(HealthDay News) — Using an ambulance for hospital transport of patients with ST-segment elevation myocardial infarction (MI) is associated with higher mortality, according to a study published in the November 1 issue of The American Journal of Cardiology.

Lucy J. Boothroyd, PhD, from Institut national d’excellence en santé et en services sociaux in Montreal, and colleagues conducted a six-month evaluation (2008–2009) of all 82 acute care hospitals in the Canadian province of Quebec that treated at least 30 acute MIs annually. Data from medical records and administrative databases were extracted and analyzed.

The researchers found that, of the 1,956 patients, 62.5% arrived by ambulance. Ambulance users were older; more often women; and more likely to have comorbidities, low systolic pressure, abnormal heart rate, and a higher Thrombolysis In Myocardial Infarction risk index at presentation. Receipt of fibrinolysis and primary angioplasty were less likely for ambulance users (78.5 vs. 83.2% for nonusers; P=0.01), although if they did receive them, treatment delays were shorter (P<0.001). For ambulance users, the one-year mortality rate was 18.7%, compared to 7.1% for nonusers (P<0.001). This mortality difference persisted after adjusting for presenting risk factors, comorbidities, reperfusion treatment, and symptom duration (hazard ratio, 1.56).

“Mortality of [ambulance] users was substantially greater after adjustment for clinical risk factors, although they received faster reperfusion treatment overall,” the authors write.

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