53. Combined Carotid and Coronary Artery Surgery- Review of CT Surgery

Amir A. Sarkshik and Victor Rodriguez

This chapter is a revision and update of that included in previous editions of the TSRA Review written by Lawrence E Greiten (2^nd edition) and Stephen H McKellar (1^st edition).

Epidemiology and Incidence

Perioperative stroke remains of the most devastating complications of CABG, contributing to significant short- and long-term mortality. A review of >1.5 million isolated CABG patients from the STS Database has quoted the incidence to be around 1.3%. While this may be low, the perioperative mortality associated with these patients is close to 20%. Major risk factors include age ≥65, history of prior stroke, renal failure, diabetes, hypertension and female sex. Cardioembolic events from manipulation and instrumentation of the aorta account for about 75% of events while carotid artery stenosis accounts for roughly 5% of cases. The association between extracranial carotid artery stenosis (ECAS) and coronary artery disease (CAD) is well-recognized given their mirrored pathogenesis. Approximately 8% of those undergoing CABG have been found to possess severe ECAS (stenosis ≥70%), which is an independent risk-factor for perioperative stroke. As illustrated below, the severity of CAD and ECAS are closely associated with left-main disease serving a key role for identifying concomitant ECAS. Finally, there is an increased level of perioperative strokes in those with severe ECAS—and whether carotid disease is the source or just serves as a surrogate for its etiology remains debated.

CAD Severity	ECAS (≥70%)
1-Vessel	5%
2-Vessel	13%
3-Vessel	25%
Left main	40%

ECAS Severity	Stroke Risk in ♂ >65
Stenosis < 50%	1.5%
Unilateral 50% – 99%	3%
Bilateral 50% – 99%	5%
Occluded carotid a.	11%

Decision to Screen

While ECAS accounts for a minority of perioperative strokes, it represents a modifiable factor subject to therapy by the operating surgeon. The ACC/AHA guidelines have defined key features to risk-stratify patients for better screening. Having ≥1 these features has been found to correspond with significant carotid disease, justifying preoperative screening.

An isolated carotid bruit, in the absence of other risk-factors, should not prompt a carotid duplex ultrasound. The Northern Manhattan Stroke Study underscored the low positive predictive value and sensitivity of carotid auscultation for stenosis. As part of the Choosing Wisely Campaign, the STS now recommends against screening low-risk, neurologically asymptomatic patients with carotid bruit on exam.

Screening Modality

While carotid duplex ultrasound scanning (CDUS) serves as an excellent screening tool, its inherent limitations must be recognized to circumvent any erroneous conclusions. Given its dependence on flow velocity, studies can give the false impression of an observed or over-estimated degree of stenosis. For instance, in patients with contralateral occlusive disease a false elevation of velocities in the in the ipsilateral artery of interest is often encountered. As such, when needed, CTA vs. MRA should be performed for a more accurate depiction.

Decision to Treat

To date, the optimal management of patients with co-existing conditions has not been well delineated. In the absence of a randomized trial, society guidelines currently draw from retrospective, institutional experiences for their recommendations. The presence of symptomatic ECAS is universally accepted as a major risk-factor, making the decision to treat more straightforward. Having said that over 90% of those who ultimately undergo concomitant CABG + CEA are reported to be asymptomatic from their carotid disease. This is justified due to the well-recognized, well-studied, late protective benefits of carotid revascularization in asymptomatic, severe carotid profiles. In one paper, Ascher et al. revealed a x10-fold increase in the rate of stroke (10%) at 48-months in those with an uncorrected [asymptomatic] severe carotid disease at the time of CABG when compared to those who underwent a concomitant CEA. Other studies have shown the accumulative benefit of carotid re-vascularization to amount to a risk-reduction of 1% per annum.

In patients with asymptomatic, unilateral ECAS, the perioperative risk of stroke when undergoing a CABG alone is approximately 2% — slightly higher than that of the general population. Interestingly, the stroke rate for those undergoing CEA for asymptomatic, unilateral ECAS is quoted around 2.5%. This lends credence to the theory that carotid disease is a surrogate for immediate neurologic complications, which makes the intent to treat pivot on the added protective benefits that extend beyond the perioperative period. Current guidelines favor concomitant carotid re-vascularization with CABG in patients who have a prior history of stroke or TIA in the setting of significant ECAS (≥50% in men and ≥70% in women). In asymptomatic patients, concomitant should be done in patients with bilateral ≥50% carotid stenoses and in those with unilateral ≥50% stenosis and contralateral occlusion.

Timing and Type of Re-Vascularization

In general, the sequence and timing of therapies should be determined by the severity of worst disease. In patients with unstable angina and asymptomatic carotid disease — priority must be given to coronary revascularization. Conversely, in those with stable CAD that present with symptomatic carotid stenosis or are asymptomatic but found to have bilateral stenoses ≥50%, unilateral stenosis ≥50% with contralateral occlusion, concomitant revascularization must be considered. Treatment options for the management of co-existing disease are defined below.

Carotid artery stenting has become more popular in recent years after the SAFFIRE and CREST trials revealed non-inferiority to CEA with comparable adverse events. In the absence of a randomized study comparing the two in CABG patients, choice for re-vascularization will depend on patient characteristics, operator comfort, and institutional expertise.

Special considerations must be taken when deciding on the choice for therapy as the method, sequence and timing can be inextricably linked. For instance, CAS patients will need to be placed on dual anti-platelet therapy for a circumscribed period. This has been shown to contribute to a 4-fold increase in the bleeding risk of those slated to undergo an urgent CABG. Subsequently, in those who require concomitant therapy, CEA is generally the advised choice for revascularization. CAS can be considered in elective, reverse staged cases.

While currently there is no consensus on the subject, approximate agreement on the management of patients with co-existing disease is illustrated below.

Decision to Treat

Suggested Readings