Delays in Early Defibrillation in Out-of-Hospital Cardiac Arrest: A Scoping Review from a Systems and Public Health Perspective

Background/Objectives: Early defibrillation is critical for survival after out-of-hospital cardiac arrest (OHCA), yet delays arise from interacting community, organizational, dispatch, and emergency medical services (EMS) factors. This scoping review mapped determinants of delayed defibrillation, examined temporal measurement approaches, and summarized associations with clinical outcomes. Methods: A preregistered scoping review was conducted following Joanna Briggs Institute guidance and PRISMA-ScR reporting standards. PubMed/MEDLINE, Scopus, and CINAHL were searched in February 2026. Two reviewers independently screened records, and extracted data were cross-checked. Evidence was synthesized descriptively across system-level domains and temporal categories. Results: Of 4456 records identified, 82 studies were included, predominantly observational (75/82, 91.5%). Determinants were classified as community-related (32/82, 39.0%), system-related (26/82, 31.7%), dispatch-related (18/82, 22.0%), and EMS-related (6/82, 7.3%). Fifty-two studies reported classifiable temporal metrics. Among 48 studies linking timing or early-defibrillation determinants with outcomes, 31 examined direct or multiple shock-related intervals, two examined upstream operational response times, and 15 used indirect indicators. Of the 31 studies assessing direct or multiple shock-related intervals, 30 (96.8%) indicated more favorable outcomes with shorter timing. All 28 studies using a single direct shock-related interval showed directional concordance. Conclusion. Defibrillation delays reflect interconnected system-level processes rather than EMS response time alone. Standardized temporal measurement, integrated AED and responder networks, and targeted strategies addressing geographic and socioeconomic disparities may support earlier defibrillation. These findings have implications for emergency-care organization, interprofessional coordination, and nursing education in resuscitation systems.