Some Times/Days/Seasons
Are Riskier Than Others
For Heart Attacks
The American Heart Association
By Daniel Q. Haney
AP Medical Editor
DALLAS (AP) -- Heart attacks are more common in winter than summer. They are most likely on Mondays, even among the unemployed. And don't even think of having one at night: They're more likely to be fatal.
Heart attacks, of course, can happen any time. But several new reports released Tuesday show that some hours, days and seasons are riskier than others -- often for reasons that are not entirely clear.
Experts have been looking into these sorts of things since the mid-1980s. By far the clearest finding, now confirmed by at least 30 studies, is that morning is the riskiest time of day for the heart. Simply climbing out of bed substantially increases the danger of a heart attack, probably because it raises blood pressure, spikes stress hormones and makes the blood stickier, among other things.
All of this amounts to more than a medical curiosity.
"The better we understand how, when and where these things happen, the better we can treat them," said doctor Russell V. Luepker of the University of Minnesota.
Doctors already know that beta blocker drugs can blunt the morning peak in heart attacks. At the annual meeting of the American Heart Association in Dallas, researchers presented several new insights into how these risks fluctuate over time.
Doctor Robert A. Kloner of Good Samaritan Hospital in Los Angeles reviewed 220,000 deaths in Los Angeles between 1985 and 1996. The risk began to climb sharply around Thanksgiving, peaked at New Year's and then gradually tapered off. January turned out to be the worst month. The risk was 33 percent higher than in the summer.
"There's a theory that extreme heat or cold triggers a heart attack, but Los Angeles is relatively mild in the winter, so we were very surprised to see this difference," he said.
Kloner's theory: It's holiday stress and overindulgence, especially too much alcohol, that make this time of the year so bad for the heart.
Still, temperature may play a role in colder climates. Doctor Philippe Amouyel of Lille University in France found that the lower the temperature, the worse for the heart. For every 18 degrees Fahrenheit fall in the day's average temperature, the risk of a first heart attack increases by 13 percent.
Doctors have known for several years that heart attacks are more likely on Mondays. However, doctor Michael K. Kruska of Hanusch Hospital in Vienna found that the usual explanation -- the stress of heading back to work -- cannot account entirely for this peak.
He reviewed about 1,500 cases of fatal cardiac arrest in Vienna. About one-quarter of the victims were retired. Their risk was about 20 percent to 40 percent higher than usual on Mondays.
Kruska theorized that going shopping and resuming other stresses of the weekly routine are to blame.
While heart attacks are less common at night than during the day, another study shows they are more likely to be fatal.
Doctor C. Michael Gibson of Allegheny General Hospital in Pittsburgh looked at 1,246 heart attack victims. He found that those whose symptoms started at night were almost twice as likely to die or have a second heart attack in the hospital.
Those whose symptoms start at night take about a half hour longer to get to the hospital, but this delay does not entirely explain why late-night heart attacks are worse.
"It may have to do with differences in the way the body responds to a heart attack at night," Gibson said.