By Angela Gonzalez
The first study investigating the long-term effects of weight loss and the degree of weight fluctuation on atrial fibrillation (AF) burden has found that obese patients with this arrhythmia who lost at least 10% of their body weight were six times more likely to achieve long-term freedom from atrial fibrillation and maintenance of sinus rhythm than to those who did not lose weight. Avoidance of weight fluctuation was found to contribute reducing the rising burden of the disease.
The LEGACY (Long-term effect of goal directed weight management in an atrial fibrillation cohort: A long-term follow-up study) study was presented by Rajeev Pathak, cardiologist and electrophysiology fellow at the University of Adelaide, Adelaide, Australia, at a Late-breaker trial session of the American College of Cardiology’s (ACC) 64th Annual Scientific Session (14–16 March, San Diego, USA) and published simultaneously in the Journal of the American College of Cardiology.
In May 2014, at the Heart Rhythm Society Scientific Sessions, Pathak, who is the study’s lead author, presented the results of ARREST AF (Aggressive risk factor reduction study for atrial fibrillation), a study that showed a reduction in atrial fibrillation symptoms in the short term and improvement of long-term outcomes of ablation procedures in patients treated with a weight management strategy.
With the LEGACY study, Pathak and colleagues set out to investigate the effect of long-term weight loss on freedom from atrial fibrillation, the impact of weight fluctuation and the role of a dedicated weight management clinic for atrial fibrillation patients.
“We found that sustained weight loss is achievable in obese patients and that it can significantly reduce the burden of atrial fibrillation,” Pathak said. “Weight loss also led to favourable changes in cardiovascular risk factors such as high blood pressure, obstructive sleep apnoea and diabetes, along with improvements in the structure and function of the heart.”
In the LEGACY study, Pathak et al enrolled 355 obese patients (body mass index ≥27kg/m2) with symptomatic paroxysmal or persistent atrial fibrillation in a dedicated weight loss clinic (Centre for Heart Rhythm Disorders, University of Adelaide, Adelaide, Australia) and tracked their health annually for an average of four years. In order to determine the dose response effect of weight loss on atrial fibrillation burden, the researchers categorised the patients in three groups with similar baseline characteristics: patients who had 10% or greater weight loss were assigned to Group 1, in Group 2 patients with 3-9% weight loss and in Group 3 patients with <3% weight loss or weight gain. Weight fluctuation was determined by yearly follow-up.
To encourage weight loss, the clinic used a motivational, goal-directed approach that included three in-person visits per month, detailed dietary guidance, low-intensity exercise, support counseling and maintenance of a daily diet and physical activity diary.
Patients returned to the clinic annually for a health exam and atrial fibrillation monitoring. To assess the frequency, duration and severity of symptoms, patients completed questionnaires and wore a Holter monitor for seven days. Measurements of heart health including the volume of the left atrium and the thickness of the left ventricular wall were also undertaken.
After an average of four years, 45% of patients who lost 10% or more (Group 1) of their body weight and 22% of patients who lost 3 to 9% (Group 2) of their weight achieved freedom from atrial fibrillation symptoms without the use of any atrial fibrillation surgery or medication. Only 13% of patients who lost less than 3% (Group 3) of their body weight were free of symptoms without these treatments. Even with the use of surgery or medication, those who lost more weight were substantially more likely to achieve freedom from atrial fibrillation symptoms. Pathak et al note that patients with weight loss >10% resulted in a six-fold greater probability of arrhythmia-free survival compared to the other two groups.
There was a trend towards major participation from patients in Group 1 (84%) in the dedicated weight management clinic compared with patients in Group 2 (57%) and patients in Group 3 (30%). Sixty six per cent of patients in Group 1 maintained their weight loss at 34.5±15.5 months, 85% of these patients attended the weight management clinic. “These results highlight the central role of a dedicated weight management clinic in treating overweight and obese patients with atrial fibrillation,” Pathak et al note.
Sustained weight management and a linear weight loss trajectory were also associated with greater freedom from atrial fibrillation. Patients who lost and then regained weight, causing a fluctuation of more than 5% between annual visits, were twice as likely to have recurrent rhythm problems than those who did not experience such fluctuations. The researchers note that “weight fluctuation was significantly less in patients regularly attending the dedicated weight management clinic.”
Weight loss was also associated with significant beneficial structural changes in the heart and significantly improved other markers of heart health including blood pressure, cholesterol and blood sugar levels.
“Weight management is a crucial strategy for rhythm control in overweight and obese patients with atrial fibrillation,” Pathak et al concluded. They also acknowledged that “a dedicated clinic improves patient engagement by promoting treatment adherence, preventing weight regain and fluctuation.”
Commenting on future research on weight loss and atrial fibrillation Pathak told Cardiac Rhythm News: “Mechanistic studies looking at the impact of weight loss on substrate for atrial fibrillation are important. Some of these studies are underway and we are hoping to present our results soon.”