CHAT ANALYSIS OF THE INFLUENCE OF SPECIFIC RISK-FACTORS ON LATE RESULTS AFTER CAROTID ENDARTERECTOMY

The CHAT classification separates various current and historical presentations of cerebrovascular disease in an effort to determine important prognostic clues for management and prognosis. To evaluate known risk factors for late stroke and death, we followed up for an average of 44 months 633 patients who had undergone 714 carotid operations. We analyzed the indication for surgery (by CHAT) and the effect of preoperative risk factors (age, hypertension, cardiac disease., tobacco use, diabetes, hyperlipidemia, renal disease, pulmonary disease, and total risk factor score) on the end points of late stroke and death. Ipsilateral stroke was uncommon after carotid endarterectomy: with life-table analysis, the probability of late stroke at 5 years after carotid endarterectomy was 3%. Among the 127 patients with amaurosis fugax, the incidence of late stroke and of mortality was a combined total of 1% per year, and the 17 patients who had been first seen with permanent ocular stroke (blindness) fared equally well. The 28 patients who were first seen with vertebrobasilar symptoms and were treated by carotid endarterectomy also fared particularly well, with no late strokes or deaths within the first 5 years. Logistic regression analyses revealed that the various indications for carotid endarterectomy were associated with differing patterns of risk factors as significant predictors of late stroke or death. For patients first seen with asymptomatic lesions, only diabetes was an important predictor for late stroke (p = 0.05) and renal disease was the only marker for early death (p = 0.05). On the other hand, those factors were not significant risk factors for patients first seen with amaurosis fugax, for whom tobacco use was a negative predictor for stroke (p = 0.06) and male gender a negative predictor for early death (p = 0.03). After cortical transient ischemic attacks and carotid endarterectomy, there were no risk factors predictive of late stroke or of death. For patients with prior stroke, age was a very strong predictor of stroke (p = 0.0 1) and both age and a history of cardiac discase were significant risk factors for early death (p = 0.007). In contrast to the results in reports of patients treated medically for transient ischemic attacks and stroke, we found that several risk factors appeared to play relatively minor roles. In conclusion, stroke after carotid endarterectomy was uncommon, least common after ocular symptoms, and most likely after permanent cortical stroke. Specific risk factors were less important for patients after carotid endarterectomy than for the medically treated stroke patient.