Off-pump coronary artery bypass graft procedures, done without cardiopulmonary bypass machinery, appear to have no effect on cognitive or cardiac outcomes at five years in low-risk patients, according to an article in the February 21 issue of the Journal of the American Medical Association.

The incidence of cognitive decline in the first year after bypass graft surgery ranges from less than 5 percent to more than 30 percent. The desire to avoid the perceived negative effects of cardiopulmonary bypass has led to a renewed interest in bypass surgery on the beating heart (off-pump surgery), in part prompted by development of cardiac stabilizers, according to background information in the article. The off-pump procedure, however, is technically more demanding, and it is unknown whether off-pump surgery can match the long-term cardiac benefits of on-pump surgery or improve cognitive outcomes.

Diederik van Dijk, M.D., Ph.D., of the University Medical Center Utrecht, the Netherlands and colleagues assessed five-year cognitive and cardiac outcomes of 281 patients who were randomized to off-pump (142) or on-pump (139) surgery. After five years, 130 patients were alive in each group.

Cognitive outcomes could be determined in 123 and 117 patients in the off-pump and on-pump groups, respectively. When applying the standard definition of cognitive decline (20 percent decline in 20 percent of the main test variables), 62 (50.4 percent) of 123 patients in the off-pump group and 59 (50.4 percent) of 117 patients in the on-pump group had cognitive decline. Using a more conservative definition of cognitive decline, 41 patients in the off-pump group (33.3 percent) and 41 patients in the on-pump group (35.0 percent) had cognitive decline.

Thirty patients assigned to undergo off-pump surgery (21.1 percent) and 25 patients assigned to undergo on-pump surgery (18.0 percent) had experienced a cardiovascular event by five years’ follow-up. There were no differences between groups in the overall measure of quality of life or in angina status.

"We conclude that in low-risk patients undergoing coronary bypass graft surgery, avoiding the use of cardiopulmonary bypass had no effect on cognitive or cardiac outcome five years after the procedure," the authors wrote.

"The present results suggest that factors other than cardiopulmonary bypass may be responsible for cognitive decline, such as anesthesia and the generalized inflammatory response that is associated with major surgical procedures. It is also possible that the cognitive decline observed at five-year follow-up is not caused by the operation but reflects natural aging."