Characteristics and outcomes of out-of-hospital sudden cardiac arrest according to the time of occurrence.

PURPOSE: The impact of time of occurrence has been extensively evaluated for in-hospital cardiac arrests but less for Out-of-Hospital Cardiac Arrests (OHCA). We assessed the impact of the time of occurrence on the characteristics and prognosis of OHCA.

METHODS: Using data from the Paris Sudden Cardiac Death Expertise Center prospective study that includes all OHCA in the Paris Area, we compared characteristics and outcomes of off-hours OHCA (nights and days off) to regular-hours OHCA between 2011 and 2014.

RESULTS: Among a total of 9834 OHCA (70.0±17years old, 62.1% males), off-hours OHCA accounted for 63.4%. Although bystanders were more often present (74.4 vs. 72.1%, P=0.01), rates of bystander CPR (46.7 vs. 50.6%, P=0.001) and AED use (1.0 vs. 1.9%, P=0.01) were lower during off-hours. While EMS arrival delays were similar, patients were less often in shockable rhythm (16.3 vs. 19.1%, P<0.0001), and return of spontaneous circulation was less frequent (27.5 vs. 31.1%, P<0.0001). There was no difference in rates of targeted temperature control (54.8 vs. 54.7%, P=0.75), coronary angiography (57.3 vs. 58.2%, P=0.68) and angioplasty use (32.2 vs. 35.6%, P=0.22). Survival at hospital discharge was lower (4.7 vs. 6.5%, P<0.0001) during off-hours. After adjusting for potential confounders, time of occurrence was not associated with worse outcome (OR 0.85, 95% CI 0.69-1.06, P=0.15), and bystander-initiated CPR, shockable initial rhythm and AED use were the main survival predictors (P<0.0001).

CONCLUSION: Off-hours OHCA have a 30% lower survival rate, mainly due to differences in initial management (bystander CPR and AED use), illustrating the need to improve bystanders' responsiveness in all circumstances.