Risk factors for stroke after cardiac surgery: Buffalo Cardiac-Cerebral Study Group.

PURPOSE

The purpose of this study was to identify risk factors for stroke in patients undergoing heart surgery.

METHODS

A retrospective chart review of patients who underwent cardiac surgery in three hospitals of the State University of New York at Buffalo system over a 36-month period was completed. Demographics and risk factors were recorded, and stroke and death were determined by chart review. Carotid artery stenosis was determined by duplex examination. Data were analyzed by chi-squared and multiple logistic regression.

RESULTS

One thousand one hundred seventy-nine cases were analyzed, with a mortality rate of 2.3%, stroke rate of 1.6%, and combined stroke/death rate of 3.1%. Four variables were found to be associated with an increased risk of stroke: carotid artery stenosis greater than 50%, redo heart surgery, valve surgery, and prior stroke. Five variables were associated with increased mortality rates:; carotid artery stenosis greater than 50%, redo surgery, peripheral vascular disease, longer pump time, and hypercholesterolemia. Carotid artery stenosis greater than 50% was present in 14.7% of cases. Carotid artery stenosis greater than 75% was not itself associated with increased stroke risk. Most strokes occurred more than 24 hours after surgery. Stroke distribution did not correlate with site of carotid artery stenosis greater than 50%.

CONCLUSIONS

Most neurologic events after heart surgery occur in a subset of patients who can be defined before operation. Whereas carotid artery stenosis greater than 50% is a strong risk factor, the role of prophylactic endarterectomy is unclear. Future studies should focus on this high-risk subgroup. A prospective study of prophylactic carotid endarterectomy in patients undergoing coronary artery bypass grafting is needed.