Risk of Arrhythmias in 52,755 Long-Distance Cross-Country Skiers: A Cohort Study

Study Questions:

Is there an association between the number of completed races and finishing time, and the risk of arrhythmias among participants of Vasaloppet, a 90 km cross-country skiing event?

Methods:

All participants without known cardiovascular disease who completed Vasaloppet, from 1989 to 1998, were followed through national registries until December 2005. The primary outcome was hospitalization for any arrhythmia; and secondary outcomes were atrial fibrillation/flutter (AF), bradyarrhythmias, other supraventricular tachycardias (SVTs), and ventricular tachycardia/ventricular fibrillation/cardiac arrest (VT/VF/CA).

Results:

Among 52,755 participants, 919 experienced arrhythmia during follow-up. Adjusting for age, education, and occupational status, those who completed the highest number of races during the period had higher risk of any arrhythmias (hazard ratio [HR],1.30; 95% confidence interval [CI], 1.08-1.58; for ≥5 vs. 1 completed race), AF (HR, 1.29; 95% CI, 1.04-1.61), and bradyarrhythmias (HR, 2.10; 95% CI, 1.28-3.47). Those who had the fastest relative finishing time also had higher risk of any arrhythmias (HR, 1.30; 95% CI, 1.04-1.62; for 100-160% vs. >240% of winning time), AF (HR, 1.20; 95% CI, 0.93-1.55), and bradyarrhythmias (HR, 1.85; 95% CI, 0.97-3.54). SVT or VT/VF/CA was not associated with finishing time or number of completed races.

Conclusions:

Among male participants of a 90 km cross-country skiing event, a faster finishing time and a high number of completed races were associated with higher risk of arrhythmias. This was mainly driven by a higher incidence of AF and bradyarrhythmias. No association with SVT or VT/VF/CA was found.

Perspective:

Increased vagal tone associated with increased aerobic fitness has been implicated as a factor predisposing to AF. This study suggests that surrogate markers for aerobic fitness (number of endurance races completed and faster finishing times) had a direct correlation with risk of arrhythmias including AF and bradyarrhythmias. To the dedicated endurance athlete, this probably is not a reason to train less or to compete at a lower level, but it provides an interesting suggestion of increased cardiac risk (albeit not a mortal cardiac risk) as a result of high-level aerobic conditioning.

Clinical Topics: Arrhythmias and Clinical EP, Sports and Exercise Cardiology, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias

Keywords: Athletes, Tachycardia, Supraventricular, Ventricular Fibrillation, Sports, Transcription Factors, Heart Arrest, Tachycardia, Ventricular, Bradycardia, Pregnancy, Prolonged, Hospitalization, Skiing, Atrial Flutter


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