Novice mountaineers may lower their risk of having a fatal heart attack if they acclimate themselves before a high-altitude recreational hiking or skiing expedition, according to a study published in the American Heart Journal.
The study found the risk of dying of (sudden cardiac death) on the first day of vigorous mountain exercise was more than five times as high in individuals who had slept at lower elevations on the previous evening as in those who slept at higher elevations.
A short period of acclimatization beforehand could significantly reduce the risk of sudden death, especially in men over age 34, beginner mountaineers, or those with a history of heart problems, the study says.
Researchers in Dallas analyzed 301 sudden cardiac deaths that occurred during weeklong expeditions in the Austrian mountains from 1985 to 1993. The data was collected from questionnaires and interviews with relatives. On average, the victims were 58 to 60 years of age and slightly overweight. Just over 40% had high cholesterol and high blood pressure, 26% had suffered a previous heart attack and about 25% smoked.
Of the 301 victims, 149 died on the first day and 152 died on a subsequent day; 29% of the deaths occurred around noon after 2½ hours of activity. Almost two-thirds, 59%, died hiking on relatively easy terrain, while 39% were cross-country, downhill or backcountry skiing.
Sleeping altitude was the only significant predictor of sudden cardiac death on the first day, the analysis found. Those individuals who died on the first day slept at an altitude about 1,000 feet lower than those who died on a subsequent day. Deaths in both groups occurred at altitudes of 5,354 to 5,899 feet.
Spending the first night at a higher altitude may have resulted in some degree of acclimatization by reducing the effects of myocardial ischemia, or reduced blood flow to heart tissue, and other triggers of sudden cardiac death, the researchers said.
American Heart Journal article...