Clinical outcomes and coronary artery lesion characteristics of young patients with ST elevation myocardial infarction and no standard modifiable risk factors.

Background: Among ST-elevation myocardial infarction (STEMI) patients, those with no standard modifiable risk factors (SMuRFs: hypertension, diabetes mellitus, hypercholesterolemia, and smoking) have higher 30-day mortality than those with SMuRFs. Differences in coronary lesion characteristics remain unclear.

Methods: Data from STEMI patients aged ≤60 years from the Asia Pacific Evaluation of Cardiovascular Therapies Network (Australia, Hong Kong, Malaysia, Singapore, and Vietnam) was retrospectively analysed. Exclusion criteria included incomplete SMuRF data, prior myocardial infarction, or prior coronary revascularisation. Lesion type was defined using the American College of Cardiology criteria. Major adverse cardiovascular events (MACE) were defined as peri-procedural myocardial infarction, emergency coronary artery bypass surgery, cerebrovascular event, or mortality. Multiple logistic regressions were used.

Results: Of 4404 patients, 767 (17.4%) were SMuRFless. SMuRFless patients were more frequently younger (median age 51 vs. 53 years; p < 0.001), female (22.6% vs. 15.5%; p < 0.001), thrombolysed (20.1% vs. 12.5%; p < 0.001), and in cardiogenic shock (11.2% vs. 8.6%; p = 0.020). SMuRFless patients had significantly higher in-hospital MACE (7.2% vs. 4.3%; adjusted odds ratio [aOR] 2.25; 95% confidence interval [CI] 1.24-4.08; p = 0.008) but 1-year mortality was not significantly different (3.6% vs. 5.7%, aOR 0.58; 95% CI 0.06-6.12; p = 0.549). Compared with patients with SMuRFs (4918 lesions), the SMuRFless (940 lesions) had fewer type B2/C lesions (60.8% vs. 65.6%; p = 0.020) and fewer lesions ≥20 mm (51.1% vs. 57.1%; p = 0.002) but more procedural complications (5.1% vs. 2.7%; p < 0.001).

Conclusions: Among young STEMI patients, the SMuRFless have shorter and less complex lesions, but worse procedural and short-term MACE outcomes.