Bariatric surgery tied to lower risk of weight-related atrial fibrillation

Last Updated: 2016-12-09

By Marilynn Larkin

NEW YORK (Reuters Health) - Weight loss by bariatric surgery is associated with a reduced risk of atrial fibrillation in severely obese individuals compared with usual care, researchers report.

"Obesity is a risk factor for atrial fibrillation, which in turn is associated with stroke, heart failure and increased all-cause mortality," write Dr. Kristjan Karason of Sahlgrenska University Hospital in Gothenburg, Sweden and colleagues in the Journal of the American College of Cardiology, online December 5.

To investigate whether bariatric surgery might reduce the risk of new-onset atrial fibrillation, the team analyzed medical records from the Swedish Obese Subjects study, "an ongoing controlled intervention trial that compares the effects of bariatric surgery and conventional obesity care on morbidity and mortality," Dr. Karason told Reuters Health.

The study includes patients from 25 surgical departments and 480 healthcare centers in Sweden. Patients were ages 37 to 60; men had a BMI of 34 or greater, and women, 38 or higher.

Among 4,021 obese individuals with sinus rhythm and no history of atrial fibrillation, 2,000 underwent bariatric surgery, and 2,021 matched obese control subjects received usual care.

Sixty-eight percent of those in the surgery group underwent vertical banded gastroplasty; 19%, gastric banding; and 13%, gastric bypass.

The "usual care" offered to controls "was not predefined," the authors note. "Instead, it adhered to local routines of the health centers."

During close to 20 years of follow-up, on average, 247 surgery patients (12.4%) had first-time atrial fibrillation compared with 340 (16.8%) controls. The risk of developing atrial fibrillation was 29% lower in the surgery group compared with the control group (hazard ratio, 0.71; p<0.001).

Younger patients (under 48) benefited significantly more from surgical intervention than did those who were older, as did those with a high diastolic blood pressure compared with those with a low diastolic blood pressure.

"To our knowledge, this is the first time weight-loss has been reported as reducing the risk of new-onset atrial fibrillation," Dr. Karason said by email.

"Our findings support the causal role of obesity in the development of atrial fibrillation, but relate only to men with BMI >= 34 and women with BMI >= 38," he cautioned. "Further studies are needed to show whether the results may hold for those with with lesser obesity and also to determine the degree of weight loss necessary to reduce the risk."

Dr. Jonathan Kalman of the University of Melbourne, Australia, coauthor of a related editorial comment, told Reuters Health by email, "There is now a considerable body of evidence that overweight and obese populations have a significantly increased risk of developing atrial fibrillation. There is also considerable emerging evidence that effective long-term management of patients with atrial fibrillation requires concomitant treatment of traditional cardiovascular risk factors, with weight loss forming a critical and central component of this approach."

"This study is important as it raises the role of weight loss as a primary prevention strategy for reducing the risk of developing atrial fibrillation," Dr. Kalman said. "(It was) performed in very obese individuals undergoing weight loss surgery - with quite dramatic effects - and it remains to be seen whether these results will be reproduced in less obese populations undergoing more modest nonsurgical weight loss."

SOURCE: http://bit.ly/2gjZWw1 and http://bit.ly/2hei9Zj

J Am Coll Cardiol 2016.