The risk of carotid endarterectomy for the asymptomatic patient: an argument for prophylactic operation

The American Vascular Association Screening Program: Rationale, Method, Guidelines, and Progress

Introduction

The Society of Vascular Surgery, in partnership with the Society for Vascular Ultrasound (SVU), established a National Vascular Screening Program thru the American Vascular Association (AVA). The program screens for the immediate causes of stroke, abdominal aortic aneurysms (AAA), and peripheral vascular disease. Detection of these conditions while the patient still is asymptomatic allows for early management and avoidance of the devastating events they can cause.

Methods

A quick carotid scan is used for detection of carotid artery disease, an EKG rhythm strip for atrial fibrillation, blood pressure determination for hypertension, a quick abdominal scan for AAA, and ankle/brachial indices for peripheral vascular disease. The SVU position on screening, recommending credentialed technologists and accredited laboratories, is used in the AVA screening program, and reporting only the presence or absence of disease has been recommended.

Results

The AVA program, and three other programs reported, screened 6,073 seniors. It is estimated that the carotid screenings alone prevented 30 strokes and saved $12,061,400,000 in stroke costs.

Conclusion

The AVA screening program, with quality ensured by the SVU guidelines, has the potential to prevent a major number of strokes and deaths. Recommendation is for extension of the screening program and for efforts to obtain Medicare funding for the screening.

Development and implementation of a rapid, accurate, and cost-effective protocol for national stroke prevention screening

BACKGROUND

Three medical conditions--cervical carotid artery disease, atrial fibrillation, and hypertension--cause the majority of strokes. Discovering these silent, immediate causes of stroke through screening, so they can be treated before stroke occurs, can potentially prevent strokes on an epidemiologic scale.

METHODS

A rapid, accurate, and cost-effective stroke prevention screening (SPS) protocol was developed.

RESULTS

The SPS protocol was used to screen 6,073 seniors residing in the central valley of California, at Madigan Army Medical Center, at New York University, and by the American Vascular Association at 68 leading institutions. The screening was estimated to have prevented 30 strokes and to have saved the health care system >$2 million.

CONCLUSIONS

Implementation of a national SPS for seniors can discover the silent, immediate causes of strokes so they can be managed before stroke occurs and can potentially prevent the majority of strokes that we are currently not preventing.

Clinical follow-up rather than duplex surveillance after carotid endarterectomy

PURPOSE

The value of duplex surveillance and the significance of contralateral carotid disease after endarterectomy have been assessed.

METHODS

Three hundred five patients were observed prospectively after carotid endarterectomy for a median time of 36 months (range, 6 to 96 months), with duplex surveillance performed at 1 day; 1 week; 3, 6, 9, and 12 months; and then each year after endarterectomy.

RESULTS

Thirty patients (10%) had ipsilateral symptoms (13 strokes, 17 transient ischemic attacks [TIAs]) at a median time of 6 months (range, 0 to 60 months). Life table analysis demonstrated that ipsilateral stroke was equally common for patients who had > or = 50% restenosis (3% at 36 months) and those who did not (6% at 36 months, p > 0.5). Twenty-three patients (8%) developed symptoms (stroke 5, TIA 14) attributable to the contralateral carotid artery at a median time of 9 months (range, 0 to 36 months) after endarterectomy. By life table analysis, 40% of patients with 70% to 99%, 6% with 50% to 69%, 1% with < 50% contralateral internal carotid stenosis, and 5% with contralateral carotid occlusion at the time of endarterectomy had a contralateral TIA in the 36 months after endarterectomy (p < 0.01). However, contralateral stroke was not significantly more common for patients with severe contralateral internal carotid stenosis demonstrated at the time of endarterectomy (< 50% stenosis, 0%; 50% to 69%, 3%; 70% to 99%, 7%; occlusion, 6% stroke rate at 36 months). Seven of the 32 patients who developed progression of contralateral disease had a TIA, compared with 11 of 227 patients who did not develop progression of contralateral disease (p < 0.01). None of the 12 patients who progressed from a < 70% to a 70% to 99% contralateral stenosis had a stroke.

CONCLUSIONS

After carotid endarterectomy restenosis is rarely associated with symptoms; contralateral stroke is rare and is not associated with progressive internal carotid artery disease suitable for endarterectomy. This study has shown no benefit from long-term duplex surveillance after carotid endarterectomy. Selective clinical follow-up of patients who have high-grade contralateral stenoses would appear more appropriate.

Cost reduction by combined carotid endarterectomy and coronary artery bypass grafting

A significant cost reduction is likely if patients who require coronary artery bypass grafting with significant carotid stenosis have simultaneous carotid endarterectomy and bypass grafting, provided risk is not increased. To investigate this issue, we retrospectively identified cases from February 1977 to May 1994 with first-time isolated carotid endarterectomy, coronary bypass, or combined procedures. In the isolated carotid endarterectomy population, median age was 69 years and 58% (85/146) were male, as compared with 68 years and 68% (68/100) male in the combined group; median age of the coronary bypass cohort was 65 years and 76% (381/500) male. A significantly higher percentage of patients in the coronary bypass versus combined group were in New York Heart Association functional class IV. In the combined group there was a significantly higher incidence of older age, diabetes, hypertension, hyperlipidemia, renal failure, and congestive heart failure. There was no difference among the three groups with respect to hospital mortality (0%, 3.4%, and 4.0%, respectively) and permanent stroke (0.7%, 1.2%, and 0%, respectively). Hospital costs were $4,896, $10,959 and $11,089, respectively, with a savings of $4,766 (30%), and Medicare hospital reimbursement was $8,575, $23,071, and $23,071, respectively, with a savings of $10,077 (25.3%). Thus, in appropriate patients, a combined procedure is cost effective, eliminating a second surgical procedure and the cost of the postoperative stay (3.7 +/- 2.4 days) associated with isolated carotid endarterectomy. Risk of permanent stroke or death is not increased.

