Age and Clinical Context in Acute Myocardial Infarction–Related Cardiogenic Shock: Prognostic Differences by Out-of-Hospital Cardiac Arrest

Structured Abstract Background Cardiogenic shock (CS) remains a leading cause of in-hospital mortality in acute myocardial infarction (AMI). Although advanced age is associated with worse outcomes, the prognostic relevance of chronological age may vary by clinical presentation, particularly in the presence of out-of-hospital cardiac arrest (OHCA). We investigated the prognostic impact of octogenarian status in patients with AMI complicated by cardiogenic shock (AMI–CS). Methods We analyzed patients with AMI–CS enrolled in the multicenter Kanagawa-ACuTe cardIoVascular rEgistry (K-ACTIVE) who underwent percutaneous coronary intervention (PCI). Octogenarian status (≥80 years) was the primary exposure. Multivariable logistic regression was used to evaluate associations with in-hospital mortality, and effect modification by OHCA was assessed. Model performance was evaluated using discrimination and decision curve analysis. Results Among 658 patients with AMI–CS, 177 (26.9%) were octogenarians, and 279 (42.4%) died during hospitalization. In the primary multivariable analysis, octogenarian status was independently associated with higher in-hospital mortality (adjusted odds ratio [aOR], 2.09; 95% CI, 1.33–3.27). This association was evident among patients without OHCA, whereas no clear age-related gradient was observed among those presenting with OHCA. In multivariable models, heart rate and serum albumin provided incremental prognostic information beyond chronological age. Conclusion In patients with AMI–CS, the prognostic impact of advanced age varies according to clinical presentation. While advanced age confers excess risk among patients without OHCA, its prognostic value appears limited among those presenting after cardiac arrest. These findings support risk stratification strategies that integrate physiological markers beyond chronological age alone to guide individualized clinical decision-making. Key Points The prognostic impact of age in acute myocardial infarction complicated by cardiogenic shock is highly context dependent. Octogenarian status was associated with increased mortality among patients without out-of-hospital cardiac arrest (OHCA), whereas no meaningful association was observed among those presenting with OHCA. Unmeasurable vital signs, particularly heart rate, represent clinically meaningful physiological derangement rather than missing data. These parameters added prognostic information beyond that provided by conventional clinical variables. Serum albumin and heart rate, which are routinely available at presentation, appeared to capture aspects of physiological vulnerability not fully explained by chronological age alone. Clinical Perspective What Is New? The prognostic relevance of age in AMI complicated by cardiogenic shock (AMI–CS) was not uniform and differed according to clinical presentation. Octogenarians exhibit substantially higher mortality among patients without OHCA, whereas age did not meaningfully influence mortality after OHCA. Unmeasurable vital signs represent clinically informative, missing-not-at-random indicators of disease severity. Explicit modeling of unmeasurable systolic blood pressure and heart rate strengthened prognostic assessment. Serum albumin and heart rate provide prognostic information beyond chronological age in AMI–CS. What Are the Clinical Implications? Chronological age alone should not determine the aggressiveness of care in patients with AMI–CS. Among patients without OHCA, advanced age may identify a biologically vulnerable subgroup that could benefit from timely revascularization and selectively applied mechanical circulatory support. In patients with OHCA, prognosis appears to be driven predominantly by post–cardiac arrest injury rather than age. Incorporating serum albumin and heart rate into risk assessment may support more equitable, phenotype-based clinical decision-making.