LOS ANGELES -- Escaping to a warmer climate might not necessarily keep you from suffering a heart attack in the "winter months," researchers found.
An analysis of seasonal deaths in seven regions in the U.S. with very different climates found that all-cause and cardiovascular deaths during December and January remained consistently high across all regions, according to Dr. Bryan Schwartz of the University of New Mexico in Albuquerque and Dr. Robert A. Kloner of Good Samaritan Hospital in Los Angeles.
Death rates at all sites clustered closely together and no one site was statistically different from any other site, Schwartz reported here at the American Heart Association.
"We know that heart-related deaths increase in the winter months. But our research suggests there might be something other than climate at work here," Schwartz said. "If it was solely because of cold temperatures, we would have seen more deaths in Pennsylvania and Massachusetts, and we didn't see that."
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Schwartz and Kloner analyzed death certificate data from 2005 to 2008 from Texas, Arizona, Georgia, Los Angeles county, the western half of Washington state, Pennsylvania, and Massachusetts.
As expected, raw data revealed that deaths in winter were higher than those in summer, according to the peak and trough 8-day periods.
Each location had a "U" shaped curve for its average seasonal values, with peaks in winter that were 26 percent to 36 percent higher than the troughs in summer.
They also found that graphs for total deaths paralleled those for cardiovascular deaths.
"When we normalized the data for location, we found very similar patterns for circulatory death rates in between peak versus trough despite very different climates," Schwartz said.
He noted that each site had an 18% increase in deaths in winter and a 10 percent decrease in summer deaths compared with the average daily death rate.
"In the spring, deaths begin to decline, and then in the fall they begin to rise," Schwartz explained.
A discussion following Schwartz's presentation raised some interesting speculation as to why this phenomenon exists, such as decreases in vitamin D with the shorter days and less physical activity.
"No matter what climate you live in, you're more likely to die of heart-related issues in the winter," Schwartz concluded.