Efficacy of carotid endarterectomy for asymptomatic carotid stenosis. The Veterans Affairs Cooperative Study Group

BACKGROUND

The efficacy of carotid endarterectomy in patients with asymptomatic carotid stenosis has not been confirmed in randomized clinical trials, despite the widespread use of operative intervention in such patients.

METHODS

We conducted a multicenter clinical trial at 11 Veterans Affairs medical centers to determine the effect of carotid endarterectomy on the combined incidence of transient ischemic attack, transient monocular blindness, and stroke. We studied 444 men with asymptomatic carotid stenosis shown arteriographically to reduce the diameter of the arterial lumen by 50 percent or more. The patients were randomly assigned to optimal medical treatment including antiplatelet medication (aspirin) plus carotid endarterectomy (the surgical group; 211 patients) or optimal medical treatment alone (the medical group; 233 patients). All the patients at each center were followed independently by a vascular surgeon and a neurologist for a mean of 47.9 months.

RESULTS

The combined incidence of ipsilateral neurologic events was 8.0 percent in the surgical group and 20.6 percent in the medical group (P < 0.001), giving a relative risk (for the surgical group vs. the medical group) of 0.38 (95 percent confidence interval, 0.22 to 0.67). The incidence of ipsilateral stroke alone was 4.7 percent in the surgical group and 9.4 percent in the medical group. An analysis of stroke and death combined within the first 30 postoperative days showed no significant differences. Nor were there significant differences between groups in an analysis of all strokes and deaths (surgical, 41.2 percent; medical, 44.2 percent; relative risk, 0.92; 95 percent confidence interval, 0.69 to 1.22). Overall mortality, including postoperative deaths, was primarily due to coronary atherosclerosis.

CONCLUSIONS

Carotid endarterectomy reduced the overall incidence of ipsilateral neurologic events in a selected group of male patients with asymptomatic carotid stenosis. We did not find a significant influence of carotid endarterectomy on the combined incidence of stroke and death, but because of the size of our sample, a modest effect could not be excluded.

Carotid endarterectomy in the elderly

The records of 146 patients 80 years of age or older who underwent 183 carotid endarterectomy operations from 1964 through 1990 were reviewed to determine surgical risk. The indications for operation were asymptomatic patients with carotid stenosis (n = 36); ipsilateral transient ischemic attacks (n = 46); ipsilateral stroke (n = 28); ipsilateral retinal embolus (n = 15); nonlateralizing symptoms (n = 40); and asymptomatic side in patients with contralateral symptoms (n = 18). Postoperatively, three patients (1.6% of operations) had a stroke with a residual deficit and three (1.6%) died. All deaths were from myocardial infarction. For comparison, during the same time period, the combined stroke with residual deficit and death rate for patients less than 80 operated upon for similar indications was 3.5%. Since 80-year-old patients have a life expectancy of at least five years, the authors conclude that elderly patients should be evaluated for carotid endarterectomy using criteria similar to that used for younger patients.

Impact of changing attitudes in carotid surgery on community hospital practice

In 1985, institutional guidelines for the evaluation and performance of carotid surgery were established in our community hospital. During the 5-year period from 1985 through 1989, 159 carotid reconstructions were done. There were four major strokes (3%), one eventually resulting in death, with the second death in this series from a myocardial infarction (mortality 1%). The combined mortality/major stroke morbidity incidence was 3%. Three transient ischemic attacks (2%) postoperatively cleared promptly without residua. During the latter 1980s, an increasing number of vascular surgeons were doing less carotid surgery. Monitoring institutional quality assurance and individual surgeon performance within the community hospital is becoming a reality. Our experience with institutional guidelines for the evaluation and conduct of carotid surgery, together with an assessment of results and ongoing individual surgeon performance, is presented. Maintaining acceptable morbidity and mortality statistics can be enhanced by having a plan for assessment, management, and concurrent review.

The diminishing role of diagnostic arteriography in carotid artery disease: duplex scanning as definitive preoperative study

In an effort to eliminate the inherent neurologic morbidity associated with arteriographic investigation, we have increasingly relied upon duplex scans of the extracranial carotid arteries prior to endarterectomy. The percentage of patients undergoing carotid endarterectomy without arteriograms has increased from 5% in 1984 to 69% during 1988-1989. Initially, carotid endarterectomy without arteriography was limited to patients with hemispheric symptoms and relative contraindications. Over the course of the study from 1984-1989, indications for operation were similar for patients having carotid endarterectomy on the basis of duplex scan alone or following arteriography. The perioperative outcome for these patients undergoing duplex scan (n = 255) and arteriography (n = 484) were similar for stroke (2.4%) versus 2.7%, p = NS) and death (0% versus 0.4%, p = NS). Stratification of groups by indication did not show any significant differences in outcome. Duplex scans were sufficiently accurate to replace preoperative arteriograms in identifying significant stenoses at the carotid bifurcation, including asymptomatic disease. Lack of information regarding intracranial arterial occlusive disease did not adversely affect perioperative outcome. Carotid arteriography can be used selectively when duplex scans are technically difficult, when physical examination or scans suggest either inflow (arch) disease or diffuse, distal internal carotid plaque, or when cerebral symptoms are not sufficiently explained by duplex findings.