Why is a carotid (Carotid Artery) Doppler required prior to Coronary Artery Bypass Graft (CABG) surgery?

Carotid Doppler Screening Before CABG Surgery

Carotid Doppler ultrasound is recommended before CABG surgery in specific high-risk patients to identify significant carotid stenosis that may increase perioperative stroke risk, but routine screening for all CABG patients is not indicated. 1

Indications for Carotid Doppler Before CABG

Strongly Recommended (Class I)

• Patients with a recent (<6 months) history of stroke or transient ischemic attack (TIA) 1
• Patients with an audible carotid bruit on physical examination 1

Should Be Considered (Class IIa/IIb)

• Patients aged ≥70 years 1
• Patients with multivessel coronary artery disease 1
• Patients with concomitant peripheral arterial disease 1
• Patients with left main coronary stenosis 1
• History of smoking 1

Not Recommended

• Patients requiring emergency CABG with no recent history of stroke/TIA 1
• Routine screening for all CABG patients without risk factors 1, 2

Rationale for Carotid Screening

Stroke Risk in CABG

• The procedural stroke risk during or shortly after CABG is approximately 1-2% overall 1
• However, in patients with significant carotid stenosis (>80%), the risk increases substantially to approximately 9% 1
• The most common cause of CABG-related stroke is embolization of atherothrombotic debris from the ascending aorta during cannulation 1
• Only about 40% of strokes following CABG occur within the first day after surgery, while 60% occur after recovery from anesthesia 1

Risk Factors for Perioperative Stroke

• Carotid bruit (OR 3.6) 1
• Prior stroke/TIA (OR 3.6) 1
• Severe carotid stenosis (OR 4.3) 1
• Age, smaller body surface area, emergency surgery, pre-operative atrial fibrillation, and on-pump CABG with hypothermic circulatory arrest 1

Limitations of Carotid Screening

• 50% of patients suffering strokes after CABG do not have significant carotid artery disease 1
• 60% of territorial infarctions on CT scan/autopsy cannot be attributed to carotid disease alone 1
• Routine carotid Doppler ultrasound identifies only a minority of patients who will develop perioperative stroke 1
• There is limited evidence that prophylactic carotid revascularization significantly reduces stroke risk in asymptomatic patients 2

Management of Identified Carotid Stenosis

For Symptomatic Patients (with recent TIA/stroke)

• Carotid revascularization should be considered in patients with 50-99% carotid stenosis 1
• Carotid endarterectomy (CEA) should be considered as first choice in these patients 1

For Asymptomatic Patients

• Routine prophylactic carotid revascularization in patients with unilateral 70-99% carotid stenosis is not recommended 1, 3
• Carotid revascularization may be considered in specific high-risk scenarios:
  • Bilateral 70-99% carotid stenosis 1
  • Unilateral 70-99% stenosis with contralateral occlusion 1, 3
  • Evidence of ipsilateral silent cerebral infarction 1

Clinical Approach

• Targeted screening based on risk factors can identify most patients with significant carotid stenosis while reducing unnecessary testing by approximately 40% 1
• When significant carotid stenosis is identified, management decisions should involve a multidisciplinary team including a neurologist 1
• The timing of procedures (synchronous or staged) should be determined based on clinical presentation and local expertise, targeting the most symptomatic territory first 1

Caution

• The presence of carotid stenosis may be a marker of generalized atherosclerosis rather than a direct cause of perioperative stroke in many cases 3, 2
• The benefit of prophylactic carotid intervention in asymptomatic patients remains controversial with limited evidence of improved outcomes 3
• Combined or staged carotid and coronary procedures carry their own risks that must be weighed against potential benefits 4