Heart-Failure Phenotypes, Not Chronological Age, Determine Mortality Risk in Octogenarians With Acute Myocardial Infarction

Background: The ageing population has led to more octogenarians experiencing acute myocardial infarction (AMI). Whether age or underlying myocardial dysfunction drives mortality in this population is understudied. We evaluated the impact of age versus cardiac dysfunction on mortality in octogenarians with AMI.Methods: We incorporated AMI patients undergoing coronary angiography from 2004-2019 and stratified them by age ≥ 80 years. All-cause mortality was assessed over median 1.18 years (IQR 0.30–3.86). Multivariable-adjusted Cox regression evaluated age-mortality associations, and Kaplan–Meier analyses assessed survival by natriuretic-peptide levels, left ventricular (LV) ejection fraction (EF), and diastolic function (E/e’).Results: Of 2276 patients (mean age 65.9±13.2years, 73.7%male), 341 (15%) were ≥80. Octogenarians had more multivessel disease, longer ischemia and fluoroscopy times, extended hospitalizations, higher acute kidney injury incidence, and greater impairment in LVEF and myocardial deformation, with more significant mitral regurgitation (all p<0.05). Age ≥80 was associated with higher 30-day, 1-year, and long-term mortality after adjustment for conventional cardiovascular risk factors (HRs 1.97 [1.38–2.82], 1.89 [1.41–2.53], and 1.95 [1.54–2.48]; all p<0.05), but not after ancillary adjustment for natriuretic-peptides. Octogenarians with low natriuretic-peptides or preserved systolic and diastolic function had survival comparable to younger patients, whereas elevated peptides, LVEF<40%, or E/e&apos;≥14 identified higher-risk subgroups (all log-rank p<0.001).Conclusions: In octogenarians with AMI, increased mortality is mediated by reverse causation: the effect of age is driven by heart-failure severity, manifested by elevated natriuretic-peptides and impaired LV systolic or diastolic function. Functional- and biomarker-based, precision-focused prognostic strategy should guide management in octogenarians.​