Identifying Patients at Risk for Prehospital Sudden Cardiac Arrest at the Early Phase of Myocardial Infarction

Background: In-hospital mortality of ST-segment–elevation myocardial infarction (STEMI) has decreased drastically. In contrast, prehospital mortality from sudden cardiac arrest (SCA) remains high and difficult to reduce. Identification of the patients with STEMI at higher risk for prehospital SCA could facilitate rapid triage and intervention in the field. Methods: Using a prospective, population-based study evaluating all patients with STEMI managed by emergency medical services in the greater Paris area (11.7 million inhabitants) between 2006 and 2010, we identified characteristics associated with an increased risk of prehospital SCA and used these variables to build an SCA prediction score, which we validated internally and externally. Results: In the overall STEMI population (n=8112; median age, 60 years; 78% male), SCA occurred in 452 patients (5.6%). In multivariate analysis, younger age, absence of obesity, absence of diabetes mellitus, shortness of breath, and a short delay between pain onset and call to emergency medical services were the main predictors of SCA. A score built from these variables predicted SCA, with the risk increasing 2-fold in patients with a score between 10 and 19, 4-fold in those with a score between 20 and 29, and >18-fold in patients with a score ≥30 compared with those with scores