Risk of late stroke and survival following carotid endarterectomy procedures for symptomatic patients

Cost-effectiveness of carotid endarterectomy

Carotid endarterectomy (CEA) reduces the risk of stroke in symptomatic patients with high-grade carotid stenosis. In this study, we evaluated the long-term, societal cost-benefit ratio of endarterectomy using a decision analysis model. We reviewed the results of 150 CEAs performed at an academic center and established a Markov model comparing cohorts of patients who experienced transient ischemic attacks and then underwent observation, aspirin therapy, or CEA. The cost-effectiveness of CEA was estimated using perioperative complication rates from our review and from the North American Symptomatic Carotid Endarterectomy Trial. Stroke and mortality rates were estimated from the literature. Cost estimates were based on medicare reimbursement data. Among the 150 CEAs reviewed, complications included major stroke (0.67%), minor stroke (1.33%), myocardial infarction (1.33%), pulmonary edema (0.67%), and wound hematoma (3.33%). There were no deaths or intracerebral hemorrhages. Using complication rates from our review, CEA produced cost savings of $5730.62 over the cost of observation and $3264.66 over the cost of aspirin treatment. CEA extended the average quality-adjusted life expectancy 15.8 months over that of observation and 13.2 months over that of aspirin. Substituting the North American Symptomatic Carotid Endarterectomy Trial results, CEA yielded savings of $2997.50 over the cost of observation and $531.54 over the cost of aspirin. Quality-adjusted life expectancy was extended 13.8 months compared with observation and 11.2 months compared with aspirin therapy. This analysis demonstrates that when performed with low perioperative morbidity and mortality rates, CEA is a highly cost-effective therapy for symptomatic carotid stenosis and results in substantial societal cost and life savings.

Combined use of aspirin and heparin inhibits in vivo acute carotid thrombosis

BACKGROUND AND PURPOSE

Carotid atherosclerotic thrombosis is an important cause of ischemic stroke in Western countries. The therapeutic efficacy of either aspirin or heparin alone in this setting is still controversial. Recently we developed a simple model, the "clamp" method, to induce acute carotid mural thrombosis in vivo in guinea pigs. In this study, we used this model to evaluate the antithrombotic effects of aspirin, heparin, and their combination.

METHODS

Sixty-four male guinea pigs were divided equally into control, aspirin, heparin, and combined groups. Physiological saline, aspirin (5 mg/kg body wt), heparin (200 units/kg body wt), or a combination of aspirin and heparin, respectively, was injected via the jugular vein before the use of the clamp method. Thirty minutes after the injection of saline or drug(s), Péan's forceps was used to clamp the carotid artery at a tangent angle for 3 minutes. One hour later, the carotid artery was resected and prepared for observation under a scanning electron microscope or light microscope to evaluate the degree of mural thrombosis.

RESULTS

The results showed that the combination of aspirin and heparin had an excellent effect in inhibiting in vivo acute carotid thrombosis (p < 0.001) and was significantly better than the effect of aspirin alone (p < 0.01) or heparin alone (p < 0.01).

CONCLUSIONS

Our study clearly demonstrated that the combined use of aspirin and heparin produced a much better antithrombotic effect than either agent alone at sites of carotid endothelial injury when given before the injury. This combined regimen may be useful clinically in acute carotid thrombosis secondary to carotid diseases or carotid endarterectomy.

Perioperative stroke. Part I: General surgery, carotid artery disease, and carotid endarterectomy

Although stroke, defined as a focal neurological deficit lasting more than 24 hr, is uncommon in the perioperative period, its associated mortality and long-term disability are high. No large-scale data are available to identify the importance of recognized risk factors for stroke in the perioperative period. A review of the literature shows that the incidence and mechanism of its occurrence are influenced by the presence of cardiovascular disease and the type of surgery. The most common cause of perioperative stroke is embolism. In non-cardiac surgery, the incidence of perioperative stroke is higher among the elderly. Properly administered, controlled hypotension is associated with minimal risk of stroke. Cerebral vasospasm may be the cause of focal cerebral ischaemia in eclamptic patients, and the aggressive treatment of hypertension may exacerbate the neurological damage. The risk of stroke associated with carotid endarterectomy is closely related to the preoperative neurological presentation, and the experience of the surgical/anaesthetic team. Symptomatic cerebrovascular disease, acute stroke, asymptomatic carotid lesions, preoperative assessment of risk, local and general anaesthesia, cerebral protection and monitoring during carotid endarterectomy are discussed with reference to reducing the risk of perioperative stroke. Adequate monitoring and protection have minimized the risk of ischaemia from carotid clamping, and the major mechanism of stroke is embolization.

The carotid endarterectomy: experience with 260 cases and discussion of the indications

During 1978 to 1989, 235 patients were operated upon with 260 procedures for cervical carotid endarterectomy. The patients were classified according to the presence or absence of ischaemic symptomatology, and for symptomatic patients, according to the reversibility or persistence of ischaemic symptoms. So the selection of patients was: reversible ischaemia 46%, stroke 29%, asymptomatic patients 25%. In the stroke group, no patient was operated on as an emergency, the endarterectomy was only performed after stabilization of the clinical state. Three subgroups were included in patients operated on for asymptomatic carotid stenosis: casual discovery 40%, treatment of the second carotid artery (previous endarterectomy for symptomatic contralateral stenosis) 34%, and treatment of the second carotid artery (previous ECIC by-pass for contralateral carotid occlusion) 26%. All patients were operated upon after angiographic exploration (femoral catheterisation in most cases), and after cerebral CT scan. The surgical technique included general anaesthesia, systematic shunting, endarterectomy after longitudinal arteriotomy, closure without patch. The operating microscope has been used since 1985. The surgical results were studied in terms of uneventful postoperative course (87%), reversible complications (8%) and long lasting complications (5%). The long lasting complications were of local origin (1%), of neurological origin (2%), of general origin (1%). Overall the operative outcome at 6 months was: return to previous clinical state 95%, neurological sequelae 2%, death 3%. In the patients operated on for asymptomatic carotid stenosis the overall outcome was: previous clinical state 97%, death 3%. The legitimacy of carotid endarterectomy procedure is discussed in relation to some recent pertinent literature.

Transient ischemic attacks: an update

This is a review of extant concepts of transient ischemic attacks (TIAs), their definitions, prognostic significance, pathogenesis, physiology, and management. The natural history of TIAs depends upon the risk factors of the population group studied, so that therapeutic trials should be controlled and randomized and not dependent upon published natural history data. A strong association between TIAs and coronary artery disease has now been established. It may be difficult to establish the cause or pathogenesis of TIAs in any given patient in view of the relatively poor correlation between the patient's symptoms and location of arterial plaques. Recent studies have suggested mechanisms aside from impaired perfusion or embolization from carotid plaques or vertebral basilar disease. There are no proven indications for carotid endarterectomy, a procedure which has been excessively used in the United States, but presently ongoing prospective, randomized, controlled multi-center studies will likely resolve this important issue. Neither is there scientific validation for the use of long-term anticoagulants, but data support the efficacy of ASA in reducing the incidence of stroke and myocardial infarction in patients with TIAs.