Patients who were overweight or obese before developing heart failure (HF) lived longer than those who developed HF at a normal weight, according to a study published Dec. 22 in the Journal of the American College of Cardiology.

These findings support the “obesity paradox” first evidenced over a decade ago, which suggests that patients with obesity prior to their diagnosis of HF have higher rates of survival. Prior to the findings of this study, it was unclear whether this survival rate was connected to weight loss after the diagnosis of HF or other additional mechanisms, such as “pre-existing obesity with…greater metabolic reserve” prior to incident HF.

Using data from the Atherosclerosis Risk in Communities study, Umair Khalid, MD, and his colleagues compared body mass index (BMI) of overweight (BMI 25—<30 kg/m2), obese (≥30 kg/m2) and normal weight (18.5—<25 kg/m2) patients, measured less than six months before incident HF, in order to evaluate the association of BMI and mortality after diagnosis. Of the 1,487 patients who developed HF, 35 percent were overweight and 47 percent were obese. Over the follow-up period of 10 years, 43 percent of all patients died. Despite 51 percent of normal weight HF patients dying, only 45 percent of overweight and 38 percent of obese patients died after 10 years.

The results of the study show that patients classified as pre-morbidly overweight have lower mortality after the diagnosis of HF than those with normal weight. The authors note that these findings are consistent across patients with histories of cancer, smoking and diabetes. Further, the study results suggest that overweight and obese HF patients possibly have a higher metabolic reserve which aids in survival when cardiac cachexia occurs, compared to those patients with normal weight. 

“Most patients with HF have pre-existing overweight or obesity, yet they have lower mortality compared to normal body mass index heart failure patients,” said the study’s senior author, Anita Deswal, MD, MPH, FACC, of the Michael E. DeBakey VA Medical Center and Baylor College of Medicine in Houston. “Our findings suggest that a major component of the so-called obesity paradox is premorbid obesity and it’s unlikely that spontaneous weight loss due to advanced heart failure is the only contributing factor to the obesity paradox.”

In an accompanying commentary, Thomas J. Wang, MD, FACC, notes that “to understand obesity’s physiological consequences in HF, further work is warranted in both experimental and human studies, with the latter collecting more detailed metabolic and physiological data…Incorporating even more detailed metabolic phenotyping in HF studies…could provide further insight. Ultimately a better mechanistic understanding of what drives the obesity paradox should serve as the basis for postulating whether an optimal BMI exists for HF patients.”

Clinical Topics: Heart Failure and Cardiomyopathies, Acute Heart Failure

Keywords: Atherosclerosis, Body Mass Index, Body Weight, Cachexia, Heart Failure, Overweight, Survival Rate, Weight Loss

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