Letter by Mont et al Regarding Article, “Physical Activity and Incidence of Atrial Fibrillation in Older Adults: The Cardiovascular Health Study”
In recent years, a number of studies have suggested an association between long-term endurance sport practice and lone atrial fibrillation (AF) in middle-aged individuals. We have read with great interest the recent study published by Mozaffarian et al1 analyzing the association of physical activity and AF in individuals >65 years of age. The results of this study seem to differ from previous observations,2–5 suggesting that physical activity is associated with lower AF incidence. How might these apparently contradictory data be explained? In our view, 2 factors could help us to understand this puzzle. First, physical activity intensity: Previous observations linking AF and exercise have focused on individuals engaged in endurance sport practice over many years. In contrast, Mozaffarian et al1 analyzed physical activity in individuals aged 65 years in the general population; therefore, most of these individuals are unlikely to have performed endurance exercise at the same intensity and duration as the long-term athletes studied previously. In fact, in this new study, only moderate-intensity physical activity showed a protective effect. Second, age: The factors associated with AF could be different at different ages. Most of the previous studies included young to middle-aged individuals, whereas in the Mozaffarian study1 only those >65 years of age were included. Moreover, as Mozaffarian et al analyzed incident AF they excluded 276 participants with prevalent AF at baseline. As a result, individuals who had performed high-endurance training and developed AF before the age of 65 years would have been excluded from analysis.
Therefore, data presented by Mozaffarian et al can be seen as complementing rather than contradicting previous observations. Although the effects of physical activity are overwhelmingly favorable, and although in individuals older than 65 years moderately intense physical activity practice seems to reduce the risk of AF, a word of caution is advisable in the context of long-term, high intensity endurance sport practice.
Mozaffarian D, Lemaitre RN, Kuller LH, Burke GL, Tracy RP, Siscovick DS. Physical activity and incidence of atrial fibrillation in older adults: the Cardiovascular Health Study. Circulation. 2008; 118: 800–807.
Karjalainen J, Kujala UM, Kaprio J, Sarna S, Viitasalo M. Lone atrial fibrillation in vigorously exercising middle aged men: case-control study. BMJ. 1998; 316: 1784–1785.
Molina L, Mont L, Marrugat J, Berruezo A, Brugada J, Bruguera J, Rebato C, Elosua R. Long-term endurance sport practice increases the incidence of lone atrial fibrillation in men: a follow-up study. Europace. 2008; 10: 618–623.
Mont L, Tamborero D, Elosua R, Molina L, Coll-Vinent B, Sitges M, Vidal B, Scalise A, Tejeira A, Berruezo A, Brugada J. Physical activity, height, and left atrial size are independent risk factors for lone atrial fibrillation in middle-aged healthy individuals. Europace. 2008; 10: 15–20.
Baldesberger S, Bauersfeld U, Candinas R, Seifert B, Zuber M, Ritter M, Jenni R, Oechslin E, Luthi P, Scharf C, Marti B, Attenhoffer Jost CH. Sinus node disease and arrhythmias in the long-term follow-up of former professional cyclists. Eur Heart J. 2008; 29: 71–78.