Myocardial Injury, Obesity, and the Obesity Paradox: The ARIC Study

Objectives This study sought to determine whether pre-heart failure (HF) myocardial injury explains the differential mortality after HF across weight categories. Background Obesity is a risk factor for HF, but pre-HF obesity is associated with lower mortality after incident HF. High-sensitivity cardiac troponin T (hs-cTnT) is a sensitive marker of myocardial injury, and predicts incident HF and mortality. Methods Stratifying 1,279 individuals with incident HF hospitalizations by their pre-HF hs-cTnT levels (< and ≥ 14 ng/l), we examined the association of pre-HF body mass index (BMI) with mortality after incident HF hospitalization in the ARIC (Atherosclerosis Risk In Communities) study. Results Mean age at HF was 74 years (53% women, 27% black). Individuals with pre-HF hs-cTnT ≥14 ng/l had higher mortality after incident HF (hazard ratio [HR]: 1.46; 95% confidence interval [CI]: 1.18 to 1.80) compared to individuals with hs-cTnT <14 ng/l in an adjusted model including BMI. Compared with normal weight subjects, the mortality was lower in overweight (HR: 0.69, 95% CI 0.48-0.98) and obese individuals (HR: 0.50; 95% CI: 0.35 to 0.72) with hs-cTnT <14 ng/l; and in those with hs-cTnT ≥14 ng/l (overweight HR: 0.50; 95% CI: 0.30 to 0.83; obese HR: 0.56; 95% CI: 0.34 to 0.91; interaction: p = 0.154 between BMI and hs-cTnT). The lower mortality risk in obese and overweight subjects remained similar when log hs-cTnT was added as a continuous variable to a multivariable model, and in sensitivity analyses after further adjusting for left ventricular hypertrophy or high-sensitivity C-reactive protein. Conclusion Although greater pre-existing subclinical myocardial injury was associated with higher mortality after incident HF hospitalization, it did not explain the obesity paradox in HF, which was observed irrespective of subclinical myocardial injury.