Curt Tribble

Charlottesville, Virginia

The association of concomitant carotid bifurcation disease and significant coronary artery disease is common and presents the cardiovascular team caring for such patients with the dilemma of how to deal with both problems while minimizing the risks of treatment. There are no clear-cut answers to the many questions surrounding these issues.

The simultaneous presence of atherosclerosis in both of these vascular territories is common. It is said that the single best marker for coronary artery disease is a carotid bruit. The leading cause of short- and long-term mortality in patients undergoing carotid endarterectomy (CEA) is coronary artery disease. Also, about 20% of all patients undergoing coronary bypass grafting operations (CABG) have carotid artery obstructions of 50% or greater, and as many as 10% are thought to have obstructions greater than 80%.

Stroke is the third most common cause of death in the United States and the most common cause of disability. The most common cause of stroke is carotid bifurcation disease. Carotid endarterectomy, as an isolated procedure, can be performed by experienced surgeons with less than a 2% stroke rate under elective conditions. Several prospective trials have been conducted showing the value of prophylactic CEA in the presence of significant carotid bifurcation disease, especially if this disease is thought to have caused symptoms.

Focal neurological injury of some degree occurs in about 3% of patients undergoing coronary artery bypass surgery. While atherosclerosis of the ascending aorta is now considered to be the most common cause of these neurological injuries, it is known that the presence of carotid bifurcation disease is a marker for increased perioperative stroke risk. It is tempting to ascribe at least some of the perioperative strokes to the carotid disease, and there are some reports that support that idea. Thus, it is also attractive to consider performing CEA in conjunction with CABG in an effort to reduce perioperative stroke risk.

Unfortunately, despite the theoretical advantages of performing concomitant carotid and coronary surgery, the data supporting this strategy is mixed at best. The two primary reasons for the haziness of this data are that so many perioperative strokes do not come from the carotid disease, and the presence of disease in both territories (carotid and coronary) is associated with more diffuse vascular disease, including aortic disease, intracranial vascular disease, renovascular disease, peripheral vascular disease, aneurysmal disease and possibly more diffuse and severe coronary artery disease. Thus, patients with both coronary and carotid disease are likely to be a higher risk group from the outset. Furthermore, the factors that are well known to be associated with an increased risk of stroke associated with heart surgery are numerous, and cerebrovascular disease is just one of many harbingers of this complication. For example, in one recent study, cerebrovascular disease was just one of eleven factors that independently predicted the likelihood of perioperative stroke.

Another issue that complicates the decision making in this context is that neurological events caused by carotid disease are usually embolic and not hemodynamic. For instance, it is well known from the trauma and cancer literature that 80% to 85% of normal people can have one carotid occluded with impunity. Further complicating clear thinking about these issues is that hemodynamic parameters are used to predict these embolic events, since these parameters are the only ones we can measure with accuracy on a routine basis. Also, it is well established that there is no benefit to performing prophylactic carotid surgery prior to other major operations such as hip replacement and abdominal aortic aneurysm repair. The reason this is true seems to be that these operations do not cause an increased likelihood of carotid plaque disruption and embolization.

There are technical considerations that must be considered when trying to operate on both territories (carotid and coronary) at once, including the realities that many expert coronary surgeons are not expert peripheral vascular surgeons and that any operation is made more complicated when there is a need to coordinate two teams of surgeons not accustomed to working together. Furthermore, many aspects of carotid surgery have to be handled differently when CEA is carried out in conjunction with heart surgery, including anesthetic conditions, exposure, the use of protamine and wound management, just to mention a few of the issues that inevitably arise in trying to perform these operations concomitantly.

A metaanalysis of the available studies addressing the issue of combining carotid and coronary surgery was published recently. The authors made an attempt to include every published study that dealt with both concomitant CEA/CABG patients and patients who underwent staged operations.

This analysis revealed that the combined stroke and death rate for the concomitantly performed operations was about 10%, while the combined stroke and death rate of these operations when performed in a staged manner was about 6%. This difference reached statistical significance. An invited commentator pointed out that such an analysis is difficult to interpret because there are so many pertinent variables that are difficult to address in this kind of analysis, including the critical issues of who was performing the operation and how severe the lesions in each territory were.

Despite the difficulties of sorting through all these issues, are there specific situations in which the need for concomitant carotid and coronary surgery seem more pressing? The situations that seem to warrant increased consideration of concomitant operations include the more urgent cardiac situations, such as unstable angina, and the more ominous carotid situations, including especially carotid arteries that have been recently symptomatic, indicating the presence of potentially unstable plaque, or the presence of one completely occluded carotid artery with significant obstructive disease on the other side. Similarly, a preocclusive lesion of 85+% on either side seems also to warrant a more aggressive approach to concomitant disease.

Eventually, each cardiac team should decide for itself whether one of its members should perform the carotid surgery if the decision is made to perform concomitant CEA and CABG, or whether another team should be recruited to collaborate in the planning and execution of a combined operation.

A final consideration that may take on a growing importance will be to determine the role of carotid angioplasty in the overall strategy of dealing with this common problem. There is insufficient data with which to make recommendations at this time, though it is not difficult to foresee that decisions to utilize carotid angioplasty may occur before the patient is even referred for surgery. Trials of carotid angioplasty are now underway in the United States and, one would hope, will provide some guidance about the role of this procedure in the cardiac patient.