Advanced heart failure patients are considerably less likely to experience adverse outcomes if they are obese and have a higher waist circumference, according to UCLA researchers.
Approximately 5.8 million people are affected by heart failure, and around 50-66% of these patients are overweight or obese.
The study, published online in the American Journal of Cardiology, is the first to evaluate the impact of body mass index (BMI) and waist circumference on women and compare it with men.
In addition, the study provides new insight into the “obesity paradox.” Although obesity is known to increased the risk of developing cardiovascular disease and heart failure, being overweight may be beneficial once heart failure has manifested.
Dr. Tamara Horwich, an assistant professor of cardiology at the David Geffen School of Medicine at UCLA, and senior author of the study, explained:
“The study provides us with more insight about how both genders of heart failure patients may be impacted by the obesity paradox. Heart failure may prove to be one of the few health conditions where extra weight may prove to be protective.”
The team examined data on 3,187 advanced heart failure patients who received treatment at UCLA Medical Center between 1983 and 2011. According to the researchers, 2,718 patients had their BMI measured at the start of treatment and 469 patients had their waist circumference measured.
The team identified patients with a BMI higher than or equal to 25 kg/m² – this included both overweight patients (25 to 29.9 kg/m²) and obese patients (30 kg/m² or greater).
40 inches (102 cm) or greater, was considered to be a high waist circumference for men and 37 inches (88 cm) or greater was considered high for women.
At the two-year follow-up, the team found that men with a high BMI and a high waist circumference were less likely to need a heart transplant, require ventricular assist device placement and had event-free survival from adverse outcomes like death. Women also had better outcomes if their had a high BMI and high waist circumference.
According to the researchers, men with a normal BMI and waist circumference were 34% more likely to experience adverse outcomes than men with a high BMI, and women with a normal BMI and waist circumference were 38% more likely to experience worse outcomes.
Horwich said:
“We knew that obesity might provide a protective benefit for heart failure patients, but we didn’t known whether this obesity paradox applied specifically to women with heart failure, as well as men – and it does.”
First author of the study, Adrienne L. Clark, a resident in the department of medicine at the Geffen School of Medicine, explained: “The study also demonstrates how BMI and waist circumference can be used together to provide a more accurate measure of fat in the body to help determine obesity and assess risk.”
Although there are several possible explanations, the researchers are still unsure as to why the paradox exists for heart failure patients.
According to the researchers, overweight heart failure patients may benefit from increased muscle mass, as well as metabolic reserves in the form of fatty tissue. Furthermore, higher levels of serum lipoproteins that are linked to increased body fat may play an anti-inflammatory role, neutralizing circulating toxins and inflammation-related proteins.
The researchers also highlight that obese patients may seek help sooner due to increased symptoms and functional impairment caused by excess body weight.
The team highlights that larger studies with longer follow-up times are required. In addition, more research is needed to look at the physiology behind the obesity paradox.
Written by Grace Rattue