Cold Weather May Up Risk of Stroke, Severe Heart Attack for Some

But more study needed to determine what strategies might cut those risks

By Alan Mozes

Monday, August 31, 2015

MONDAY, Aug. 31, 2015 (HealthDay News) -- The onset of cold weather is clearly a bummer for beach lovers, but two new studies suggest that it may actually pose health risks for some.

One investigation, out of Taiwan, has identified a link between cold weather and a heightened risk of stroke for patients with atrial fibrillation, a common problem where the heart beats irregularly.

The finding is based on comparisons of daily temperature records in six regions of Taiwan between 2000 and 2011 and the incidence of ischemic stroke among almost 290,000 patients. Ischemic stroke, the most common type, occurs when blood flow to the brain is interrupted.

"Our study shows a clear association between temperature and risk of ischaemic stroke in patients with AF," said Dr. Tze-Fan Chao in a news release from the European Society of Cardiology. Chao is a cardiologist at Taipei Veterans General Hospital and National Yang-Ming University in Taiwan.

The concern: cold weather might promote blood clot formation in the left atrium of the heart, thereby boosting stroke risk among these patients.

The analysis revealed stroke risk rose by 10 percent in spring and nearly 20 percent in winter, as compared with summertime risk.

But the study did not prove that cold weather causes stroke risk to rise.

A second study, out of Canada, found that cold weather increased the risk for the most severe type of heart attack.

Led by researchers from the University of Manitoba in Winnipeg, that investigation found that with every 20-degree Fahrenheit drop in temperature, the risk for experiencing a very severe type of heart attack known as an ST-elevation myocardial infarction (STEMI) went up by 7 percent.

"We demonstrated that there is a clear relationship between daily temperature and the risk of STEMI," study author Dr. Shuangbo Liu, an adult cardiology resident, noted in a university news release. However, the study did not prove that drops in temperature caused heart attack risk to increase.

STEMI heart attacks, the study authors noted, usually result when plaques rupture within coronary arteries. As heart attacks go, they pose the highest risk of death.

"Daily temperature can predict STEMI risk one or two days before it happens," Liu said. "These findings create an opportunity for future research studies to examine whether there are treatment strategies that can temper the effects of climate on the risk of heart attacks."

Both Liu and Chao presented their respective findings Saturday at the European Society of Cardiology annual meeting in London. Studies presented at medical meetings are typically considered preliminary until published in a peer-reviewed medical journal.

SOURCE: European Society of Cardiology, news release, Aug. 29, 2015

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