Aerobic Interval Training Reduces the Burden of Atrial Fibrillation in the Short Term - A Randomised Trial

Malmo V, Nes BM, Amundsen BH, et al.
Circulation. 2016;133:466-473

Background

In patients with atrial fibrillation, exercise training is effective in treating and preventing stroke and comorbidities like hypertension, coronary artery disease, obesity, diabetes mellitus, and heart failure [1,2]. Guidelines recommend an increase of the level of physical activity in these patients, without specifying the intensity, duration and frequency of exercise [3,4]. This may be explained by the controversy regarding which level of exercise is beneficial for patients with atrial fibrillation [5]. Some relevant study results support the effectiveness of exercise training in patients with atrial fibrillation [6], while others showed that high levels of endurance exercise are associated with an increased prevalence of atrial fibrillation [7-8].
This study assessed the effect of 12 weeks of aerobic interval training (AIT) on time in AF, AF symptoms, cardiac function, exercise capacity, quality of life (QoL), lipid profile, and the need for healthcare services in patients with paroxysmal or persistent AF. 51 patients with nonpermanent AF were randomized to AIT (n=26) consisting of four 4-minute intervals at 85% to 95% of peak heart rate 3 times a week for 12 weeks or to a control group (n=25) continuing their regular exercise habits.

Main results

• Mean time in AF

   - increased from 10.4% (95% CI: 4.6–17.8)  to 14.6% (95% CI: 6.4–24.9) in the control group
   - was reduced from 8.1% (95% CI: 4.1–12.8) to 4.8% (95% CI: 2.0–7.6) in the exercise group
   with a mean difference in change between groups of 7.6 % (95% CI: 2.1–13.0, P=0.001)

•  AIT

   - reduced AF symptom frequency (P=0.006) and AF symptom severity (P=0.009)
   - improved Vo₂peak, left atrial and ventricular ejection fraction, quality-of-life measures of general health and vitality, and lipid values compared with the control group

Conclusion

Aerobic interval training for 12 weeks reduced the arrhythmic burden in patients with non-permanent atrial fibrillation, and was associated with a significant improvement in symptoms, exercise capacity, left atrial and ventricular function, lipid levels, and quality of life. Further studies are needed to assess the safety, as well as the optimal intensity and amount of exercise training in atrial fibrillation.

Editorial comment [9]

‘Until recently, the AF and exercise story has stopped here: that physically active individuals experience a small reduction in risk, but doing too much increases arrhythmia risk considerably, consistent with a classic J-shaped phenomenon. Perhaps, in part because of these findings and a misguided fear of promoting arrhythmias, there is a scarcity of data regarding the effects of exercise training in patients with nonpermanent AF’, note Elliot et al, in their editorial. This study however, represents an encouraging development for the management of atrial fibrillation that supports the increasing body of evidence according to which lifestyle modifications, including weight control and physical exercise, benefit patients with atrial fibrillation. While this study needs confirmation by trials with more participants and longer follow-up, the editors recommend: ‘We encourage clinicians to promote exercise, among other lifestyle modifications, to their patients in a bid (1) to dampen the burden of AF and its associated symptoms and (2) to decrease the heavy reliance on pharmaceutical and interventional strategies for arrhythmia management.‘

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