Prognostic Outcomes in Acute Coronary Syndrome Patients Without Standard Modifiable Risk Factors: A Multi-Ethnic Study Of 8680 Asian Patients

Abstract IMPORTANCE There are growing concerns that patients suffering from acute coronary syndrome (ACS) without standard modifiable cardiovascular risk factors (SMuRFs), including hypertension, hypercholesterolemia, diabetes and smoking, have increased mortality. OBJECTIVE This study examined the outcomes of ACS in patients without SMuRFs (termed SMuRF-less) in a multi-ethnic Asian population which remains unknown. DESIGN This retrospective study was conducted from 1 st January 2011 to 31 st March 2021. SETTING This study was conducted in a tertiary healthcare institution in Singapore. PARTICIPANTS Consecutive patients presenting with ACS disease were recruited in the study. EXPOSURE The outcomes of SMuRF-less patients were compared with SMuRF patients. MAIN OUTCOMES AND MEASURES The primary outcome was cardiovascular mortality. Secondary outcomes were all-cause mortality, readmission, cardiogenic shock, stroke and heart failure. Multivariable regression analysis adjusted for covariates including age, sex, ethnicity, chronic kidney disease, ACS type, cardiac arrest, and left main and/or left anterior descending coronary RESULTS Of the 8680 patients studied, 8.6% were SMuRF-less patients. SMuRF-less patients were significantly younger and had fewer comorbidities including stroke and chronic kidney disease, but higher rates of ventricular arrhythmias and inotropic or invasive ventilation requirement compared to the SMuRF group. Multivariable analysis showed higher rates of cardiovascular mortality (HR 1.48, 95% CI 1.09–1.86, p=0.048), cardiogenic shock (RR: 1.31, 95% CI 1.09–1.52, p=0.015) and stroke (RR: 2.51, 95% CI 1.67–3.34, p=0.030) in SMuRF-less patients compared to SMuRF patients. Both groups had similar readmission (RR: 1.10, 95% CI 0.87–1.39, p=0.413) and heart failure (RR: 0.82, 95% CI 0.56–1.21, p=0.326) rates. Kaplan-Meier curve showed higher 30-day cardiovascular mortality in the SMuRF-less group compared to SMuRF group (HR: 1.84, 95% CI 1.45-2.33, p<0.001), with similar significant trends found in men, STEMI patients, and the three Asian ethnicities. CONCLUSION AND RELEVANCE Although the proportion of ACS patients without standard risk factors in our Asian population is lower than those reported in the West, they also have worse short-term mortality compared to those with SMuRF. This calls for a global focus on the management of this unexpectedly high-risk subgroup of patients.