Introduction:
STEMI mortality decreased drastically during the last decades, and out-of-hospital sudden cardiac arrest (SCA) has become its main mode of death. The risk of out-of-hospital SCA according to the timing of STEMI occurrence has not been assessed. Hypothesis: The risk of SCA, prior to hospital admission, differs according to the timing of STEMI occurrence.
Methods:
Data were taken from a prospective pre-hospital study (e-MUST study) on all STEMI patients managed by emergency medical services in Paris and its suburbs between January 2006 and December 2010. In this area, emergency calls are routed to the closest dispatch center and regulated by physicians who send, in the field, an ambulance with a physician on board in case of suspected acute myocardial infarction. Pre-hospital EKGs are obtained for all patients and those presenting STEMI are included in the study. We assessed the rate of SCA, prior to hospital admission, according to the timing of STEMI occurrence (4 hours-time intervals starting at midnight).
Results:
Among the 8,112 STEMI patients enrolled (mean age (SD) 61.6 (14.3) years, 78% males), 452 patients (5.6%) developed out-of-hospital SCA. We observed significant circadian change in the rate of SCA per STEMI, with a progressive increase between 4am and 8pm, followed by a decrease between 8pm and 4am (P=0.0009). The peak rate of SCA per STEMI occurred in the 4pm-8pm time interval (7.7%), while the lowest rate was seen between 4am and 8am (4.2%) (Figure). Conclusions: The risk of STEMI-related SCA is almost 2-fold higher in STEMI occurring in the late afternoon hours. A better understanding of patients’ characteristics, circumstances of occurrence, and pre-hospital care is needed to eventually reduce the risk of SCA promptly after STEMI diagnosis in the field.