By M. Mary Conroy
PHILADELPHIA (Reuters Health) - Mental impairment is a known risk following coronary bypass surgery, and now researchers have found that the procedure may hasten the emergence of Alzheimer's disease.
The results of a large study indicate that the risk of developing Alzheimer's disease within five years is 70 percent higher following coronary artery bypass grafting (CABG) than after percutaneous coronary angioplasty (PCTA). Both procedures are used to deal with restore blood flow to the heart when coronary arteries become blocked.
The researchers compared outcomes of over 5000 coronary bypass patients and nearly 4000 angioplasty patients treated at the Hines VA Hospital in Illinois. All patients were 55 or older at the start of the study and had no dementia. They were followed for five years after their procedures.
"Seventy-eight of the CABG patients and 41 of the PTCA patients were diagnosed with Alzheimer's disease during the follow-up," Dr. Benjamin Wolozin, professor of pharmacology at Boston University School of Medicine, reported here at the International Conference on Alzheimer's Disease and Related Disorders.
While this translates to a higher risk for Alzheimer's after coronary bypass than after angioplasty, Wolozin cautioned that the results should not "affect the decision to treat a patient with CABG, which is an excellent, life-saving surgery."
In an interview with Reuters Health, Dr. Martin Bednar, the lead author of the study, pointed out that the recognized mental deficits that can occur after coronary bypass are diagnosed soon after surgery. "This is the first study to report on Alzheimer's disease risk," he said.
Bednar is senior director of clinical trials at Pfizer Global Research and Development in, Groton, Connecticut. Pfizer offered partial support for the study, which was also funded by the Hines VA and Loyola University, where Wolozin worked during the study.
Wolozin said he thinks the increased risk of Alzheimer's disease is a result of stress caused by surgery that triggers an increase in stress hormones, which "may trigger a cascade of events that reduce the oxygen to the brain."
While not advising against coronary bypass, Wolozin said that some CABG patients may benefit from approaches that could reduce stress, including possibly increasing the supply of oxygen and glucose to the brain during surgery.
Bednar said Pfizer is "committed to developing neuroprotective drugs," that eventually might be used in patients undergoing CABG and other open-heart procedures.