Moderate physical activity was found to reduce risk for atrial fibrillation (AF) events, according to a study published in Open Heart.

The Tromsø Study was a single-center, population-based cohort study conducted in Norway between 1994 and 2016, during which time all Tromsø inhabitants aged 25 years or older were invited to participate. Individuals who were free from known cardiac pathology were followed for AF outcomes for a median of 20.2 years. Physical activity status was defined as inactive (0 h/wk), low (0-1 h/wk), moderate (1-2 h/wk), and vigorous (³3 h/wk) activity levels.

Participants (N=2479) had a mean age of 58.6 (standard deviation [SD], 10.7) years at baseline, 52.4% were women, and BMI was 25.8 (SD, 3.8). Individuals had inactive (n=1502), low (n=383), moderate (n=391), and vigorous (n=203) physical activity statuses.


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AF events occurred among 17.9% of the inactive, 13.1% of the low, 12.3% of the moderate, and 15.8% of the vigorous physical activity cohorts. Compared with the inactive group, the moderate physical activity cohort was at decreased risk for AF events (adjusted hazard ratio [aHR], 0.68; 95% CI, 0.50-0.93; P =.017) but not the low (aHR, 0.80; 95% CI, 0.59-1.09; P =.150) or vigorous (aHR, 0.87; 95% CI, 0.60-1.27; P =.473) physical activity cohorts.

Further stratifying participants by left atrial (LA) status, found no protective effect due to physical activity among the cohort of individuals with normal LA. For the subset of individuals with enlarged LA, individuals with low physical activity were at decreased risk for AF events (aHR, 0.41; 95% CI, 0.22-0.77; P =.005), and there was a decreased trend for those with moderate physical activity (aHR, 0.62; 95% CI, 0.38-1.02; P =.061).

In a cumulative model that grouped all non-inactive physical activity cohorts together, compared with individuals who had enlarged LA and were inactive, all other individuals were at decreased risk for AF events. The lowest risk for AF events was among the enlarged LA, active cohort (aHR, 0.55; 95% CI, 0.39-0.79), followed by normal LA, active (aHR, 0.56; 95% CI, 0.42-0.75), and normal LA, inactive (aHR, 0.61; 95% CI, 0.48-0.78) groups.

Stratified by age, patterns were similar among both the younger (<65 years) and older (³65 years) participants. Stratified by sex, men were observed to have similar patterns. For women, patterns were also similar, except that those with enlarged LA, active status were not at decreased risk for AF events compared with enlarged LA, inactive status women (aHR, 0.74; 95% CI, 0.44-1.23).

This study may have been biased by evaluating LA size using an M-mode anteroposterior diameter approach, which is less accurate than biplane calculated LA volume.

“In conclusion, our prospective study of participants free from known cardiac pathology suggests a U-shaped relationship between [physical activity] and AF,” the investigators noted. “Moderate [physical activity] was associated with reduced risk [for] AF, whereas vigorous [physical activity] attenuated the protective effect of moderate [physical activity].”

Reference

Heitmann KA, Løchen M-L, Stylidis M, Hopstock LA, Schirmer H, Morseth B. Associations between physical activity, left atrial size and incident atrial fibrillation: the Tromsø Study 1994–2016. Open Heart. Published online January 24, 2022. doi:10.1136/openhrt-2021-001823