With statistics showing that sudden cardiac death accounts for 40% of fatalities during the winter sports season, Bernhard Metzler and colleagues, from the Medical University of Innsbruck, Austria, examined the characteristics of patients admitted to the emergency department with acute MI during their winter holidays.
We felt that understanding the mechanisms that trigger AMI might help to establish preventive strategies,’ said Metzler, who noted that the study was specifically directed at foreign tourists, since this was a group in whom it was possible to define the time-point of first exposure to cold temperatures, high altitudes and exercise. Between January 2006 and April 2010 the investigators reviewed the medical histories of more than 1500 patients admitted to the University Clinic of Internal Medicine III at the Medical University of Innsbruck. Altogether 170 patients were found to have suffered an MI during their skiing holidays and they were asked to answer a retrospective questionnaire.
The patients provided information about their holidays (sea level, arrival time, planned duration and first physical activity), their medical histories, co-morbidities and training status, as well as details of the index event, including time of onset of symptoms, altitude, type of physical activity and food and alcohol intakes. If the first ischaemic symptoms occurred during physical activity or within one hour after stopping, the AMI event was classified as ‘happened during exercise’.
Results showed that:
- 56% of AMIs occurred in the first two days of physical activity
- some 70 % of the study population displayed at least two or more classical risk factors for coronary artery disease (such as smoking, diabetes and hypercholesterolemia)
- but only 19 % of patients had a known cardiac condition.
For those patients whose event ‘happened during exercise’ the mean time from the start of activity to the onset of symptoms was 1.9 hours. Furthermore, results showed that 52% of patients had performed less than two hours of sport per week before their vacation.
Altitude was also found to be a major factor, with MIs occurring at a mean height of 1350 metres above sea level; the mean altitude of the subjects‘ permanent residency was just 170 metres.
‘The fact that most of the infarcts happened in the very early phase of the vacation hints at a causal relationship between lack of preparation for the intense regime of physical exertion, exposure to high altitudes and low ambient temperatures,’ said Gert Klug, the first author of the study. He noted that each of these factors has been linked to AMI in previous studies.To lower the risk of AMI, the authors recommend that winter sports tourists should adopt a programme of exercise prior to their holidays, and then on arrival at their resort undergo stepwise increases in physical activity.