Heart Arrhythmias in Athletes
The Study: Risk of arrhythmias in 52 755 long-distance cross-country skiers: a cohort study.
The Facts:
The study looked at the association between the number of completed cross country ski races and finishing times of participants to their risk of heart arrhythmia .
52,755 athletes with no history of cardiovascular disease, all participants from the 1989 – 1998 Vasaloppet cross country ski races in Sweden, were monitored through national health care registries until 2005.
The researchers looked for any hospitalization events due to cardiac arrhythmias including atrial fibrillation, bradyarrhythmia, supraventricular tachycardia, ventricular tachycardia, ventricular fibrillation, or cardiac arrest.
The found a total of 919 participants who were hospitalized and/or treated for arrhythmia.
Participants who had completed the highest number of races during the study period were at highest risk for heart events (Hazard ratio 1.30)*
Participants with the fastest finish times were also at higher risk (Hazard Ratio 1.30)*
The highest risk appeared to be from atrial fibrillation and bradyarryhthmias.
No association was noted for Supraventricular Tachycardia, Ventricular Tachycardia, Ventricular Fibrillation, or Cardiac Arrest.
Take Home: Peak athletes (i.e. those with fastest finishing times and higher number of completed races were associated with a higher risk of arrhythmias.
Reviewer’s Comments: The authors hypothesized that ” long-term increased workload as a consequence of prolonged endurance training would lead to structural changes in the heart and autonomic disturbances, which could increase arrhythmogenicity.” This study confirms previous studies which have associated heart abnormalities with peak endurance training. Apparently more isn’t always better.
Reviewer: Mark R Payne DC
Reference: Andersen K, Farahmand B, Ahlbom A, et al. Risk of arrhythmias in 52,755 long-distance cross-country skiers: a cohort study. Eur Heart J. 2013 June 11.
*Hazard Ratio Defined: “In its simplest form the hazard ratio can be interpreted as the chance of an event occurring in the treatment arm divided by the chance of the event occurring in the control arm, or vice versa, of a study.” (From Wikipedia)
In this study, the observed hazard ratio of 1.30 indicates that athletes in these two groups (fastest finish times and greatest number of races) were at 30% greater risk (i.e. 1.3 times as likely) to be hospitalized for heart arrhythmia.