Studies document better survival in heart failure patients with decreased left ventricular ejection fraction (EF) and higher body mass index (BMI; kg/m²) compared to those with a lower BMI. However, it is unknown if this “obesity paradox” applies to heart failure patients with preserved EF or if it extends to the very obese (BMI >35).

We determined all-cause mortality for 1,236 consecutive patients with a prior diagnosis of heart failure and a preserved EF (≥50%).

Obesity (BMI>30) was noted in 542 patients (44%). The mean age was 71 ± 12 years, but this varied depending on BMI. One-year all-cause mortality decreased with increasing BMI, except at BMI >45 where mortality began to increase (55% if BMI <20, 38% if BMI 20-25, 26% if BMI 26-30, 25% if BMI 31-35, 17% if BMI 36-40, 18% if BMI 41-45, and 25% if BMI>45, P < .001). After adjustment for patient age, history, medications, and laboratory and echocardiographic parameters, the hazard ratios for total mortality (relative to BMI 26-30) were 1.68 (95% CI, 1.04-2.69) for BMI <20, 1.25 (95% CI, 0.92-1.68) for BMI 20 to 25, 0.99 (95% CI, 0.71-1.36) for BMI 31-35, 0.58 (95% CI, 0.35-0.97) for BMI 36 to 40, 0.79 (95% CI, 0.44-1.4) for BMI 41 to 45, and 1.38 (95% CI 0.74-2.6) for BMI >45 (P < .0001).

Low BMI is associated with increased mortality in patients with heart failure and preserved systolic function. However, with a BMI of >45, mortality increased, raising the possibility of a U-shaped relationship between BMI and survival.