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Ann Thorac Surg 1998;66:1483-1484
© 1998 The Society of Thoracic Surgeons
a Cardiac Surgical Unit, Massachusetts General Hospital, Boston, Massachusetts, USA
Address reprint requests to Dr Akins, Department of Surgery, Massachusetts General Hospital, White 503, 55 Fruit St, Boston, MA 02114
Presented at Outcomes ’98, "The Key West Meeting," Key West, FL, May 27–31, 1998.
The most devastating nonfatal perioperative complication after coronary artery bypass grafting is a perioperative stroke, which is dreaded not only for its obvious impact on the patient but also for the increased costs of hospitalization and subsequent care, and for its deleterious impact on late survival. The problem of stroke after myocardial revascularization is a growing concern for cardiac surgeons because as the average age of the revascularization population rises, the risk of stroke rises also.
Incidence of perioperative stroke
In 1986 Gardner and colleagues [1] documented that the rising risk of stroke was a function of increasing patient age. In 1992 Tuman and associates [2] found that although the incidences of both myocardial infarction and low cardiac output were constant as patient age increased, the risk of neurologic damage rose exponentially after age 65 years. At the Massachusetts General Hospital the mean age of patients having coronary artery bypass grafting has risen from 56 years in 1980 to more than 68 years in 1997.
Causes of perioperative stroke
Clearly the causes of perioperative stroke are multifactorial, ranging from embolic debris from the heart, aorta, or cerebrovascular blood supply to low flow phenomenon on cardiopulmonary bypass and finally to intracranial hemorrhage, a surprisingly rare occurrence despite the high levels of anticoagulation on bypass. The major impact of ascending aortic atherosclerosis has been well addressed recently by Wareing and coworkers [3]. Of these issues, carotid stenosis is the one anatomic situation that can be reasonably well defined and most easily addressed surgically.
Relationship of carotid stenosis to perioperative stroke
The first attempts to relate the presence of carotid artery disease to the risk of perioperative stroke focused on carotid bruits. In 1988 Reed and colleagues [4] documented an odds ratio of 3.9 for stroke in the presence of an audible carotid bruit. Obviously carotid bruits are not reliable indicators of the degree of carotid stenosis, as verified in part of the North American Symptomatic Carotid Endarterectomy Trial [5].
Greater definition of the degree of carotid stenosis can be obtained currently with noninvasive carotid testing. Not only is the degree of carotid stenosis able to be determined, but the morphology of the carotid plaque can be evaluated. With currently available techniques some investigators have been able to document the significant deleterious impact of adding plaque ulceration to the degree of stenosis [6].
In 1990 Faggioli and colleagues [7] reported a study of noninvasive carotid screening in coronary artery bypass patients and documented the risk of stroke in patients with identified carotid stenosis that was not treated at the time of coronary artery bypass grafting. The odds ratio for stroke at the time of coronary artery bypass grafting increased 9.9-fold with an uncorrected carotid stenosis of greater than 75%. When carotid endarterectomy was performed, a lower stroke rate was achieved.
Relationship of uncorrected carotid stenosis to late stroke
Barnes and coworkers [8] in 1985 reported the late follow-up of 65 patients who had cardiovascular operations during which carotid stenosis was uncorrected. At a mean follow-up of only 22 months, 17.5% of the patients had suffered a stroke, and half of the patients had measurable progression of their carotid stenosis within 4 years.
Efficacy of carotid endarterectomy for symptomatic carotid stenosis
Two randomized trials have clearly demonstrated the advantage of surgical endarterectomy over continued medical treatment for symptomatic carotid stenosis. In the North American Symptomatic Carotid Endarterectomy Trial [9] 659 patients were evaluated. The risk of ipsilateral stroke at 2 years was 9% for the surgical patients compared with 26% for the medically treated patients. In the European Carotid Surgery Trial [10] 2,518 patients were randomized. The cumulative stroke rate at 3 years was 10.3% for the surgical patients (despite a high operative stroke rate of 7.5%) compared with 16.8% for the medical patients.
Similarly two good randomized trials have documented the efficacy of carotid endarterectomy over medical treatment for asymptomatic carotid stenosis. In 1993 the Veterans Affairs Cooperative Study [11] reported that at 4 years the combined incidence of ipsilateral neurologic events was 8.0% for surgical patients compared with 20.6% for medical patients. Also the Asymptomatic Carotid Atherosclerosis Study [12] reported in 1995 that the aggregate risk of ipsilateral stroke and any stroke or death at 5 years was 5.1% for surgical patients compared with 11.0% for medical patients.
Rationale for combined operative repair of coronary and carotid artery disease
If carotid stenosis imposes significant neurologic risks on patients at the time of coronary artery bypass operations, then the issue becomes not whether the two operations are indicated, but when they should be done. In the only randomized trial of staged and concomitant carotid endarterectomy and coronary artery bypass grafting, Hertzer and colleagues [13] randomized patients with unstable coronary syndromes and asymptomatic carotid stenoses to either combined operation or coronary revascularization followed by interval carotid endarterectomy. The incidence of stroke in the combined operations was 2.8%, which was significantly lower than the combined rate of 14% (6.9% during the coronary bypass operation and 7.5% during the late carotid endarterectomy).
Results of combined carotid and coronary operations
In 1995 my colleagues and I published our results with 200 consecutive concomitant carotid and coronary operations [14]. In patients with a mean age of 67 years the operative mortality rate was 3.5%. The total stroke rate was 4.0%, with three of the eight strokes occurring contralateral to the side of the carotid endarterectomy. At 10 years the total freedom from neurologic events, including hospital events, was 92%.
Relative cost advantage of combined operations
In 1996 Daily and coworkers [15] reported that combined operations saved a second operation and the cost of a second postoperative stay with no added operative death or stroke risk. The savings amounted to about $10,000 per patient.
Summary
The increasing risk of perioperative stroke after coronary artery bypass grafting can in part be attributed to the increased incidence of carotid stenosis with increasing patient age. The efficacy of carotid endarterectomy has been demonstrated for both symptomatic and asymptomatic patients. Combined operations yield acceptable mortality and stroke risks, provide good freedom from late events, and cost less than staged operations.
References
This article has been cited by other articles:
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  A. M. Youssuf, R. Karanam, T. Prendergast, B. Brener, S. Hertz, C. R. Saunders, and D. J. Goldstein Combined off-pump myocardial revascularization and carotid endarterectomy: early experience Ann. Thorac. Surg., November 1, 2001; 72(5): 1542 - 1545. [Abstract] [Full Text] [PDF]
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