Cerebral ischemic lesions on diffusion-weighted imaging are associated with neurocognitive decline after cardiac surgery

Abstract

Background and purpose: Improvements in cardiac surgery mortality and morbidity have focused interest on the neurological injury such as stroke and cognitive decline that may accompany an otherwise successful operation. We aimed to investigate (1) the rate of stroke, new ischemic change on MRI, and cognitive impairment after cardiac valve surgery; and (2) the controversial relationship between perioperative cerebral ischemia and cognitive decline.

Methods: Forty patients (26 men; mean [SD] age 62.1 [13.7] years) undergoing intracardiac surgery (7 also with coronary artery bypass grafting) were studied. Neurological, neuropsychological, and MRI examinations were performed 24 hours before surgery and 5 days (MRI and neurology) and 6 weeks (neuropsychology and neurology) after surgery. Cognitive decline from baseline was determined using the Reliable Change Index.

Results: Two of 40 (5%) patients had perioperative strokes and 22 of 35 (63%) tested had cognitive decline in at least one measure (range, 1 to 4). Sixteen of 37 participants (43%) with postoperative imaging had new ischemic lesions (range, 1 to 17 lesions) with appearances consistent with cerebral embolization. Cognitive decline was seen in all patients with, and 35% of those without, postoperative ischemic lesions (P<0.001), and there was an association between the number of abnormal cognitive tests and ischemic burden (P<0.001).

Conclusions: We have provided a reliable estimate of the rate of stroke, postoperative ischemia, and cognitive impairment at 6 weeks after cardiac valve surgery. Cognitive impairment is associated with perioperative ischemia and is more severe with greater ischemic load.