Age-dependent risk–treatment mismatch in cancer comorbidity after acute myocardial infarction: nationwide evidence

Introduction Patients with acute myocardial infarction (AMI) and concomitant cancer experience excess in-hospital mortality. Whether this excess risk is consistent across age groups and aligned with invasive management strategies remains unclear. Purpose To assess age-specific associations between cancer comorbidity and in-hospital mortality and percutaneous coronary intervention (PCI) use in patients hospitalised with AMI. Methods This nationwide study used Swiss hospital discharge data (1998–2022). AMI admissions were identified using ICD-10 codes. Cancer comorbidity was defined by malignant neoplasm codes excluding non-melanoma skin cancer. Associations with in-hospital mortality and PCI were estimated using multivariable Poisson regression with robust variance. Age-stratified risk ratios (RRs) and 95% confidence intervals (CIs) were derived from fully adjusted models, and the interaction between cancer and age group was tested. Results Among 356,024 AMI admissions, 7,334 (2.1%) involved cancer comorbidity. In patients <65 years, cancer was associated with a nearly threefold higher in-hospital mortality compared with patients without cancer (RR 2.97, 95% CI 2.37–3.71). This excess mortality attenuated progressively with age and was no longer evident in patients ≥85 years (RR 1.00, 95% CI 0.90–1.12; P for interaction <0.001). In contrast, PCI use was consistently lower among cancer patients across all age groups, with the strongest relative reduction observed in those aged 75–84 years (RR 0.75, 95% CI 0.70–0.79; P for interaction <0.001). Conclusions Cancer comorbidity is associated with a pronounced age-dependent risk–treatment mismatch after AMI. Younger patients with cancer face the highest relative mortality risk despite lower PCI use, whereas the relative excess risk attenuates in the very elderly.