Cold weather increases the risk of heart attacks

true or false?

Looking at the medical literature, it is easy to see that winter can be a dicey season for heart patients.

Many studies have documented climbing heart attack rates during the winter. Some refer to the phenomenon as the Christmas coronary. To what extent winter raises the risk is a matter of debate. But one large study, using data on hundreds of thousands of heart attacks documented in the National Registry of Myocardial Infarction, found that 53 per cent more cases were reported in winter than in summer. A pattern of decreasing occurrence of cases from winter to fall to spring and then summer was found across gender, age and geographic area.

The primary culprit, many believe, is temperature. Cold weather narrows arteries and raises blood pressure. Physical strain and ruptured plaques caused by shoveling snow are also commonly cited.

But in a recent study presented at an American Heart Association conference, two researchers, Bryan Schwartz and Robert Kloner, found that the risk increases even in warm climates. Analysing death certificates in seven places — Los Angeles, Texas, Arizona, Pennsylvania, Massachusetts and others — they found that cardiovascular deaths rose up to 36 per cent between summer and winter, regardless of climate and temperatures.

Schwartz, of the University of New Mexico, said a number of things might be involved, including the spread of influenza and other respiratory infections. Seasonal affective disorder and less-healthy eating and exercise habits around the winter holidays may also play a role.

The verdict

Heart attack rates climb in the winter, but cold weather may be just one of several reasons.

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