WEDNESDAY, Sept. 18, 2002 (HealthDayNews) -- If you faint -- and the odds are you will at one time or another during your life -- tell your doctor. It could be harmless, but it also could be a warning sign of a life-threatening heart condition.
That's the message of the findings about syncope (the medical term for fainting) from the long-running Framingham Heart Study, which has followed residents of a Massachusetts town for decades.
"Other studies of syncope have been among select groups of individuals, such as Air Force recruits and those in nursing homes, not of the general population," explains Dr. Daniel Levy, medical director of the study. A report in tomorrow's New England Journal of Medicine describes an analysis of 822 fainting spells reported over 17 years by 7,814 Framingham participants.
"There has been a debate in the medical literature whether syncope carries a bad prognosis or is relatively benign," Levy says. "We tried in a relatively simple but elegant manner to get an answer."
When they sorted out the data, the researchers found that more than one-third of the fainting episodes had no known cause, while just under 10 percent had a cardiac cause. Slightly more than 20 percent had a vasovagal cause, meaning that the body's ordinary response to stress somehow went awry -- instead of increasing blood pressure and heart rate, the parasympathetic nerve system reduced blood flow enough to cause the brain to black out temporarily.
Vasovagal fainting did not put people at higher risk of death, an analysis of mortality rates showed.
But there was a substantially increased risk associated with a cardiac cause for fainting: The study found that these people were twice as likely to die from a stroke or from any cause, and 2.66 times likelier to die of heart disease. And while the numbers showed a slighter increase in mortality for fainting with no known cause, that increase was related to heart disease, often undiagnosed until then.
"When the cause of syncope is unknown, those people are at high risk, primarily from a cardiac outcome," Levy says.
"The take-home message of the study is that most episodes are benign, but they should never be ignored," says Dr. William G. Stevenson, director of the clinical cardiac electrophysiology laboratory at Brigham and Women's Hospital in Boston, and co-author of an accompanying editorial in the journal.
"Syncope should be reported to a physician and in some cases warrants a careful examination to see if there are signs of a heart problem," Stevenson says.
Going to a doctor is especially important for anyone with a known heart condition who faints, Stevenson says. "But it can also be an initial sign of a cardiovascular condition," he says.
Someone who reports several fainting episodes over a long period of time might be outfitted with a monitor to detect an abnormal heart rhythm, says Stevenson. A diagnosis can be made in about 90 percent of such cases. Most of the time the diagnosis will be reassuring, but doctors will be alert for "signs of a possibly fatal arrhythmia," he says.
What To Do
For more about fainting, consult the American Heart Association or the National Institute of Neurological Disorders and Stroke.
