Higher BMI was associated with a significantly lower risk of recurrent myocardial infarction in AMI patients aged ≤60 years (HR 0.965; 95% CI 0.936-0.994; P=0.018), but not in those >60 years.
Cohort (n=4,023)
No
Does higher BMI reduce the risk of recurrent myocardial infarction in patients with acute myocardial infarction, and does this effect vary by age?
An age-dependent obesity paradox exists in AMI patients, where higher BMI is associated with reduced recurrent MI risk in patients ≤60 years but not in those >60 years.
Effect estimate: HR 0.965 (95% CI 0.936-0.994)
p-value: p=0.018
BACKGROUND: Obesity is a known cardiovascular risk factor, but the "obesity paradox" has been observed in patients with acute myocardial infarction (AMI), where obesity may be linked to better survival outcomes. The relationship between body mass index (BMI) and recurrent myocardial infarction, particularly with age-specific effects, remains unclear. METHODS: This retrospective cohort study included 4023 AMI patients from a tertiary medical center (2015-2023). Patients were stratified by age: ≤60 years (n = 1277) and >60 years (n = 2746). Multivariable-adjusted Cox proportional hazards models were used to assess the association between BMI and recurrent myocardial infarction, adjusting for demographics, biomarkers N-terminal pro-B-type natriuretic peptide (NT-proBNP), high-sensitivity cardiac troponin T (hs-cTnT), imaging parameters left ventricular ejection fraction (LVEF), comorbidities, and treatment regimens. Curve-fitting models were also applied. The median follow-up time was 35 months (Q1-Q3 25-58). RESULTS: In the ≤60 years group, higher BMI was associated with a significantly lower risk of recurrent myocardial infarction adjusted hazard ratio (HR) = 0.965, 95% confidence interval (CI) 0.936-0.994, P = 0.018. In contrast, the >60 years group showed a trend toward higher risk (unadjusted HR = 1.032, 95% CI 1.012-1.053, P = 0.001), which lost statistical significance after adjustment (adjusted HR = 1.015, 95% CI 0.994-1.037, P = 0.151). Curve fitting revealed a negative linear correlation in the ≤60 years group and a positive relationship in the >60 years group. CONCLUSIONS: This study presents the first evidence of an age-dependent obesity paradox in AMI. In patients aged ≤60 years, higher BMI reduced recurrent myocardial infarction risk, whereas in those aged >60 years, the protective effect disappeared and reversed, indicating potential harm. These findings highlight the need for age-stratified secondary prevention strategies for AMI. Summary of Principal Study Outcomes.
Zhang et al. (Sat,) conducted a cohort in Acute myocardial infarction (n=4,023). Body mass index (BMI) was evaluated on Recurrent myocardial infarction (HR 0.965, 95% CI 0.936-0.994, p=0.018). Higher BMI was associated with a significantly lower risk of recurrent myocardial infarction in AMI patients aged ≤60 years (HR 0.965; 95% CI 0.936-0.994; P=0.018), but not in those >60 years.