Relationship between extreme obesity and mortality in patients with reduced ejection fraction

Although obesity is associated with increased mortality, epidemiologic studies in heart failure have reported lower mortality in obese patients compared with matched nonobese patients (the 'obesity paradox'). However, the relationship between survival and extreme (morbid) obesity (BMI ≥ 40) is poorly understood. We evaluate survival in low ejection fraction patients across a range of BMI categories, including extreme obesity.

In a retrospective review, 12 181 consecutive patients receiving nuclear stress testing at a tertiary care center were stratified based on BMI and ejection fraction. Eight-year mortality data were collected using the social security death index.

Normal ejection fraction patients (internal control, ejection fraction ≥50%) exhibited the J-shaped association between mortality and BMI that is observed in the general population. Among patients with reduced ejection fraction (<50%), survival improved as obesity increased (P < 0.0001). Those with extreme obesity had the lowest mortality (n = 1134, P < 0.05).

In this cohort of reduced Ejection fraction patients, the obesity paradox was observed in all weight categories, with the highest survival of all observed in the extremely obese BMI category. This further supports hypotheses that an obesity-related physiologic phenomenon affects mortality in reduced ejection fraction patients.