MUNICH — Long-term participation in endurance sports appears to predispose to development of lone atrial fibrillation, Luis Mont, M.D., said at the annual congress of the European Society of Cardiology.
He presented a case-control study involving 51 consecutive men who sought a cardiology consultation for lone atrial fibrillation (AF)—that is, AF in the absence of coronary disease—and 109 age-matched healthy male controls. The participants' mean age was 46 years.
Roughly two-thirds of the men in each group had been involved in organized sports at some time in their lives—primarily endurance activities. However, 31% of the men with AF were currently involved in athletics, compared with just 14% of the controls.
The risk of lone AF appeared to increase once a man exceeded about 1,500 lifetime hours of endurance sports activity, or 3 hours per week for 10 years. Men who were currently participating in endurance sports and had accumulated more than 1,500 hours of such activity in their lifetime had a 2.9-fold increased risk of having lone AF, according to Dr. Mont of the University of Barcelona, Spain.
An earlier study led by Helsinki internist Jouko Karjalainen, M.D., found that lone AF had been diagnosed in 5% of middle-aged Finnish men who were elite-level, long-time participants in orienteering—a demanding endurance sport popular in Finland—compared with just 1% of 212 male controls, and both controls with lone AF turned out to be regular vigorous exercisers.
On the other hand, the increased risk of lone AF associated with endurance exercise must be weighed against the cardiovascular benefits. The prevalence of coronary heart disease in the orienteers was only one-third that in the controls, and all-cause mortality was 1.7% in the orienteers and 8.5% in the controls, the Finnish investigators noted (BMJ 1998; 316:1784–5).