Ann Thorac Surg 2001;71:781-782
© 2001 The Society of Thoracic Surgeons
Invited commentary
Norman R. Hertzer, MDa
a Department of Vascular Surgery, The Cleveland Clinic Foundation, 9500 Euclid Ave, Cleveland, OH 44195, USA
I am concerned with at least two aspects of this report because they seem to violate a couple of principles that I consider to be important in the management of patients with asymptomatic carotid stenosis. The first of these principles is based on the fact that the short-term efficacy of carotid endarterectomy (CEA) to prevent perioperative strokes in conjunction with other surgical procedures is largely intuitive. The only proven benefit of CEA is a relative reduction in the long-term stroke risk associated with truly severe (80% to 99%) carotid stenosis using the conventional duplex criteria that were cited by the authors of this article. There is no reason for the indications for prophylactic CEA to be any more liberal in coronary bypass patients than in other patients who have carotid disease alone. Several studies have shown that the incidence of unheralded stroke in patients with stable 50% to 79% or 60% to 79% stenosis of the internal carotid artery is exceedingly low (ie, about 1% per year) and does not justify CEA. Although only three of the Albany patients were symptomatic, 15 (45%) of the 33 CEAs in this series still were performed for 50% to 79% stenosis. One wonders why these 15 CEAs had to be done at all, especially in the controversial context of bilateral operations combined with coronary bypass surgery. We have considerable experience with combined operations for 80% to 99% carotid stenosis at my own center, but we routinely approve asymptomatic patients with less severe lesions for their open-heart procedures and have never regretted this policy.
The second principle that I have adopted is based on personal observations and may be regarded as anecdotal, but it is entirely consistent with the fact that a chronic reduction in perfusion pressure can interfere with the protective mechanisms that serve to autoregulate cerebral blood flow. Hyperperfusion syndrome with cerebral edema or hemorrhage is more likely to occur when bilateral CEAs for high-grade stenosis are performed without an appropriate staging interval between them. The length of time that constitutes an appropriate physiologic interval is difficult to define because it probably differs from one patient to the next, depending on the previous adequacy of other sources of collateral circulation through the circle of Willis. As a practical matter, however, it is likely to be measured in days or even weeks—not in just the few minutes separating the simultaneous bilateral CEAs in Albany. These authors have not yet encountered hyperperfusion syndrome in their 18 patients who had bilateral 80% to 99% stenosis, but it is a problem that could occur if they roll the dice often enough. At this point, however, their series simply is not large enough to draw any conclusion other than that its good results have to be interpreted pretty cautiously.
