Chicago, IL - Performing CABG without cardiopulmonary bypass (CPB) support, as compared with the standard "on-pump" procedure, did not lower the incidence of cognitive decline or cardiac events over five years in a randomized trial, one that confirms over the long haul what has been increasingly clear from shorter-term studies [1]. For the most part, the latest Octopus Study report suggests, late outcomes are about the same with one technique as with the other.

Previously in the trial, cognitive performance at three months seemed as if it might be better after the off-pump procedure, but even that trend had disappeared by 12 months, observe the investigators, Dr Diederik van Dijk (University Medical Center Utrecht, the Netherlands) and associates. Their current analysis, which appears in the February 21, 2007 issue of the Journal of the American Medical Association, does away with what had been a remaining question, whether the patients treated off-pump might do better in the long run.

"There may be slight differences and advantages to one type of revascularization over the other in certain cases, but overall the results are very comparable—it really depends on what kind of operation the surgeon feels like doing," Dr Frank W Sellke (Beth Israel Deaconess Medical Center, Boston, MA) told heartwire.

He said the choice of procedure might influence outcomes in only about 10% of cases. Patients with diffuse or small-vessel coronary disease or anatomy that calls for a large number of bypasses are probably better off with CPB support, according to Sellke, who was lead author of a relevant 2005 American Heart Association position statement [2] but was not involved in the Octopus Study. Also, for patients with heavily calcified aortas, some evidence suggests a lower risk of stroke or cognitive decline after off-pump procedures that don't rely on aortic clamping; clamp release, Sellke observed, can release potentially embolic debris.

Their findings don't necessarily apply to everyone undergoing CABG, especially those with higher-risk features, caution the authors. They entered only patients getting nonurgent, first-time, isolated CABG in whom an off-pump procedure was considered technically feasible. The series represented only 11% of CABG surgeries performed at the Octopus Study's three centers during the two-year recruitment period, the group writes. All surgeries in the study were performed with Medtronic's Octopus cardiac stabilizer system designed for off-pump "beating-heart" procedures.

Based on the results of standard neuropsychological tests, available at a mean of 62 months for 123 off-pump and 117 on-pump patients, the rate of cognitive decline, as defined by standard criteria, was 50.4% in both groups.

According to more restrictive—and, the authors say, more realistic—criteria that account for natural fluctuations in individual cognitive performance, the rates were 33.3% and 35.0%, respectively—also not significantly different. In this analysis, cognitive decline was independently associated with older age and lower educational level but not with sex, diabetes, peripheral vascular disease, hypertension, or number of bypass grafts.

There were no significant differences in all-cause or CV mortality or rates of stroke, MI, or repeat revascularization; the composite rate of such events; the rate of recurrent angina; or overall quality-of-life measures.

Given the similar rates of cognitive decline, the deficits may be caused by factors unrelated to CPB, "such as anesthesia and the generalized inflammatory response that is associated with major surgical procedures," write van Dijk et al. "It is also possible that the cognitive decline observed at five-year follow-up is not caused by the operation but reflects natural aging."