More evidence ties smoke to artery disease.

More evidence ties smoke to artery disease

Two new reports provide additional evidence of the cardiovascular risks faced by cigarette smokers and by their nonsmoking families, friends and colleagues exposed to secondhand smoke.

Regardless of the number of cigarettes smoked per day, lifelong smokers face a greater risk of clogged carotid arteries -- vessels in the neck that carry blood to the brain -- than people who quit smoking earlier in life and thus limit the duration of their smoke exposure, report researchers at the Mayo Clinic in Rochester, Minn. They say their study is the first to suggest that the number of years a person smokes cigarettes provides the most important predictor of carotid artery disease. If a blood clot blocks a carotid vessel already narrowed with fatty plaque, a debilitating or life-threatening stroke can result.

"The information about smoking that is most critical is how long a person has smoked," says study leader Jack P. Whisnant. Previous research by others focused on the number of cigarettes smoked but did not isolate duration of smoking as a separate risk factor for atherosclerosis, he says.

The Mayo team studied 752 men and women who underwent arteriography, in which physicians inject dye into the bloodstream and then take X-ray pictures of the arteries. They asked the volunteers about their smoking history, including the duration of the habit and the number of cigarettes smoked per day.

In the May STROKE, they report that 60-year-olds who had smoked for 40 years were 3.5 times more likely to show severe carotid artery disease -- in which 90 percent of the vessel is clogged -- than people of the same age who had never smoked. The Mayo researchers also found that 60-year-olds who reported smoking for 20 years were nearly twice as likely as lifelong nonsmokers to develop carotid artery disease.

A number of studies have linked cigarette smoking in men to the buildup of plaque in heart arteries, which can lead to heart attacks. Several years ago, researchers at Harvard University provided evidence that smoking posed a similar threat to women (SN: 11/28/87, p.341). Their study indicated that smokers who quit reap immediate benefits to their coronary arteries.

In carotid arteries, however, damage lingers long after smoking stops, the Mayo results suggest. People who stop puffing on cigarettes can slow the rate of new plaque buildup in these arteries but cannot reverse preexisting damage, Whisnant says.

Underscoring the dangers of inhaling others' fumes, an as-yet-unpublished review of the scientific literature shows that passive smoke exposure can cause non-smokers a number of the short-and long-term cardiovascular problems linked to smoking. Researchers described the review in Boston this week at the World Conference on Lung Health, sponsored by the American Lung Association and several other medical groups.

Stanton A. Glantz of the University of California, San Francisco, told conference participants that when nonsmokers breathe air laced with cigarette smoke, even for short periods of time, their blood platelets get sticky which can help form clots. For nonsmokers with coronary artery disease, that scenario may lead to a heart attack if a clot disrupts the heart's blood supply, Glantz notes.

In addition, Glantz says chemicals in cigarette smoke can injure the endothelium lining the coronary arteries -- the first step in the atherosclerotic process -- both in smokers and in nonsmokers who inhale others' smoke. "Passive smoking causes heart disease in otherwise healthy nonsmokers," he says. While the scientific literature doesn't reveal whether secondhand smoke exposure raises the risk of carotid artery disease and subsequent stroke, Glantz predicts that further research will establish that link.