Comparison of In-Hospital Outcomes of Acute ST Segment Elevation Myocardial Infarction in Young Versus Older Patients

Background Acute ST-segment elevation myocardial infarction remains a major cause of early hospital complications and death. Although it is more common in older patients, young adults are increasingly presenting with ST-segment elevation myocardial infarction (STEMI). Age may influence risk factors, clinical presentation, coronary anatomy, treatment response, and short-term outcomes, making comparison between young and older patients clinically important. This study aimed to compare in-hospital outcomes of acute ST-segment elevation myocardial infarction between young and older patients and identify independent predictors of in-hospital mortality. Methods This prospective analytical observational study was conducted in the Department of Cardiology at a tertiary care hospital in Lahore, over 12 months. A total of 300 patients with acute STEMI presenting within 12 hours of symptom onset were enrolled by non-probability consecutive sampling and divided into young patients aged ≤40 years and older patients aged >40 years, with 150 patients in each group. Demographic characteristics, cardiovascular risk factors, clinical presentation, laboratory profile, electrocardiogram (ECG), echocardiographic and angiographic findings, reperfusion details, procedural variables, and in-hospital outcomes were recorded. Data were analyzed using SPSS version 26.0 (IBM Corporation, Armonk, USA); Chi-square, Fisher's exact, independent samples t-test, Mann-Whitney U test, and multivariable logistic regression were applied. Results Of 300 patients with STEMI, 150 were included in each age group. Young patients were more frequently male than older patients, 131 (87.3%) versus 116 (77.3%) (p=0.023), and had higher smoking frequency, 86 (57.3%) versus 53 (35.3%) (p<0.001), and a family history of cardiovascular disease, 36 (24.0%) versus 16 (10.7%) (p=0.002). Older patients had a greater comorbidity burden, including higher diabetes, hypertension, dyslipidemia, cerebrovascular events, and chronic kidney disease (all p<0.001), and more dyspnea, 73 (48.7%) versus 34 (22.7%) (p<0.001). Anterior STEMI, 85 (56.7%) versus 57 (38.0%) (p=0.001), left anterior descending artery (LAD) involvement, 81 (54.0%) versus 58 (38.7%) (p=0.008), and single-vessel disease, 107 (71.3%) versus 79 (52.7%) (p=0.001), were more frequent in young patients, whereas triple-vessel disease was higher in older patients, 26 (17.3%) versus 9 (6.0%) (p=0.002). Older patients had higher heart failure, 40 (26.7%) versus 16 (10.7%) (p<0.001), cardiogenic shock, 21 (14.0%) versus 7 (4.7%) (p=0.006), acute kidney injury (AKI), 24 (16.0%) versus 7 (4.7%) (p=0.001), mechanical complications, 19 (12.7%) versus 5 (3.3%) (p=0.003), and in-hospital death, 17 (11.3%) versus 6 (4.0%) (p=0.017). On multivariable analysis, mechanical complications [adjusted odds ratio (AOR) 13.13; p<0.001], ventricular arrhythmias (AOR 10.57; p<0.001), cardiogenic shock (AOR 6.25; p=0.010), and AKI (AOR 4.84; p=0.028) independently predicted in-hospital mortality, while the older age group was not independently associated with mortality (p=0.801). Conclusion Older STEMI patients had more adverse in-hospital outcomes, mainly due to acute complications and comorbidity burden. Mortality was independently related to mechanical complications, ventricular arrhythmias, cardiogenic shock, and AKI rather than age group alone.