Epidemiology and outcomes of out of hospital cardiac arrest in Karachi, Pakistan - A longitudinal study.

Background: Out-of-hospital cardiac arrest (OHCA) is a major cause of morbidity and mortality globally, with survival outcomes remaining poor particularly in many low- and middle-income countries. We aimed to establish a pilot OHCA registry in Karachi, Pakistan to provide insights into OHCA patient demographics, pre-hospital and in-hospital care, and outcomes. Methods: A multicenter longitudinal study was conducted from August 2015-October 2019 across 11 Karachi hospitals, using a standardized Utstein-based survey form. Data was retrospectively obtained from medical records, patients, and next-of-kin interviews at hospitals with accessible medical records, while hospitals without medical records system used on-site data collectors. Demographics, arrest characteristics, prehospital events, and survival outcomes were collected. Survivors underwent follow-up at 1 month, 6 months, 1 year, and 5 years. Results: In total, 1068 OHCA patients were included. Mean age was 55 years, 61.1 % (n = 653) male. Witnessed arrests accounted for 94.9 % of the cases (n = 1013), whereas 89.4 % of the cases (n = 955) were transported via non-EMS. Bystander CPR was performed in 10.3 % (n = 110) cases whereas pre-hospital defibrillation performed in 0.4 % (n = 4). In-hospital defibrillation was performed in 9.9 % (n = 106) cases despite < 5 % shockable rhythms. Overall survival to discharge was 0.75 % (n = 8). Of these 8 patients, 7 patients survived to 1-year and 2 to 5-years. Neurological outcomes correlated with long-term survival. Conclusion: OHCA survival rates are extremely low, necessitating public awareness interventions like CPR training, developing robust pre-hospital systems, and improving in-hospital emergency care through standardized training programs. This pilot registry lays the foundation for implementing interventions to improve survival and emergency medical infrastructure.