Higher In-Hospital Mortality in SMuRF-Less AMI Patients, Especially Underweight Individuals: CCC-ACS Study

"The highest mortality risk was observed in underweight SMuRF-less patients (OR 3.854), whereas those with obesity and at least one SMuRF had the best survival outcomes, underscoring the impact of BMI on AMI prognosis," the researchers reported in the Journal of the American Heart Association.

Individuals presenting with acute myocardial infarction without standard modifiable cardiovascular risk factors (SMuRF-less) appear to have a significantly higher risk of mortality. However, the influence of baseline body mass index on this "SMuRF paradox" remains unclear.

Jing Liu and colleagues from the Department of Epidemiology and Cardiology, Beijing Anzhen Hospital, Capital Medical University, explored the SMuRF paradox across different BMI categories using data from the CCC-ACS (Improving Care for Cardiovascular Disease in China–Acute Coronary Syndrome) project, the largest ongoing nationwide quality improvement registry for ACS in China. Their study aimed to identify BMI-related disparities in the SMuRF paradox among patients experiencing their first AMI. Using data collected between November 2014 and July 2019, the researchers analyzed patients with and without SMuRFs, categorizing them based on BMI into underweight (<18.5 kg/m²), normal weight (18.5–24 kg/m²), overweight (24–28 kg/m²), and obese (>28 kg/m²).

The primary outcome assessed was in-hospital all-cause mortality, with multivariable logistic regression models used to evaluate BMI-stratified associations between SMuRF-less status and patient outcomes. These findings may enhance risk factor screening and prevention strategies, paving the way for a more personalized approach to AMI care.

Key Findings:

• The study analyzed 44,538 patients with first-presentation acute myocardial infarction, including 4,454 who were SMuRF-less.
• The prevalence of SMuRF-lessness decreased from 16.2% to 6.5% as BMI increased across categories.
• SMuRF-lessness was more common among women and older individuals, regardless of BMI status.
• SMuRF-less patients had significantly higher in-hospital mortality than those with at least one SMuRF (adjusted OR: 1.750).
• The highest mortality rate (3.5%) was observed in underweight SMuRF-less patients.
• Compared to patients with at least one SMuRF and obesity, underweight SMuRF-less individuals had the highest increase in mortality risk (adjusted OR: 3.854).

The findings suggest that patients experiencing their first acute myocardial infarction without any standard modifiable cardiovascular risk factors face a significantly higher risk of in-hospital mortality compared to those with at least one SMuRF. This risk is particularly pronounced among underweight individuals, whereas patients with at least one SMuRF and obesity demonstrated the most favorable in-hospital survival outcomes.

Reference:

Yang Y, Liu Z, Gao F, Ma X, Liu J, Wang Z; CCC‐ACS Investigators. In-Hospital Outcomes in Patients With Acute Myocardial Infarction and No Standard Modifiable Cardiovascular Risk Factors Across Varying Body Mass Index: Findings From the CCC-ACS Project. J Am Heart Assoc. 2025 Mar 26:e037651. doi: 10.1161/JAHA.124.037651. Epub ahead of print. PMID: 40135554.