Prognostic Outcomes in Acute Myocardial Infarction Patients Without Standard Modifiable Risk Factors: A Multiethnic Study of 8,680 Asian Patients

Background: An increasing proportion of patients with acute myocardial infarction (AMI) are presenting without standard modifiable risk factors (SMuRFs) of hypertension, hypercholesterolemia, diabetes, and smoking, but with an unexpectedly increased mortality. This study examined the SMuRF-less patients presenting with AMI in a multiethnic Asian population.

Methods: We recruited patients presenting with AMI from 2011 to 2021 and compared the prevalence, clinical characteristics, and outcomes of SMuRF-less and SMuRF patients. Multivariable analysis was used to compare the outcomes of 30-day cardiovascular mortality, all-cause mortality, readmission, cardiogenic shock, stroke, and heart failure. Kaplan-Meier curves were constructed for 30-day cardiovascular mortality, with stratification by ethnicity, gender and AMI type, and 10-year all-cause mortality.

Results: Standard modifiable risk factor-less patients, who made up 8.6% of 8,680 patients, were significantly younger with fewer comorbidities that include stroke and chronic kidney disease, but higher rates of ventricular arrhythmias and inotropic or invasive ventilation requirement. Multivariable analysis showed higher rates of cardiovascular mortality (HR 1.48, 95% CI: 1.09-1.86, = 0.048), cardiogenic shock (RR: 1.31, 95% CI: 1.09-1.52, = 0.015), and stroke (RR: 2.51, 95% CI: 1.67-3.34, = 0.030) among SMuRF-less patients. A 30-day cardiovascular mortality was raised in the SMuRF-less group, with similar trends in men, patients with ST-segment elevation myocardial infarction (STEMI), and the three Asian ethnicities. All-cause mortality remains increased in the SMuRF-less group for up to 5 years.

Conclusion: There is a significant proportion of patients with AMI without standard risk factors in Asia, who have worse short-term mortality. This calls for greater focus on the management of this unexpectedly high-risk subgroup of patients.