Afib & Obesity

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May 19, 2006 (Boston) — Higher body mass index (BMI) results in a more than

2-fold increase in the recurrence of either paroxysmal or persistent atrial

fibrillation, according to a subanalysis of the Canadian Trial of Atrial

Fibrillation (CTAF). Jean-Marc , MD, from the Montreal Heart

Institute, presented the findings here at the Heart Rhythm 2006: the 27th

Annual Scientific Sessions of the Heart Rhythm Society.

" There is increasing evidence that implicates obesity as a risk factor for

new-onset atrial fibrillation, " Dr. told meeting attendees. " But we

wanted to investigate whether BMI also modulates the risk of recurrence in

patients already diagnosed with paroxysmal or persistent atrial

fibrillation. "

The prospective, multicenter, randomized CTAF compared the effects of

amiodarone vs sotalol or propafenone for the prevention of recurrent atrial

fibrillation. For their analysis, Dr. and colleagues studied 61

patients enrolled in the CTAF study at the Montreal Heart Institute between

1996 and 1999.

The majority of these patients (62%) were men, mean age was 64.5 years, and

the average BMI was 29.5 kg/m2.

More than half (52%) of the patients had a history of hypertension, 21% had

coronary artery disease, and 15% had valvular disease at baseline.

Twenty-one percent had a left ventricular ejection fraction of less than 40%

and mean left atrial size was 43.1 mm.

Of this patient cohort, 62% were randomized to amiodarone, 28% received

propafenone, and 21% received sotalol in the overall study.

Dr. and colleagues defined the beginning of the study as 21 days

after randomization, at which time, they noted, electrical cardioversion

would have been performed as necessary. The study's primary end point was

the length of time to a first confirmed recurrence of atrial fibrillation

lasting longer than 10 minutes.

Researchers reported that 43% of patients had a recurrence of atrial

fibrillation, with a mean time to recurrence of 142 days. The patients who

had no recurrence of atrial fibrillation (57%) were followed for 425 days.

Total mean time to recurrence for all patients was 303 days.

When assessing the effects of BMI on recurrence of atrial fibrillation, Dr.

and colleagues found that patients with a BMI of more than 27

kg/m2were more likely than patients with a BMI less than 27 kg/m2

to have a recurrence of atrial fibrillation during a mean follow-up time of

14.3 months (log rank, *P* = .044). In addition, when controlling for age

and other risk factors, a BMI higher than 27 kg/m2 was an independent

predictor of recurrence of atrial fibrillation (hazard ratio, 2.8; 95%

confidence interval, 1.1 - 7.5; *P* = .03777).

" This represents a greater than 2-fold risk of recurrence when compared with

patients with a BMI less than 27, " Dr. stated.

" We had noticed that in the clinic patients with recurrent atrial

fibrillation had higher BMIs, " Dr told Medscape in an interview. " If

there is a link between recurrent atrial fibrillation and obesity, then

there is a modifiable risk factor that can be treated. " He added that sleep

apnea, diet, and autonomic tone may also be contributing factors for atrial

fibrillation in obese patients.

" We have suspected that there is a relationship between obesity and atrial

fibrillation, and this study helps confirm that, " Abraham Kocheril, MD, the

presentation moderator, commented to Medscape. " As data shows, there will be

a doubling of the obesity rates [in the United States] by 2050. We also know

that the incidence of atrial fibrillation in this country is rising and very

little has been done to address this epidemic. " Dr. Kocheril is head of

cardiac electrophysiology at the Carle Heart Center, University of Illinois

College of Medicine at Urbana-Champaign. He was not involved in the study.

" We don't really know yet if losing weight will decrease the recurrence of

atrial fibrillation. " Dr. told Medscape. " However, there are case

reports that show that patients who lose weight do have a decrease of

recurrence of atrial fibrillation, so weight loss should be a primary focus

in these patients. "

Dr. Kocheril cautioned that although weight loss is beneficial, exercise

should be moderate in patients with atrial fibrillation. " We've seen in

other studies that excessive exercise can predispose to atrial fibrillation,

so it's best to advise a middle-ground approach in these patients, " he said.

This study was independently funded. The authors report no relevant

financial relationships.

Heart Rhythm 2006: Session AB15-6. Presented May 18, 2006.