Coronary artery bypass graft (CABG) is the most common cardiac procedure performed in the United States.1 Stroke is a common complication, occurring in up to 5% of patients, especially those that are older and with known cerebrovascular disease.2 These complications can ultimately lead to poorer outcomes as well as a higher risk of mortality. For this reason, it is important to determine risk factors for these complications and possible ways to protect against it.
A 7-year study conducted at Washington University in St. Louis examined a total of 2972 patients who underwent CABG and found that a prior neurological event and atherosclerosis in the aorta predicted a stroke immediately after surgery. Those that had diabetes and atherosclerosis were also at risk of delayed stroke. Notably, women were at the greatest risk.2
Another larger study published in Annals of Thoracic Surgery examined over 16 000 patients who underwent CABG with either cardiopulmonary bypass, sternotomy, orminithorocotomy or valve repair.3 Overall, the incidence of stroke was 4.6%, with the greatest incidence occurring in patients who underwent valve surgery. Among 10 variables that were found to be independent predictors of stroke, cerebrovascular disease was most significant. Other risk factors included hypertension, diabetes, and peripheral vascular disease.
Carotid disease, especially extra-cranial carotid disease, is also a well-known risk factor for stroke, however a 5-year retrospective cohort study published in 2016 found that carotid endarterectomy prior to cardiac surgery was not beneficial, as the rate of stroke in patients undergoing the procedure was 10.34% compared to 1.43% in patients undergoing cardiac surgery with presumed or confirmed normal carotid arteries. Patients who underwent cardiac surgery with presumed normal carotid arteries had similar outcomes compared to patients with carotid disease who did not undergo carotid intervention in terms of incidence of stroke and myocardial infarction (1.43% vs 3.16%; P>.05 and 0.38% vs 1.05%; P>.05, respectively).4
A restrospective chart review conducted by Ricotta, Faggioli, Castilone et al, found a stroke rate of 1.6% in 1179 cases of cardiac surgery, with a mortality rate of 2.3%.5 Four variables were identified to be associated with an increased risk of stroke: carotid artery stenosis greater than 50%, valve surgery, history of prior stroke, and repeat cardiac surgery. Most of the strokes occurred more than 1 day postoperative. Notably, stroke distribution did not correlate with the site of carotid stenosis greater than 50%.
The 2 main causes of stroke after cardiac surgery are thought to be related to microemboli and hypoperfusion of the brain during surgery.1 Postoperative atrial fibrillation has also been linked to stroke occurrence. For this reason, it is imperative to evaluate a patient who may undergo cardiac surgery for underlying cerebrovascular disease.
- Mckhann GM, Grega MA, Borowicz LM, Baumgartner WA, Selnes OA. Stroke and encephalopathy after cardiac surgery: an update. Stroke. 2006;37(2):562-71.
- Hogue C, Murphy S, Schechtman K, Davila-Roman V. Risk factors for early or delayed stroke after cardiac surgery. Circulation. 1999;100:342-647.
- Bucerius J, Gummert J, Borger M, et al. Stroke After Cardiac Surgery: A Risk Factor Analysis of 16,184 Consecutive Adult Patients. Ann Thorac Surg. 2003;75:472–8.
- Ashrafi M, Ball S, Ali A, Zeynali I, Perricone V. Carotid endarterectomy for critical stenosis prior to cardiac surgery: Should it be done? A retrospective cohort study. Int J Surg. 2016;26:53-57.
- Ricotta JJ, Faggioli GL, Castilone A, Hassett JM. Risk factors for stroke after cardiac surgery: Buffalo Cardiac-Cerebral Study Group. J Vasc Surg. 1995;21(2):359-63.