The obesity paradox in heart failure: is etiology a key factor?

Obesity is paradoxically associated with survival in patients with heart failure (HF). Our objective was to assess whether the relationship between body mass index (BMI) and long-term survival is associated with HF etiology (ischemic vs. non-ischemic) in a cohort of ambulatory HF patients.

BMI and survival status after a median follow-up of 6.1 years (IQR 2.2-7.8) were available for 504 patients (73% men; median age 68 years [IQR 58-74]). Fifty-nine percent of patients had ischemic etiology. Median left ventricular ejection fraction (LVEF) was 30% (IQR 23-39.7%). Most patients were in NYHA functional class II (51%) or III (42%). Patients were divided into four groups according to BMI: low weight (BMI < 20.5 kg/m(2)), normal weight (BMI 20.5 to < 25.5 kg/m(2)), overweight (BMI 25.5 to < 30 kg/m(2)), and obese (BMI ≥ 30 kg/m(2)).

Mortality differed significantly across the BMI strata in non-ischemic patients (log-rank p < 0.0001) but not in ischemic patients. Using normal weight patients as a reference, hazard ratios for low weight, overweight, and obese patients were 2.08 (1.16-3.75, p = 0.014), 0.88 (0.54-1.43, p = 0.60), and 0.49 (0.28-0.86, p = 0.01), respectively, for non-ischemic patients and 1.19 (0.48-2.97, p = 0.71), 0.88 (0.61-1.27, p = 0.48), and 0.96 (0.66-1.41, p = 0.85), respectively, for ischemic patients. After adjusting for age, sex, NYHA functional class, LVEF, co-morbidities, and treatment, BMI remained an independent predictor of survival in non-ischemic patients.

Over long-term follow-up of ischemic and non-ischemic HF, the obesity paradox was only observed in patients with non-ischemic HF.