MONDAY, March 10, 2003 (HealthDayNews) -- Everyone knows that hardening of the arteries is a bad thing, a process that can lead to heart attack and stroke. Now researchers show the same is true of hardening of a heart valve.
"Hardening of the arteries" is a decidedly unscientific term for atherosclerosis, the buildup of deposits that narrow those blood vessels until a blockage causes a heart attack or stroke. There is a roughly analogous process in which deposits of calcium can build up on a heart valve, reducing its ability to control the flow of blood. Specifically, it is the mitral valve, which controls the flow of blood between the two left chambers of the heart.
An analysis of data on participants in the long-running Framingham Heart Study shows this mitral annular calcification (MAC), as it is called, increases the risk of heart ailments and stroke in direct proportion to the amount of buildup -- a 10 percent increase in risk for every millimeter of calcification.
"MAC is fairly common," says Dr. Emilia J. Benjamin, director of echocardiography and vascular testing for the Framingham study. She was the lead author of the paper reporting the finding in March 11 issue of Circulation. "We found it in 14 percent of the persons tested. This was what about we expected, because it was an elderly cohort."
Echocardiograms -- ultrasound images of the heart -- were done on 445 men and 752 women between 1979 and 1981. The men were 69 years old and women 73 years old on average. The researchers followed the participants for 16 years, during which there were 307 new cases of cardiovascular disease -- heart attack, congestive heart failure, stroke and the like -- and 213 deaths caused by heart disease.
Participants with MAC were 50 percent more likely to develop cardiovascular disease and 60 percent more likely to have died of it than those without MAC, the report says. MAC was also related to deaths from all causes.
The finding is "not surprising," says Dr. Mario J. Garcia, director of echocardiography at the Cleveland Clinic, but it does provide solid evidence to support the dangers of MAC.
"It is something that people in the field have suspected for a long time," he says. "There have been small trials that suggested this was a marker for stroke, but this study shows that it seems to indicate a higher risk of atherosclerosis in general."
MAC is a condition that is easily detected and can be treated effectively, Garcia says. "The echocardiogram is a very good tool that is used on every patient with hypertension," he says. "The thickness of the heart muscle is a marker of how well hypertension is controlled," and it also shows calcification of the mitral valve.
Once detected, MAC can be controlled and even reversed, Garcia says: "If you treat high cholesterol with drugs, you reduce the progression of calcification. It can regress if cholesterol is well controlled with drugs."
It can influence whether a patient should be prescribed lipid-lowering drugs, Garcia says, since MAC is so closely related with cholesterol levels. "Many people fall into the borderline for indications of drug therapy, such as aspirin," he says. "Having this finding on an echocardiogram can be a reason to recommend therapy."
More information
Learn about heart valve calcification from the Cleveland Clinic, while the American Heart Association has a primer on heart valves and what can go wrong with them.
