Preop Carotid Artery Screening and Intervention May Not Cut Stroke Risk in CABG Patients

Many institutions conduct routine carotid artery ultrasound screening of patients scheduled to undergo coronary artery bypass graft surgery (CABG) in an effort to identify carotid artery disease they believe requires intervention before or during CABG. But a newly presented review of this practice at Cleveland Clinic has yielded two notable findings:

• The results altered the management of only a minority of patients.
• Carotid endarterectomy (CEA) did not prevent perioperative stroke.

“Carotid disease might simply be a surrogate marker of diffuse atherosclerotic burden, which is known to be associated with perioperative neurological events,” says the review’s principal author, Joseph Sabik, MD, Chairman of Thoracic and Cardiovascular Surgery at Cleveland Clinic. “Hence, the value of routine preoperative carotid artery screening before coronary artery bypass surgery is questionable.”

Assessment of carotid burden

The study, presented today at the 95th Annual Meeting of the American Association for Thoracic Surgery, set out to determine how preoperative nonselective carotid artery ultrasound altered management of patients scheduled to undergo isolated CABG and to evaluate the neurologic outcomes of screened patients.

Ultrasound screenings were prospectively performed on 1,236 of 1,382 patients (89 percent) scheduled to undergo isolated CABG at Cleveland Clinic from March 2011 to September 2013. Screening results were classified by degree of coronary artery stenosis as follows:

• Mild or no stenosis (any type, 0-59 percent)
• Moderate stenosis (unilateral, 60-79 percent)
• Severe stenosis (bilateral, 60-79 percent; or unilateral, 80-100 percent)

Results: Patients’ stenosis profiles

Findings among the patients who underwent screening were as follows:

• 1,069 patients (86.5 percent) had less-than-moderate coronary artery stenosis
• 90 (7.3 percent) had moderate stenosis
• 77 (6.2 percent) had severe stenosis

Most moderate lesions were unilateral; most severe lesions were bilateral.

Of the 90 patients with moderate stenosis, four (4.4 percent) had preoperative confirmatory testing with CT angiography, yet only one patient underwent combined CABG and CEA.

Of the 77 patients with severe stenosis, 18 (23.4 percent) had preoperative confirmatory testing with CT angiography, magnetic resonance angiography or angiogram, and 18 of the 77 underwent combined CABG and CEA.

Altogether, only 13 percent of patients with moderate or severe stenosis underwent confirmatory testing, and 11 percent underwent CEA.

Results: Patient outcomes

Stroke occurred at the following rates:

• In 14 patients (1.3 percent) with less-than-moderate coronary artery stenosis
• In two patients (2.2 percent) with moderate stenosis
• In two patients (2.6 percent) with severe stenosis
• In one patient (0.7 percent) who was not screened

Of the two patients with moderate stenosis who developed stroke, neither had a history of stroke. Both underwent isolated CABG. Stroke was bilateral hemispheric in both and occurred intraoperatively in one patient and on postoperative day 4 in the other.

Of the two patients with severe stenosis who developed stroke, one had no history of stroke. This patient underwent isolated CABG and developed stroke ipsilateral to the coronary artery stenosis on postoperative day 3. The other patient, who had a history of stroke, underwent combined CABG and CEA and developed stroke contralateral to the coronary artery stenosis on postoperative day 5.

Of the 14 strokes in patients with less-than-moderate stenosis, three occurred intraoperatively and 11 occurred between postoperative days 2 and 14.

The takeaway: Consider targeted screening

The incidence of stroke was highest in patients with severe or moderate coronary artery stenosis and higher in those who underwent CEA plus CABG (5.3 percent) than in those undergoing isolated CABG (2.0 percent).

Yet stroke in the three patients with moderate or severe stenosis who underwent isolated CABG was ipsilateral to the stenosis in only one patient. “This makes the cause of perioperative stroke in the other two patients unlikely to be related to carotid disease,” notes Dr. Sabik notes.

As a result of this study, Cleveland Clinic now does targeted screening. Patients with a history of stroke, transient ischemic attack or carotid bruit still get screened, as do those with extensive vascular disease.

“We feel it is still valuable to screen high-risk patients, because it helps us in assessing risk and discussing it with the patient,” Dr. Sabik says.