Objectives: To address the association between the 2003 heat wave in Paris (France) and the occurrence of out-of-hospital cardiac arrest.
Design: : An analysis of the interventions of the medical mobile intensive care units of the City of Paris for out-of-hospital cardiac arrest and prehospital myocardial infarctions, which were routinely and prospectively computerized from January 1, 2000, to December 31, 2005.
Setting: City of Paris, France.
Patients: Participants were consecutive victims of witnessed out-of-hospital cardiac arrest due to heart disease and of ST-segment elevation myocardial infarction (STEMI) aged >or=18 yrs, who were attended by the medical mobile intensive care units (MICUs) of the City of Paris from January 1, 2000, to December 31, 2005.
Measurements and main results: The numbers of out-of-hospital cardiac arrests and of STEMIs during the 2003 heat wave period (August 1 to August 14) were compared (Poisson regression analysis) with the respective average numbers during the same period in reference years 2000-2002 and 2004-2005 when there was no heat wave. Mean ages of the 3049 patients experiencing out-of-hospital cardiac arrest and the 2767 patients experiencing STEMI attended by the MICUs during the study period were 64.3 +/- 18.0 and 65.2 +/- 15.4, respectively, and two thirds were males. During the heat wave period, the number of out-of-hospital cardiac arrests (n = 40) increased 2.5-fold compared with the reference periods (n = 81 for 5 yrs; p < .001); this corresponded to an estimated relative rates of out-of-hospital cardiac arrests of 2.34 (95% confidence interval, 1.60-3.41), after adjustment for age and for gender. This increase was observed in both genders (p for interaction with gender = .48) but only in those who were aged >or=60 yrs (p for interaction with age = .005). No variation was found for myocardial infarctions during heat wave.
Conclusions: These data suggest that a heat wave may be associated with an increased risk of sudden cardiac death in the population.