Safety and clinically important events in PCP-initiated STEMI bypass in Ottawa

The aim of this study was to determine what clinically important events occur in ST-elevation myocardial infarction (STEMI) patients transported for primary percutaneous coronary intervention (PCI) via a primary care paramedic (PCP) crew, and what proportion of such events could only be treated by advanced care paramedic (ACP) protocols.

We conducted a health record review of STEMI transports by PCP-only crews and those transferred from PCP to ACP crews (ACP-intercept) from 2011 to 2015. A piloted data collection form was used to extract clinically important events, interventions during transport, and mortality.

We identified 214 STEMI bypass cases (118 PCP-only and 96 ACP-intercept). Characteristics were mean age 61.4 years; 44.4% inferior infarcts; mean response time 6 minutes, 19 seconds; total paramedic contact time 29 minutes, 40 seconds; and, in cases of ACP-intercept, 7 minutes, 46 seconds of PCP-only contact time. A clinically important event occurred in 127 (59.3%) of cases: SBP < 90 mm Hg (26.2%), HR < 60 (30.4%), HR > 100 (20.6%), arrhythmias 7.5%, altered mental status 6.5%, airway intervention 2.3%. Two patients (0.9%) arrested, both survived. Of the events identified, 42.5% could be addressed differently by ACP protocols. The majority related to fluid boluses for hypotension (34.6%). In the ACP-intercept group, ACPs acted on 51.6% of events. There were six (2.8%) in-hospital deaths.

Although clinically important events are common in STEMI bypass patients, a smaller proportion of events would be addressed differently by ACP compared with PCP protocols. The majority of clinically important events were transient and of limited clinical significance. PCP-only crews can safely transport STEMI patients directly to primary PCI.