A comparative study to assess neurocognitive functions between off pump and on pump coronary artery bypass surgery patients

Abstract

Background: Coronary artery bypass grafting (CABG) for reducing angina and stabilizing ventricular dysfunction is performed with two primary techniques: "On-pump" or "Off-pump". The present study was planned to compare neurocognitive assessment in patients undergoing "off pump" CABG and "on pump" CABG through neuropsychological tests. Materials and Methods: All consenting CABG patients meeting inclusion criteria underwent neurocognitive testing through battery of tests at baseline and 6-12 weeks after surgery. Various standardized neuropsychological tests were used to compare attention, verbal memory, visual memory and visuoconstruction ability, working memory, verbal learning, delayed recall, motor and mental speed, planning, set shifting, sustained attention, verbal fluency, category fluency and comprehension in all the groups. Results: Forty four patients underwent off-pump (OPCABG) and twenty two patients underwent on-pump (CCPB) surgery during study period. On all the neuropsychological tests in pre operative assessment both the groups were comparable except OPCABG group had significantly improved visuoconstruction ability over CCPB group (p=0.035). There was no significant difference in mean postoperative scores for the two groups in any of the neuropsychological tests. (p>0.05) Mild cognitive decline (one or two tests) was observed in 31(75.6%) of 41 OPCABG and 13(81.3%) of 16 CCPB group. A moderate or severe degree of neuropsychological dysfunction (≥3 tests) was seen in 7(17%) of 41 OPCABG, 3(18.7%) of 16 CCPB group. Conclusions: The lack of significant differences in the longitudinal test performance postoperatively between the CCPB and OPCABG group in present study suggests that the use of cardiopulmonary bypass is not the sole source of cognitive change after surgery.