Out-of-Hospital Cardiac Arrest in Southern Italy: A Retrospective Analysis of 11,653 Cases

(1) Background: Out-of-hospital cardiac arrest (OHCA) remains a major public health issue, with survival largely determined by the initial rhythm and timeliness of resuscitation. Comprehensive population-based data are essential for guiding prevention, emergency medical services (EMS) planning, and improving outcomes. (2) Methods: We performed a retrospective observational study of all adult OHCA cases managed by EMS in Lecce (Italy) between January 2013 and March 2025. Demographics, arrest circumstances, initial rhythm, time intervals, and return of spontaneous circulation (ROSC) were analyzed across age, sex, temporal, and pandemic-related strata. Rhythm classification followed European Resuscitation Council guidelines. (3) Results: A total of 11,653 cases were analyzed (mean age 76.8 ± 15.5 years, 56.6% male). Asystole (AS) was the predominant rhythm (88.7%), followed by ventricular fibrillation (VF, 7.6%), pulseless electrical activity (PEA, 1.3%), and pulseless ventricular tachycardia (pVT, 0.08%). VF was more common in younger and male patients, while AS increased with age. Hour-level analysis revealed circadian peaks: VF in late afternoon and AS in early morning. Pandemic analysis showed reduced VF and increased AS during COVID-19, with partial recovery post-pandemic. ROSC occurred in 3.47% overall, strongly associated with shockable rhythms. EMS response times were stable across day-night and pandemic phases. (4) Conclusions: AS dominates OHCA presentations, especially among the elderly, whereas VF remains the strongest predictor of ROSC. Circadian variation at the hourly level suggests potential for EMS optimization. Pandemic-related shifts in rhythm highlight the vulnerability of the chain of survival to societal disruptions. Strengthening bystander CPR, expanding AED availability, and tailoring EMS strategies remain key priorities for improving OHCA outcomes.