ObjectiveThis study describes the differences in treatment and clinical outcomes in patients aged ≥75 years compared with those aged ≤74 years presenting with acute coronary syndrome (ACS) and undergoing invasive management.MethodsA large-scale cohort study of patients with ST-elevation/non-ST-elevation myocardial infarction (MI)/unstable angina underwent coronary angiography (January 2015–December 2019). Patients were classified as older (≥75 years) and younger (≤74 years). Regression analysis was used to yield adjusted risks of mortality for older versus younger patients (adjusted for history of heart failure, hypercholesterolaemia, peripheral vascular disease, chronic obstructive pulmonary disease, ischaemic heart disease, presence of ST-elevation MI on presenting ECG, female sex and cardiogenic shock at presentation).ResultsIn total, 11 763 patients were diagnosed with ACS, of which 39% were aged ≥75 years. Percutaneous coronary intervention was performed in fewer older patients than younger patients (81.2% vs 86.2%, p<0.001). At discharge, older patients were prescribed less secondary-prevention medications than younger patients. Median follow-up was 4.57 years. Older patients had a greater risk of in-hospital mortality than younger patients (adjusted OR (aOR) 2.12, 95% CI 1.62 to 2.78, p<0.001). Older patients diagnosed with ST-elevation MI had greater adjusted odds of dying in-hospital (aOR 2.47, 95% CI 1.79 to 3.41, p<0.001). Older age was not an independent prognostic factor of mortality at 1 year (adjusted HR (aHR) 0.95, 95% CI 0.82 to 1.09, p=0.460) and at longer term (aHR 0.98, 95% CI 0.87 to 1.10, p=0.684).ConclusionsOlder patients are discharged with less secondary prevention. Patients aged ≥75 years are more likely to die in-hospital than younger patients.