Mechanisms of early and delayed stroke after systematic off-pump coronary artery bypass

Background/Purpose: Stroke is one of the most devastating complications after cardiac surgery. Off-pump coronary artery bypass (OPCAB) has been reported to offer a lower risk of stroke. However, limited information was available on timing and mechanisms of stroke after OPCAB. We sought to assess the incidence, timing, and mechanisms of stroke after OPCAB. Methods: A retrospective review of 1010 patients undergoing systematic OPCAB between 2001 and 2012. Stroke was defined as any focal or global neurologic deficits lasting for more than 24 hours. Stroke was classified as early stroke when it occurred less than 24 hours postoperatively, and delayed stroke when it occurred more than 24 hours postoperatively. Stroke mechanisms were classified as embolic or hypoperfusion. Results: In a total of 10 patients (1.0%) 11 episodes of stroke developed after OPCAB. Early stroke occurred in five (0.5%) patients and delayed stroke occurred in six (0.6%) patients. Of five early strokes, the mechanisms were embolic in two (40%) and hypoperfusion in three (60%). Of six delayed strokes, the mechanisms were embolic in five (83%) and unknown in one. Of six delayed strokes, all the patients had diabetes mellitus and acute cardiac events prior to surgery, and five patients had postoperative atrial fibrillation. Conclusion: The incidence of stroke after systematic OPCAB was low. Early and delayed strokes were equally distributed. Stroke mechanisms were predominantly embolic. Early and delayed stroke differed in their mechanisms. Early and delayed stroke should be considered as two separate entities and different preventive strategies should be applied in future intervention.