(Reuters Health) - For overweight and obese people with atrial fibrillation, improving cardiorespiratory fitness with exercise may help to reduce or eliminate symptoms, a recent Australian study found.
Participants with the greatest improvements in their cardiorespiratory fitness were less burdened by symptoms of the arrhythmia and more likely to be symptom free during the study, compared to those who had smaller or no fitness improvements.
A possible side effect of the cardio exercise regimen, weight loss, may have also contributed to the improvements, researchers say.
Atrial fibrillation (AF) is a "growing epidemic" and obesity is a risk factor, the study's lead author Prash Sanders, director of the Center for Heart Rhythm Disorders at Royal Adelaide Hospital, told Reuters Health in an email.
The researchers examined the role of cardiorespiratory fitness and the incremental benefit of cardiorespiratory fitness improvement on rhythm control in 308 overweight and obese individuals with AF.
At the start of the study and four years later, participants completed questionnaires about their AF symptoms. The researchers also had patients wear a heart monitor for seven days at a time.
Based on baseline exercise stress testing, 95 people were classified as having low cardiorespiratory fitness, 134 had adequate fitness and 79 were classified as high fitness, Sanders and colleagues report in the Journal of the American College of Cardiology online June 22.
The research team prescribed the patients an exercise program tailored to their age and physical ability, which gradually increased in intensity.
By the end of four years, those who had increased their fitness levels by two metabolic equivalents (METs) or more, and those who lost weight were more likely to have reduced or no AF symptoms than those who improved by less than two METs or not at all.
Though increasing cardiorespiratory fitness seems to be beneficial, Dr. Michael Lloyd, a cardiologist at Emory University Hospital in Atlanta, Georgia, advises caution. "Overweight people should check with their doctor prior to embarking on any exercise program," said Lloyd, who was not involved in the study.
Sanders recommends a tailored exercise program, "in which consideration for age and physical ability should be made so that targets are achieved without risking injuries."
Dr. Waqas Qureshi, a cardiology researcher at Wake Forest University in Winston-Salem, North Carolina, who also was not involved in the study, noted that weight loss from exercise may add to the protection against heart irregularities.
Lloyd, however, emphasized that cardiorespiratory fitness is beneficial even apart from weight loss. "If you are overweight, it's not just the pounds that matter, it's how fit you are. This study shows that increasing your fitness through exercise and lifestyle choices does reduce your chance of having the most common arrhythmia."