Prehospital management of acute myocardial infarct in an experimental metropolitan system of medical emergencies

BACKGROUND: Feasibility, safety and efficacy of prehospital management of acute myocardial infarction (AMI) and prehospital thrombolysis have been widely demonstrated. On this background, in March 1992 we started up an Emergency Medical Service (EMS)--Servizio per le Emergenze Cardiologiche Territoriali, SECT--aimed to prehospital care of overall cardiac emergencies (CE), including AMI. The Service, operating in the metropolitan area of Turin (130 Km2, 964,000 inhabitants), is based on a properly equipped ambulance, manned with a physician and a nurse, skilled in treatment of CE. METHODS: From March 1992 to December 1994, 5000 missions were performed, 2586 (51.7%) for chest pain, 1383 (53.5%) of presumed cardiac origin. Within the latter group, 426 (30.8%) cases of AMI, 109 (7.9%) cases of suspected AMI and 848 (61.3%) cases of angina were identified and treated. Decision time in AMI patients (pts) was 189.4 +/- 289.5 min (median 73), longer in pts over 70 years and in women. By means of a direct phone line between Emergency Communication System and metropolitan Coronary Care Units (CCU), 303/423 (71.6%) AMI pts, were directly admitted to CCU. Prehospital thrombolysis (PT) was performed in 211/426 pts (49.5%), with delay from symptom onset of 126.8 +/- 106.1 min (median 93). A rtPA "front loaded" regimen was used, with a full heparin and ASA as adjunctive therapy. Exclusion criteria for PT in 215 pts were: age > 75 years in 109 pts (50.7%), delay from symptom onset > 6 hrs in 55 (25.6%), ST depression in 33 (15.3%), contraindications to thrombolysis in 18 (8.4%). Eligibility to PT was 8.1% in chest pain pts and 43.5% in pts with AMI diagnosis at discharge. Another group of 38 pts underwent thrombolysis in hospital, after a review of inclusion criteria, with a longer delay of 231 +/- 184 min (median 150). RESULTS: Out-of-hospital diagnosis was confirmed in 91% of both AMI pts and PT pts, and in 56.7% of suspected AMI pts. Overall complication rate was 32.1%, with similar rates in PT treated pts and not PT treated pts. Prehospital mortality rate was 0.7%. In-hospital mortality rate was 5.2% in PT pts with confirmed AMI, and 16.2% in not PT pts with confirmed AMI. CONCLUSIONS: Our experience confirm efficacy of out-of-hospital management of AMI within an EMS designed to treat overall CE, considering successful treatment of complications and early thrombolysis with reduction of time delay. Inclusion of SECT in the growing up "118" Emergency Medical System raises logistic questions. Process will be completed when the "medical final authority" will submit each intervention to a full evaluation in terms of efficiency and efficacy, and will not only prepare, as now happens, dispatch and intervention protocols.