Author + information
- Ulf Hållmarker, MD⁎ (, )
- Karl Michaëlsson, MD, PhD,
- Johan Ärnlöv, MD, PhD and
- Stefan James, MD, PhD
- ↵⁎Mora Lasarett, Department of Internal Medicine, Department of Medical Science, Uppsala University, 792 85 Mora, Sweden
To the Editor: Physical training is generally regarded as beneficial for health. Heavy endurance exercises might, however, induce latent ischemic heart disease and acute cardiac arrhythmias. Kim et al. (1) recently reported on the incidence of cardiac arrest (CA) during long-distance running. Exercise in combination with a cold climate may be especially detrimental and trigger acute cardiac events (2). The incidence of CA during strenuous competitive exercise is uncertain. We aimed to investigate the absolute and relative risk for CA during long distance ski racing. Thus, we assessed the incidence of CA in Vasaloppet (90 km), the world's largest ski race, ongoing in Sweden since 1922, with a total of 926,350 participants through 2010. The last 10 years accounts for 45% of these skiers, with the addition of shorter distances as an option.
During 90 years of ski racing, 20 cases (mean age 55 years) of CA occurred, 5 of which survived (mean age 47 years) the acute event. All cases were men, and had support of bystander cardiopulmonary resuscitation (CPR). Coronary heart disease was the cause of CA for 16 skiers. Two had hypertrophic cardiomyopathy, 1 had myocarditis, and 1 had ventricular fibrillation of unknown cause.
The incidence proportion of CA was 2.16 per 100,000 skiers. The incidence rate was 0.31 per 100,000 skiing hours. The incidence rate was 0.46 per 100,000 racing hours in the last decade compared with 0.22 per 100,000 hours of skiing from 1922 to 2000.
The mean distance until CA occurred was 25.7 ± 15.8 km (95% confidence intervals [CI]: 6 to 45) for the survivors, and the distance for nonsurvivors was 33.6 ± 29.8 km (95% CI: 17 to 50).
The absolute risk of CA during the ski race is low. Nevertheless, the relative risk seems to be much higher than expected, considering the incidence in the race (4,030 per 100,000 person-years of skiing in the last decade) compared with the normal out-of-hospital CA rate (range, 13 to 52 by region per 100,000 person-years in recent years) in the general Swedish population (3).
The risk for CA with the vigorous physical activity was very similar to long-distance running (1.01 per 100,000 for runners) and skiing (1). However, the timing of the occurrence was different. Although CA occurred mainly during the last quarter for runners, it occurred mainly in the first third of the ski race. This may indicate different trigger mechanisms for the induction of CA in different temperatures (2).
A striking similarity between the running and the ski races was that the fatality rates were 75% and 71%, respectively, despite the 10-year higher mean age of the skiers. The possibility of survival is probably dependent of the active efforts of bystander CPR. The incidence rate in Vasaloppet has increased in the last decade, which may result from participation of less-trained people due to a greater public interest in exercise. It is important that the organizers of this kind of sporting event take responsibility for healthcare and rescue activities (4). Considering the relatively low absolute risk of CA, we are, however, convinced that the overall benefit of regular physical activity to public health is much larger than the risk of CA (5).
Please note: Dr. James has received institutional grants from AstraZeneca, Eli Lilly, BMS, Terumo Inc., Medtronic, and Vascular Solutions; and honoraria from AstraZeneca, Eli Lilly, Merck, Sanofi, and Abbott Vascular. All other author have reported that they have no relationships relevant to the contents of this paper to disclose.
- American College of Cardiology Foundation
- Bhaskaran K.,
- Hajat S.,
- Haines A.,
- Herrett E.,
- Wilkinson P.,
- Smeeth L.
- Hållmarker U.,
- Aronson D.,
- Jansson A.,
- Hamraeus K.,
- Sjögren I.