Abstract 156: Incidence and Long-Term Outcomes of Acute Myocardial Infarction Among Survivors of Out-of-Hospital Cardiac Arrest

Abstract

Introduction: Despite the increasing long-term survival after out-of-hospital cardiac arrest (OHCA), the risk of subsequent acute myocardial infarction (AMI) remains poorly understood. We aimed to determine the incidence, predictors, and long-term outcomes of AMI among OHCA survivors. Methods: We assembled a retrospective cohort of patients with OHCA who survived to 30 days or discharge from hospital regardless of time from index event between 2010-2019 by linking the Pan-Asian Resuscitation Outcomes Study (Singapore participants), Singapore Myocardial Infarction Registry, and the Singapore Registry of Births and Deaths. We calculated the risk of subsequent AMI defined as AMI occurring 30 days after index OHCA or following discharge from hospital post-OHCA, among OHCA survivors compared to the general population using age- and sex-specific standardised incidence ratios (SIR) and the cumulative incidence of subsequent AMI among OHCA survivors. We investigated predictors of subsequent AMI among OHCA survivors and whether AMI predicted mortality using Cox regression hazard ratios for time-to-event analyses. Results: In total, 882 OHCA survivors were analysed. OHCA survivors had an increased risk of subsequent AMI compared to the general population when matched for age and sex (SIR 4.64, 95% CI: 3.52-6.01). Age-specific risks of subsequent AMI for males (SIR 3.29, 95%CI: 2.39-4.42) and females (SIR 6.15, 95%CI: 3.27-10.52) were significantly increased. 7.2%, 8.3%, and 14.3% of OHCA survivors had subsequent AMI at 3 years, 5 years, and end of follow-up respectively. Age at OHCA (HR 1.04, 95%CI: 1.02-1.06) and past medical history of prior AMI, defined as any AMI preceding or during the index OHCA event (HR 1.84, 95%CI: 1.05-3.22), were associated with subsequent AMI. OHCA survivors with subsequent AMI had a higher risk of mortality (HR 1.58, 95%CI: 1.12-2.22) than those without. Conclusion: Long-term OHCA survivors have an increased risk of subsequent AMI, compared to the general population. Prior AMI significantly increases this risk and subsequent AMI predicts mortality. Intensive cardiovascular risk factor control and revascularisation may improve outcomes in selected patients with a cardiac etiology.