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Cleveland Clinic Study Examines Stroke Risk Associated With Coronary Artery Bypass Grafting

Operative Strategies Show Possible Ways to Decrease Risk of Stroke

January 25, 2011

The risk of stroke associated with coronary artery bypass graft (CABG) surgery may be influenced by operative strategies, according to a new Cleveland Clinic study being published in the Journal of the American Medical Association (JAMA).

The study closely examined the occurrence of stroke in 45,432 patients who had undergone CABG surgery at the Cleveland Clinic from 1982 to 2010. Among the patients in the study, 705 experienced a stroke (1.6 percent); of those, 279 (40 percent) occurred during surgery and 409 (58 percent) occurred in the hospital post-surgery.

The study analyzed how four different operative strategies to perform CABG may have affected the risk of stroke: cardiopulmonary bypass (“on pump”) with the heart stopped, which is the way most CABG surgery is done; on-pump with the heart still beating; on-pump with low-temperature circulatory arrest; and no assistance from a pump (“off-pump” CABG).

Lowest stroke risk was observed when the surgery was performed without the assistance of the pump (0.5 percent) or on-pump with the heart still beating (0%). The highest risk of stroke was observed when the pump was used with low-temperature circulatory arrest (5.3 percent), a strategy (along with on-pump with the heart still beating) often used when severe arteriosclerotic plaques in the aorta could be dislodged.

“On-pump arrested CABG surgery is a standard operating procedure that is used in many hospitals throughout the country, while off-pump CABG is used by a smaller population of surgeons,” said Joseph Sabik, MD, Chairman, Cleveland Clinic’s Department of Thoracic and Cardiovascular Surgery and a contributing author of the JAMA study. “This study should encourage taking a closer look at which approach to CABG surgery is the best for the patient, particularly the patient who is elderly or who has a diseased aorta.”

Additional stroke risk factors that are common to both pre- and post-surgery strokes include: older age, smaller body size, previous stoke and atrial fibrillation. In addition to surgical techniques, other stroke risk factors that occur during surgery include arterial disease, previous cardiac operations, poor health going into surgery and left ventricular dysfunction. Patients in the study who experienced a stroke were found to have worse hospital outcomes and disabling complications.

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Cleveland Clinic, located in Cleveland, Ohio, is a not-for-profit multispecialty academic medical center that integrates clinical and hospital care with research and education. It was founded in 1921 by four renowned physicians with a vision of providing outstanding patient care based upon the principles of cooperation, compassion and innovation. U.S. News & World Report consistently names Cleveland Clinic as one of the nation’s best hospitals in its annual “America’s Best Hospitals” survey. About 2,100 full-time salaried physicians and researchers and 11,000 nurses represent 120 medical specialties and subspecialties. In addition to its main campus, Cleveland Clinic operates nine regional hospitals and 15 Family Health Centers in Northeast Ohio, Cleveland Clinic Florida, the Lou Ruvo Center for Brain Health in Las Vegas, Cleveland Clinic Canada, and opening in 2012, Cleveland Clinic Abu Dhabi. In 2009, there were more than 4.6 million visits throughout the Cleveland Clinic health system and 170,000 hospital admissions. Patients came for treatment from every state and from more than 100 countries. Visit us at

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