It may seem counterintuitive, but when it comes to a person surviving heart failure, a big waist may be an advantage. Researchers at UCLA have found that in both men and women with advanced heart failure, obesity and a higher waist circumference were factors that put them at significantly less risk for adverse outcomes.
The study was published in the American Journal of Cardiology.
The findings offer further insight into an observed phenomenon in chronic heart failure known as the "obesity paradox": Obesity is a known risk factor for developing heart disease and heart failure, but once heart failure has manifested, being overweight may provide some benefits.
"Heart failure may prove to be one of the few health conditions where extra weight may be protective," says Tamara Horwich, M.D. '07, assistant professor of cardiology.
Researchers analyzed data on advanced-heart-failure patients treated at UCLA from 1983 to 2011. The team assessed 2,718 patients who had their body mass index (BMI) measured at the beginning of heart failure treatment and 469 patients who had their waist circumference measured at the beginning of treatment.
At the two-year follow-up, researchers used statistical analysis and found that in men, a high waist circumference and high BMI were associated with event-free survival from adverse outcomes like the need for a heart transplant, the need for ventricular-assist-device placement, or even death. Women with a higher BMI also had better outcomes than their normal-weight counterparts, and women with a high waist circumference also trended toward improved outcomes.
No one knows exactly why the obesity paradox exists, but there are several possible explanations. Patients who are obese may, for example, benefit from increased muscle mass, as well as metabolic reserves in the form of fatty tissue. In addition, increased levels of serum lipoproteins that are associated with increased body fat may play an anti-inflammatory role, neutralizing circulating toxins and inflammation-related proteins, Dr. Horowich says.
Obese patients also present at an earlier stage of heart failure due to increased symptoms and functional impairment, so they may be getting help sooner, which also could improve outcomes, the researchers say.