A recent Australian study shows that overweight or obese patients with atrial fibrillation, or irregular heart rhythm, can experience improvement in their condition by getting fit. Improved cardiovascular fitness with exercise was shown to alleviate symptoms, and participants with the greatest fitness gains were more likely to survive symptom-free during the study, in contrast to those with smaller or no improvements in fitness.
Weight loss was a side effect for some participants, and researchers say that may have been a contributing factor. Lead author Prash Sanders, director of the Center for Heart Rhythm Disorders at Royal Adelaide Hospital, says obesity is a risk factor for atrial fibrillation, which he described as “a growing epidemic.”
Atrial fibrillation is characterized by rapid irregular heatbeats, causing the formation of clots and impeding blood flow. A-Fib, or AF, affects over 33 million people around the world, the researchers write in the Journal of the American College of Cardiology, which published the study.
The researchers knew weight loss has been shown to help improve heart rhythm issues, but they wanted to learn how improved cardiovascular fitness might benefit overweight patients afflicted with the condition. 308 overweight and obese participants with atrial fibrillation completed questionnaires at the beginning of the study and then, four years later, at the conclusion. They reported on the frequency of heartbeat irregularities, and the length and severity of the episodes.
Patients also wore a heart monitor for seven days at a time.
Through exercise stress tests administered at the beginning of the study, 95 participants were classified as having low cardiovascular fitness. 134 had adequate fitness, and 79 were considered to have high fitness levels. Researchers assessed the amount of exercise effort these participants could manage, in terms of units called Metabolic Equivalent of Task (MET). Jogging is equivalent to seven METS, and walking equals about three METS.
The team prescribed each patient an exercise program designed for them specifically, based on their age and physical ability. The program gradually increased in intensity.
At the end of the four-year study, participants who had increased their fitness levels by two METs or more, and participants who had lost weight, were more likely to have reduced or no symptoms of irregular heatbeat than those who improved by less than two METs, or did not improve at all.