Prognosis of a malignant phenotype of obesity defined by a cardiac biomarker in hypertension: the Japan Morning Surge-Home Blood Pressure study

Obesity with increased high-sensitive cardiac troponin T (hs-cTnT) has been reported to be more likely to progress cardiovascular disease (CVD) events, which suggests that hs-cTnT may identify a "malignant" phenotype of obesity. We classified 3513 hypertensive patients from the Japan Morning Surge-Home Blood Pressure (J-HOP) study into groups based on body mass index (BMI) (normal weight: <25 kg/m(2), overweight: 25-29.9 kg/m(2), obesity: >= 30 kg/m(2)) and elevations in biomarker levels (hs-cTnT >= 3 ng/mL: 51.3%, 54.9%, 53.3%, and N-terminal pro-brain natriuretic peptide [NT-ProBNP] >= 55 pg/mL: 51.1%, 40.7%, 36.0% in each BMI category). We evaluated the independent and combined associations of BMI and each hs-cTnT/NT-proBNP or both with CVD events (fatal and nonfatal coronary artery disease, stroke, and hospitalized heart failure). During the mean 6.4 +/- 3.9-year follow-up, 232 CVD events occurred. Obesity with elevated hs-cTnT was associated with a risk of CVD events compared to normal weight without elevated hs-cTnT (hazard ratio 3.22, 95% confidence interval: 1.83-5.68). A similar pattern of results was also observed across the status of obesity and elevated NT-proBNP. There was a significant interaction between hs-cTnT and CVD events according to the obesity status (p = 0.039), while this association was marginal in NT-proBNP (p = 0.060). The magnitude of the mediation of hs-cTnT for the association between obesity and CVD risk was 41.2%, and that for NT-proBNP was 8.1%. In this Japanese hypertensive population, the elevation of hs-cTnT identified obese patients at particularly high risk for developing CVD events, suggesting that hs-cTnT may identify a 'malignant' phenotype of obesity.