STUDY LINKS BYPASSES, BRAIN DAMAGE.

Byline: Lawrence K. Altman The New York Times

Heart bypass surgery leads to serious physical and mental impairment from strokes and other brain damage more often than many experts had previously believed, a large study has found.

Six percent, or 129, of the more than 2,100 participants suffered new and severe neurological complications, including stroke or substantial deterioration of memory, concentration or other intellectual function similar to Alzheimer's disease. Of these, eight participants died from strokes.

Survivors stayed in the hospital longer after heart surgery and needed extensive use of costly rehabilitation and other health care facilities.

Although it has long been known that some people have trouble thinking and remembering clearly while recovering from bypass surgery, most surgeons have asserted that such patients eventually regain their mental agility.

But the study by a team of researchers headed by Dr. Dennis Mangano, an anesthesiologist at the University of California, San Francisco, suggested otherwise. It is being published today in The New England Journal of Medicine.

Mangano said that drugs and other methods were needed to help reduce the incidence of such adverse effects, which may be permanent in many cases. Many medical centers are beginning more routine use of new techniques to reduce the incidence of such complications, Mangano and Dr. O. Wayne Isom, the head of heart surgery at New York Hospital-Cornell Medical Center, said in interviews.

About 300,000 heart bypass operations are performed in this country each year, and the number of such procedures is expected to rise substantially as more people live longer. Fewer bypasses are performed in other countries but the number is increasing. In such operations, blood vessels from elsewhere in the body are used as grafts to restore blood flow by bypassing coronary arteries that have been narrowed by the fatty deposits of atherosclerosis.

Mangano's study included at least 100 patients from each of 24 hospitals that are considered among the leading heart surgery centers in the United States. The 24 centers perform about 10 percent of all such surgeries performed in this country, Mangano said.

In the interview, Mangano said he believed that the study was the first to follow neurological complications among people who electively underwent bypass surgery.

In the article, the authors said that most earlier studies of the neurological complications of heart bypass surgery were performed at a single hospital, involved fewer patients, and led to a wide variation in findings. For example, Mangano's team said the incidence of stroke after bypass surgery was as low as 0.5 percent in earlier research and the incidence of brain and psychological dysfunction noted before bypass patients left the hospital ranged from 25 percent to 79 percent.

The study enrolled 2,417 participants from September 1991 to September 1993, and followed them until September 1995.