Coronary Artery Bypass Grafting: The Usefulness of Neurological Screening

Objective: There is a risk of stroke in patients undergoing coronary artery bypass surgery (CABG) and coincidence of high-grade carotid artery stenosis in ∼6–8% of patients is described. Therefore a preoperative carotid ultrasound is required as a screening tool - but is it a valuable predictor for neurological outcome?

Methods: All elective patients (1173 pat.) receiving CABG at our center in 2013 and 2014 were evaluated retrospectively. Patients' characteristics, operative procedure and early postoperative results were analyzed in the EQS-database and medical records. Carotid artery stenoses were classified by NASCET (North American Symptomatic Carotid Endarterectomy Trial), a stenosis >80% was defined as severe.

Results: 88.8% of patients were screened preoperatively using carotid ultrasound. Carotid artery stenosis >80% NASCET was found in 4.9% (57 pat.). A total of 13 patients received synchronous CABG and carotid endarterectomy. The other 44 patients with severe stenosis did not receive any treatment of carotid stenosis at time of CABG. The percentage of off-pump versus on-pump procedures was significantly higher in patients with severe ACI stenosis (64.9% (ACI > 80%) versus 44.3% (others), p< 0.05). Other characteristics as amount of bypass grafts, graft material, duration of hospital stay or inner hospital mortality were equal in both groups (p = n.s). Postoperatively 8.8% of patients with severe ACI stenosis compared with 4.4% of others requested a neurological follow up (p< 0.05). Perioperative stroke was detected in 14 patients (1.3%) with a significantly higher amount of strokes in patients with severe ACI stenosis (7.1% (ACI > 80%) versus 1.1% (others), p< 0.005). Following CABG 8.8% of pat. with ACI >80% versus 3.5% of other pat. received further imaging (p< 0.005). Pathological cCT/ cMRT findings were shown in 80% of pat. with ACI >80% and in 35.9% of other pat. (p< 0.005).

Conclusion: Preoperative screening with carotid ultrasound is still requested, nevertheless it cannot be used as a direct predictor for neurological outcome. A unified and standardised approach of patients with high-grade carotid stenosis should be established, including standardised imaging, documentation and choice of operating procedure.