Results: Median total ischemic time was nearly 2.7 times greater in transferred patients than those presenting directly (379 vs 140 minutes). Distance in miles traveled between patient's home and PCI facility was 2.5 times larger in transfer patients (51 vs 20 miles). Emergency medical services arrival was associated with 23% shorter total ischemic times than self-arrival.

Conclusions: Transfer patients from referral hospitals had significantly greater total ischemic time, and use of EMS was associated with significantly lower times. Transport distance was mixed in its effect. These findings suggest a continued focus on improving transitions between referral and receiving centers and enhancing coordination in rural systems of care to reduce the multiplier effect of transfers on total ischemic time.