High fitness reduces risk of atrial fibrillation

Two women running outdoorOverweight, hypertension, diabetes and sleep apnea increases the risk of developing atrial fibrillation (AF). Interventions aimed at these risk factors are known to reduce the risk and improve the outcome for most cardiovascular diseases. However, there has been lacking knowledge on the effect of such interventions on AF, and there has been considerable attention on the finding that large amounts of endurance exercise increases the risk of developing AF. Recent years, there have been published some studies examining this topic.

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First, a study in overweight persons (BMI ≥ 27) with AF showed that a risk management program with dietary intervention to obtain weight loss, light exercise three times a week and optimal treatment of risk factors resulted in a significant reduction on AF burden (fewer and shorter episodes), and less pronounced symptoms during AF.

The same research group examined the effect of the same program in obese persons undergoing ablation for AF. After 2 years, 90 percent of those participating in the program were free from AF or medication for AF, as opposed to only 50 percent of those not participating in the program. The effect of weight reduction over a longer period of time (5 years) has also been examined. Persons who were able to reduce their weight by at least 10 percent and keep this level had ha six-fold greater probability of being free from AF or AF medications at the last control.

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Recently it has also been published a study examining the effect of fitness on risk of developing AF in nearly 65 000 persons. This study showed that a 1 higher MET achieved during treadmill testing was associated with a 7 percent lower risk of developing AF over a 5-year period, with the largest effect in obese individuals.

Vegard Malmo. Foto: Andrea Hegdahl Tiltnes / NTNUNo studies have examined the effect of similar interventions in non-obese, and the fitness study haven’t included the most active persons. However, they provide new and important knowledge on the topic. It is still likely that high levels of endurance exercise for many years increase the risk of AF, but this is only concerning a small proportion of the population. For most people it seems that there is a graded, inverse relationship between cardiorespiratory fitness and the risk of developing AF. For persons who already have AF, it seems that changes in lifestyle and light exercise may have a very positive effect, with fewer and shorter episodes and fewer symptoms.

Vegard Malmo, PhD. Candidate at CERG

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