Association between the body mass index and the clinical findings in patients with acute heart failure: evaluation of the obesity paradox in patients with severely decompensated acute heart failure.

Obesity is known to be associated with the development of heart failure (HF). However, the relationship between the body mass index (BMI) and acute HF (AHF) remains to be elucidated. Eight hundred and eight AHF patients were enrolled in this study. The patients were assigned to four groups according to their BMI values: severely thin (n = 11, BMI <16), normal/underweight (n = 579, 16 ≤ BMI <25), overweight (n = 178, 25 ≤ BMI <30) and obese (n = 40, BMI ≥30). The patients in the severely thin group were more likely to be female, have systolic blood pressure (SBP) <100 mmHg and have valvular disease than normal/underweight patients. The patients in the overweight group were significantly younger than those in the normal/underweight, and those in the overweight group were more likely to have SBP ≥140 mmHg and hypertensive heart disease and less likely to have valvular disease than the patients in the normal/underweight group. The prognosis, including all-cause death, was significantly poorer among patients who were severely thin than those who were normal/underweight, overweight and significantly better among those who were overweight than those who were normal/underweight, severely thin and obese patients. A multivariate Cox regression model identified that severely thin [HR: 3.372, 95% confidence interval (CI) 1.362-8.351] and overweight (HR: 0.615, 95% CI 0.391-0.966) were independent predictors of 910-day mortality as the reference of normal/underweight. Overweight patients tended to have SBP ≥140 mmHg and be relatively young, while severely thin patients tended to have SBP <100 mmHg and be female. These factors were associated with a better prognosis of overweight patients and adverse outcomes in severely thin patients. These factors may contribute to the "obesity paradox" in severely decompensated AHF patients.