Shockable Versus Non-Shockable Rhythms and Hospital Outcomes among Adults Achieving ROSC after In-Hospital Cardiac Arrest: A Retrospective Cohort Study

Abstract

Objective: To compare survival to hospital discharge and favourable recorded neurological outcome between initial shockable and non-shockable rhythms among adults who achieved sustained ROSC following IHCA. Methodology: This retrospective cohort study included adults aged 18–74 years who experienced IHCA, had a recorded cardiopulmonary resuscitation (CPR) duration ≤40 minutes, and achieved sustained ROSC for ≥20 minutes at a tertiary cardiology centre between January 2024 and January 2025. Sequential Firth penalised logistic-regression models estimated unadjusted, baseline-adjusted, and CPR-duration-adjusted associations between initial rhythm and survival to hospital discharge and favourable recorded Cerebral Performance Category (CPC) 1–2. Results: Among 75 patients, 35 (46.7%) had shockable and 40 (53.3%) had non-shockable rhythms. Median recorded CPR duration was shorter in the shockable group (6.0 [IQR 4.0–10.0] vs 15.5 [IQR 10.0–20.0] minutes; p<0.001). Survival to hospital discharge was 68.6% versus 27.5%, while favourable recorded CPC occurred in 55.9% versus 17.5%, respectively. Shockable rhythm was associated with higher unadjusted odds of discharge survival (OR 5.47, 95% CI 2.11–15.07; p<0.001) and favourable recorded CPC (OR 5.62, 95% CI 2.07–16.66; p<0.001). After baseline adjustment and additional inclusion of CPR duration, corresponding estimates were attenuated to OR 2.16 (95% CI 0.70–6.64; p=0.179) and OR 2.52 (95% CI 0.80–8.19; p=0.116). Conclusion: Among adults achieving sustained ROSC after IHCA, initial shockable rhythm was associated with substantially better unadjusted and baseline-adjusted hospital and recorded neurological outcomes. These associations attenuated after inclusion of CPR duration, which may represent arrest severity or an intermediate variable. The findings apply specifically to patients achieving sustained ROSC and should not be interpreted as the overall prognostic effect of initial rhythm among all patients experiencing IHCA.