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Stroke during coronary bypass surgery: principal role of cerebral macroemboli
M A Borger1, J Ivanov, R D Weisel
1Division of Cardiovascular Surgery, University Health Network, and Department of Surgery, University of Toronto, Toronto General Hospital, Toronto, Ontario M5G 2C4, Canada.
Insights
Macroemboli from the ascending aorta are the main cause of stroke during coronary bypass surgery. This finding highlights the need for strategies to reduce embolization risk in cardiac procedures.
Area of Science:
- Cardiovascular Surgery
- Neurology
- Vascular Medicine
Background:
- Stroke is a serious complication following coronary bypass surgery.
- Understanding the causes of stroke is crucial for patient outcomes.
Purpose of the Study:
- To investigate the etiology of stroke in patients undergoing coronary bypass surgery.
- To identify risk factors and the primary cause of perioperative stroke.
Main Methods:
- Retrospective analysis of 6682 coronary bypass patients.
- Systematic chart review and logistic regression for stroke predictors.
- Analysis of CT scans for stroke etiology.
Main Results:
- Stroke prevalence was 1.5%, associated with increased ICU/hospital stay and mortality.
- Key predictors included age >70, low ejection fraction, prior stroke/TIA, normothermic bypass, diabetes, and peripheral vascular disease.
- Macroemboli, likely from ascending aorta atherosclerosis, were the probable cause in 37% of strokes.
Conclusions:
- Macroemboli originating from the ascending aorta are the predominant cause of stroke during coronary bypass surgery.
- Identified risk factors and etiological findings emphasize the impact of embolization.
- Future research should focus on minimizing embolization risks during cardiac surgery.
Objective:
The purpose of this study was to gain insight into the etiology of stroke during coronary bypass surgery.
Methods:
Retrospective review of prospectively gathered data on 6682 consecutive coronary bypass patients. Patients undergoing simultaneous procedures, including carotid endarterectomy, were excluded. We performed a systematic chart review of all patients who suffered a perioperative stroke. Predictors of stroke were determined with stepwise logistic regression analysis.
Results:
The prevalence of stroke was 1.5% (n=98). Stroke patients had significantly increased intensive care unit and hospital length of stays, as well as increased mortality when compared to patients without stroke (all P< 0.001). Independent predictors of stroke were (in decreasing order of magnitude): age >70 years, left ventricular ejection fraction <40%, previous stroke or transient ischemic attack, normothermic cardiopulmonary bypass, diabetes, and peripheral vascular disease. Chart review revealed that the probable cause of stroke was macroemboli, likely from ascending aorta atherosclerosis, in 37% of patients and unknown in 38% of patients. Computerized tomography (CT) scans were obtained in 79 patients (81%). Lesions detected by CT were consistent with a macroembolic etiology: nearly all lesions were ischemic in nature and located in the distribution of major cerebral arteries, particularly the middle cerebral artery.
Conclusions:
Stroke is a devastating complication of coronary bypass surgery. Our multivariable risk factors for stroke, chart review, and CT findings all suggest that macroemboli, presumably from the ascending aorta, are the predominant cause of stroke during coronary bypass surgery. Future studies should be directed at minimizing the risk of embolization during cardiac surgery.
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