Beneficial effects of direct call to emergency medical services in acute myocardial infarction.

Objectives: We investigated the impact of an emergency medical services call on the management of acute myocardial infarction, considering time intervals for intervention and revascularization procedures.

Methods: Data were prospectively collected from January 2001 to October 2002 from 531 patients hospitalized for myocardial infarction with ST segment elevation and a pre-hospital delay of less than 24 h.

Results: Only 26% of patients called the emergency medical services at the onset of symptoms (n=140). Other patients (n=391, 74%) called another medical contact. Baseline characteristics and cardiovascular history were similar in the two groups, except for the percutaneous coronary intervention history (10% in the emergency medical services group versus 4% in the other medical contact group, P<0.05). Time intervals from the onset of symptoms of myocardial infarction to call or to medical intervention, as well as the time interval from medical intervention to hospital admission were significantly shorter in the emergency medical services group. The early reperfusion rate was also significantly greater in the emergency medical services group (77%) compared with the other medical contact group (64%), mainly because of a greater incidence of primary percutaneous coronary intervention (36 versus 26%, P<0.03, respectively). Multivariate analysis adjusted for sex and age showed that less than three medical care providers [odds ratio (OR) 5.042, P<0.001], percutaneous coronary intervention history (OR 2.462, P<0.05), as well as rhythmic disorders (OR 2.105, P<0.05) and complete atrioventricular block (OR 2.757, P<0.05) were independent predictors of emergency medical services care.

Conclusion: This study demonstrated that a call to the emergency medical services is underutilized by patients with symptoms of myocardial infarction, and documented the beneficial effects of an emergency medical services call by reducing pre-hospital delays and increasing early revascularization therapies.