Obesity paradox is not recognized in chronic heart failure patients with metabolic syndrome

Abstract

Background: Being overweight or obese is a well-recognized independent risk factor for cardiovascular diseases. However, a number of studies reported that obesity subjects often live longer than lean peers, so-called obesity paradox. Several potential mechanisms have been advocated to explain this paradoxical phenomenon. Given the uncertain role of obesity in the clinical management of some clinical settings, we examined the relationship of obesity to outcomes in chronic heart failure (CHF) patients with and without metabolic syndrome (MetS). The purpose of this study was to clarify the impact of obesity on cardiac prognosis in CHF patients with or without Met. Methods and results: Consecutive 374 patients (mean 68±12 years) were enrolled. Patients were divided into 3 groups (T1-3) according to body mass index (BMI) tertile. After the discharge, the patients were followed 2 years. Endpoints were (1) cardiac death and (2) readmission by worsening heart failure. There were 126 cardiac events (34%) including 32 cardiac deaths and 94 readmission during the follow-up period. Fifty-two patients (14%) with MetS showed lower age and higher BMI compared with those without MetS. Moreover, patients with MetS showed higher serum triglyceride level, higher serum low density lipoprotein cholesterol level, and lower serum high-density lipoprotein cholesterol level compared with those without MetS. There were no significant differences in etiologies of CHF and medication. In all patients and non-MetS patients, serum BNP level was decreased with increasing of BMI (ANOVA p<0.01 each). However, in MetS patients, this tendency was not recognized. Kaplan-Meier analysis revealed that significantly lower cardiac event rates were observed in T3 in all patients and non-MetS patients (log-rank test p<0.001, each). However, in MetS patients, there was no association between BMI and cardiac events. In Cox hazard analysis showed that in all patients and non-MetS patients, T3 (hazard ratio 0.5, 95% CI 0.3-0.8 for all CHF and hazard ratio 0.4, 95% CI 0.3-0.8 for non-MetS) was independently associated with cardiac events after adjustment of age, gender, NYHA functional class and serum BNP level. However, in MetS patients, BMI was not independently associated with cardiac events. Conclusion: Advantage of obesity was not recognized in CHF patients with MetS. Our results provide an important insight into obesity paradox in CHF patients.