Clinical profile, risk factors and in-hospital outcomes of ST-segment elevation myocardial infarction in young versus older adults: a 5-year retrospective cohort study at a tertiary care centre in Riyadh, Saudi Arabia

Objectives To compare the clinical profile, cardiovascular risk factor burden, in-hospital management and outcomes of young (≤45 years) versus older (>45 years) adults presenting with ST-segment elevation myocardial infarction (STEMI), and to describe lifestyle factors and disease perceptions among surviving young patients. Design Two-phase retrospective cohort study: Phase I, a review of electronic health record data for all STEMI presentations; Phase II, a structured telephone interview of surviving young patients. Setting A single tertiary care centre with a 24-hour cardiac catheterisation laboratory (King Abdulaziz Medical City, Riyadh, Saudi Arabia), January 2019 to December 2024. Participants 852 consecutive patients with confirmed STEMI; 191 (22.4%) aged ≤45 years (young group) and 661 (77.6%) aged >45 years (older adult group). In Phase II, all 191 young patients were contacted by telephone: 68 (35.6%) completed the interview, 6 (3.1%) declined consent and 117 (61.3%) could not be reached after three attempts on separate days or had an inactive number. Interventions None; this was an observational study. Primary and secondary outcome measures Primary outcome: in-hospital mortality. Secondary outcomes: baseline cardiovascular risk factor prevalence, laboratory parameters, angiographic and procedural characteristics, in-hospital complications, ejection fraction, length of stay and (Phase II) self-reported lifestyle behaviours and perceptions of disease causation. Results The young group was predominantly male (94.8% vs 84.4%; p<0.001) and had significantly higher rates of smoking (71.7% vs 47.5%), obesity (body mass index >29 kg/m²; 33.2% vs 27.2%), illicit drug use (13.6% vs 2.4%) and family history of premature coronary artery disease (11.3% vs 2.2%) (all p<0.001). The older adult group had higher rates of diabetes (62.3% vs 34.6%), hypertension (62.2% vs 28.8%) and dyslipidaemia (47.4% vs 25.7%) (all p<0.001). Mean glycated haemoglobin was lower in the young group (7.05±2.36% vs 7.71±2.27%; p=0.001) but remained above the normal range, and low-density lipoprotein was higher (3.46±1.29 vs 3.19±1.18 mmol/L; p=0.012). In-hospital mortality was lower in the young group (2.1% vs 6.8%; p=0.014), and more young patients maintained an ejection fraction >35% (78.3% vs 68.6%; p=0.011). Among the 68 young survivors interviewed, 74% were people who actively smoked before their STEMI, 72% reported no regular physical activity, 25% used shisha (waterpipe), 16% used e-cigarettes, 28% reported having ‘no idea’ why they had a STEMI, 81% rated their post-STEMI health as good or very good and 37% reported ongoing chest pain. Conclusions Young adults accounted for nearly one-quarter of STEMI presentations and carried a disproportionate burden of modifiable risk factors—smoking, obesity and drug use—alongside unexpectedly poor glycaemic and lipid parameters, despite better short-term survival than older patients. These findings highlight smoking, obesity and adverse metabolic parameters as potential targets for prevention efforts in this population; prospective, interventional studies are needed to determine whether targeted screening or prevention programmes improve outcomes.