Background and Aims: While obesity has been linked to better ouctomes (the obesity paradox), cachexia is associated with higher mortality in patients with heart failure with reduced ejection fraction (HFrEF). As opposed to overt cachexia, little is known about the prognostic impact of gradual, long-term weight changes in stable HFrEF.

Methods and Results: We included ambulatory patients with clinically stable chronic HFrEF on individually optimized treatment. Next to other clinical and functional parameters, changes in body weight over the past one (n=733, group 1) or two (n=636, group 2) years were recorded. Four-year mortality was analysed with respect to baseline BMI and changes in body weight or BMI using fractional polynomials. In addition, outcome was stratified by BMI categories (18.5-25 kg/m²: normal weight, >25-30 kg/m²: overweight, >30 kg/m²: obesity).

An obesity paradox was present in both groups, with overweight and obese patients having the best prognosis. In both groups, a gradual weight gain of 5% was associated with the lowest mortality, whereas mortality steadily increases with increasing weight loss. Excessive weight gain >10% was also related to higher mortality. Stratification by baseline BMI categories revealed that weight loss was most detrimental in normal weight patients, whereas the prognostic impact of weight change was weaker in obese patients.

Conclusion: In patients with chronic HFrEF, gradual weight loss is associated with steadily increasing mortality, whereas a weight gain of 5% is related to the best prognosis. Prevention of any inappropriate weight loss might be a therapeutic goal in HFrEF patient care.