Short- and long-term outcomes of patients with acute myocardial infarction complicated by cardiac arrest: A nationwide cohort study 2013-2022.

Aim: To assess short- and long-term outcomes of acute myocardial infarction (AMI) complicated by out-of-hospital cardiac arrest (OHCA) or in-hospital cardiac arrest (IHCA) in a nationwide cohort.

Methods: Cohort study of AMI patients admitted to hospitals in Norway 2013-2022 registered in the Norwegian Myocardial Infarction Registry. Outcomes were in-hospital and long-term mortality. Cumulative mortality was assessed with the Kaplan-Meier and the Life-table methods. Cox regression was used for risk comparisons.

Results: Among 105,439 AMI patients (35% women), we identified 3,638 (3.5%) patients with OHCA and 2,559 (2.4%) with IHCA. The mean age was 65.7 (13.2), 70.9 (12.6) and 70.7 (13.6) years for OHCA, IHCA, and AMI without cardiac arrest (CA), respectively. The median follow-up time was 3.3 (25th, 75th percentile; 1.1, 6.3) years. In-hospital mortality was 28%, 49% and 5%, in OHCA, IHCA and AMI without CA, and estimated 5-year cumulative mortality was 48% (95% CI 46-50%), 69% (95% CI 67-71%), and 35% (95% CI 34-35%), respectively. Among patients surviving to hospital discharge, no significant difference in mortality during follow-up was found between OHCA and AMI without CA (adjusted Hazard Ratio (HR) 1.04, 95% CI 0.96-1.13), while the long-term mortality of AMI patients with IHCA was higher (age-adjusted HR 1.31, 95% CI 1.19-1.45).

Conclusion: In this large, contemporary cohort of AMI patients, in-hospital mortality of patients with OHCA or IHCA was still high. Among patients surviving to hospital discharge, long-term mortality was comparable between OHCA and AMI without CA, while the outcome of patients with IHCA was significantly worse.