Ground Emergency Medical Services Requests for Helicopter Transfer of ST-segment Elevation Myocardial Infarction Patients Decrease Medical Contact to Balloon Times in Rural and Suburban Settings

Objectives: ST-segment elevation myocardial infarction (STEMI) care is time-dependent. Many STEMI patients require interhospital helicopter transfer for percutaneous coronary intervention (PCI) if ground emergency medical services (EMS) initially transport the patient to a non-PCI center. This investigation models potential time savings of ground EMS requests for helicopter EMS (HEMS) transport of a STEMI patient directly to a PCI center, rather than usual transport to a local hospital with subsequent transfer. Methods: Data from a multicenter retrospective chart review of STEMI patients transferred for primary PCI by a single HEMS agency over 12 months were used to model medical contact to balloon times (MCTB) for two scenarios: a direct-to-scene HEMS response and hospital rendezvous after ground EMS initiation of transfer. Results: Actual MCTB median time for 36 hospital-initiated transfers was 160 minutes (range = 116 to 321 minutes). Scene response MCTB median time was estimated as 112 minutes (range = 69 to 187 minutes). The difference in medians was 48 minutes (95% confidence interval [CI] = 33 to 62 minutes). Hospital rendezvous MCTB median time was estimated as 113 minutes (range = 74 to 187 minutes). The difference in medians was 47 minutes (95% CI = 32 to 62 minutes). No patient had an actual MCTB time of less than 90 minutes; in the scene response and hospital rendezvous scenarios, 2 of 36 (6%) and 3 of 36 (8%), respectively, would have had MCTB times under 90 minutes. Conclusions: In this setting, ground EMS initiation of HEMS transfers for STEMI patients has the potential to reduce MCTB time, but most patients will still not achieve MCTB time of less than 90 minutes.