Direct paramedic transport of acute myocardial infarction patients to percutaneous coronary intervention centers: a decision analysis

Abstract

Study objective: One potential strategy in the emergency medical services (EMS) care of acute ST-segment elevation myocardial infarction (STEMI) is to bypass the nearest community hospital in favor of a more distant specialty center able to perform primary percutaneous coronary intervention. We seek to determine whether EMS transport of out-of-hospital STEMI patients directly to more distant specialty percutaneous coronary intervention centers will alter 30-day survival compared with transport to the nearest community hospital fibrinolytic therapy.

Methods: This decision analysis used parameter values and ranges from meta-analyses and North American clinical studies of STEMI and chest pain care published after 2001. The primary hypothetical interventions were primary percutaneous coronary intervention versus community hospital-delivered fibrinolytic therapy. We defined total STEMI treatment time as the sum of symptom duration, EMS response time, EMS scene time, EMS transport time to the nearest community hospital, additional EMS transport time to a more distant percutaneous coronary intervention center, and door-to-drug or door-to-balloon time. We related total STEMI treatment time to the primary outcome 30-day post-STEMI survival. We assumed that the closest specialty percutaneous coronary intervention centers were located farther than the nearest community hospital and that patients would receive primary percutaneous coronary intervention at specialty centers and fibrinolytic therapy at community hospitals. We assumed the use of ground transportation only and excluded situations with fibrinolytic therapy contraindications. We examined standard risk and best-case scenarios for each intervention, as well as changes in predicted risk with parameter value variations.

Results: Baseline total treatment times (chest pain onset to intervention) were percutaneous coronary intervention 188 minutes (range 41 to 447 minutes) and community hospital fibrinolytic therapy 118 minutes (range 51 to 267 minutes). Thirty-day survival was higher for standard percutaneous coronary intervention than standard community hospital fibrinolytic therapy (95.8% versus 93.8%; relative risk [RR] 1.021; number needed to treat 50) but lower when compared to best-case community hospital fibrinolytic therapy (95.8% versus 97.8%; RR 0.980; number needed to harm 50). Best-case percutaneous coronary intervention was equivalent to best-case community hospital fibrinolytic therapy (RR 1.000). In 1-way sensitivity analyses, best-case community hospital fibrinolytic therapy versus standard percutaneous coronary intervention was sensitive to treatment time parameter variations. Probabilistic sensitivity analysis favored standard percutaneous coronary intervention over standard community hospital fibrinolytic therapy (RR=1.020; 95% probability range 1.002 to 1.045) but did not indicate a favored strategy for the other scenarios.

Conclusion: In select out-of-hospital STEMI care scenarios, EMS transport of acute STEMI patients directly to percutaneous coronary intervention centers may offer small but uncertain survival benefits over nearest community hospital fibrinolytic therapy.