Table 4 presents the results of a univariate analysis of patient demographics and comorbidities, comparing patients who developed postoperative MI, stroke, and death with those who did not. Significant differences were associated with history of transient ischemic attack (TIA), symptomatic status, preoperative functional status (mRS), and statin use. Of 481 patients with a history of TIA, 18 (3.74%) developed postoperative MI, stroke, or death (P=0.045). Of 758 symptomatic patients, 30 (3.96%) developed postoperative MI, stroke, or death (P=0.001). Of 110 patients who had mRS ≥3, nine (8.18%) developed postoperative MI, stroke, or death (P <0.001). Of 1224 patients who were treated with statins preoperatively, 24 (1.96%) developed postoperative MI, stroke, or death (P=0.017).
Multivariate Logistic regression was carried out to determine preoperative risk factors for MI, stroke, and death (Table 5). The presence of symptoms (OR=2.485; 95% CI=1.267-4.876; P=0.008), history of TIA (OR=1.964; 95% CI=1.046-3.689; P=0.036), and mRS ≥3 (OR=3.025; 95% CI=1.353-6.763; P=0.007) were independent risk factors for postoperative MI, stroke, and death. In addition, statin use before surgery was an independent protective factor (OR=0.524; 95% CI=0.279-0.983; P=0.044).
The efficacy and safety of CEA in the treatment of carotid artery stenosis have been confirmed.2,3,12 However, some carotid artery stenosis patients cannot receive CEA treatment due to operation risks and lesion localization. Generally, CAS offers the advantage of being minimally invasive. Based on the SAPPHIRE results, in 2004, the US Food and Drug Administration approved the first CAS for use in the United States for the treatment of extracranial carotid artery stenosis in patients at high risk for adverse events from CEA. CAS has been performed in increasing numbers, and many randomized trials (e.g., SAPPHIRE, EVA-3S, SPACE, and CREST) comparing CEA and CAS have been completed in order to determine their relative effectiveness and safety.9,10,13–15 CAS may be superior to CEA in certain patient groups, such as those who have had previous neck surgery or radiation injury. Recently, the CREST study reported that there were no significant differences between CAS versus CEA by symptom status for the periprocedural MI, stroke, and death rates.9 Therefore, CAS is effective and safe in the treatment of carotid artery stenosis, and CAS is considered an alternative treatment for carotid artery stenosis.
In this study, the 30-day postoperative MI, stroke, and death rate was 2.53%, and the 30-day postoperative death and stroke rate was 2.47%, which was better than that observed in other studies. Through earlier voluntary registries, the Global Carotid Artery Stent Registry16 included 12 392 CAS procedures in 11 243 patients performed at 53 sites between 1997 and 2002. The technical success rate was 98.9%, and the stroke or death rate was 4.7%. However, the Prospective Registry of Carotid Angioplasty and Stenting (Pro-CAS)17 included 3853 CAS procedures, with a technical success rate of 98% and a stroke and death rate of 2.8%. Recently, in a multicenter randomized trial, CREST, the periprocedural aggregate rate of stroke, MI, and death after CAS was 5.2%.9
EPDs were originally used as a protection factor for preventing infarction in procedures. However, at present the use of an EPD during CAS is optional and not without risk. The complexity of the procedure is increased when an EPD is used, and several unprotected steps are still present during device introduction and retrieval so that a number of microemboli reach the distal end.18 Although most studies reported that CAS was safer with the use of an EPD, Wholey et al16 reported 30-day stroke and death rates of 2.23% and 5.29% with an EPD and without an EPD, respectively (P <0.0001). In a multicenter review by Kastrup et al,19 2357 CAS procedures with the use of protection were compared with 839 procedures without protection. The combined stroke and death rate for cases with an EPD was 1.8%, and without protection this rate was 5.5%, which represented a significant difference (P <0.001). Retrospective analysis of the lead-in phase of the CREST showed a 4.9% 30-day risk of stroke without an EPD (n=81) versus 3.6% with an EPD (n=332, P=0.58).20 In this study, we observed a combined MI, stroke, and death rate of 2.32% for cases with an EPD and 5.71% for cases without protection, and this difference was not significant (P=0.068). Although no significant difference was observed in some studies, the stroke and death rate for cases with an EPD was lower than that without an EPD. Thus, there continues to be controversy regarding the benefit of these expensive devices.21
A number of studies have reported that the incidence of perioperative complications in symptomatic patients is higher than in patients without symptoms. In CAPTURE,22 compared with the asymptomatic cohort, symptomatic statistically patients had a significantly higher risk of 30-day MI, stroke, and death (12.0% for symptomatic vs. 5.4% for asymptomatic, P <0.05). The presence of symptoms was independently associated with adverse outcomes (OR=2.5; 95% CI=1.80-3.47; P <0.0001). In addition, the Pro-CAS trial reached the same conclusion with a perioperative stroke and death rate of 4.3% for symptomatic patients and 2.7% for asymptomatic patients (P <0.05). Experiencing symptoms was also independently associated with adverse outcomes (OR=1.54; 95% CI=1.1-2.1; P=0.008).17 Similarly, in this study, the rates of adverse outcomes in symptomatic patients were higher than those in asymptomatic patients. The 30-day MI, stroke, and death rate was 3.58% in symptomatic patients, but only 1.38% in asymptomatic patients (P=0.003), and having symptoms was independently associated with the 30-day MI, stroke, and death (OR=2.265; 95% CI=1.141-4.493; P=0.019).
In this study, we found that a history of TIA was independently associated with the 30-day MI, stroke, and death rate (OR=1.964; 95% CI=1.046-3.689; P=0.036). Aronow et al23 reported a similar finding of history of TIA as an independent risk factor (OR=3.11; 95% CI=1.19-8.09; P=0.020). Santaannop et al24 also supported this conclusion with univariate and multivariate analyses showing that a history of TIA increased the composite of MI, stroke, or death within 30 days after the intervention (P=0.03).
The number of studies investigating the effects of a preoperative severe neurological deficit on CAS outcome is still lacking. Among studies of CEA, several studies excluded the portion of patients considering benefit. In this study, the analysis showed that for patients with a mRS ≥3 during the procedural period, the MI, stroke, and death rates were significantly higher than those of patients with mRS <3 (7.34% vs. 2.02%, respectively, P=0.001), and multivariate analysis showed that mRS ≥3 is an independent risk factor for perioperative complications (OR=2.899; 95% CI=1.247-6.738; P=0.013). The patients with severe preoperative neurological deficits appeared to have large area cerebral infarction with disturbed cerebrovascular autoregulation and cerebral tissue damage, which lead to reperfusion easier.25 Therefore, detailed preoperative evaluation of neurological function is helpful to detect high-risk patients and plan treatments to prevent the complications.
Cerebrovascular disease patients taking statins have a reduced risk of stroke.26,27 The CAPTURE study22 found no association between statin use and perioperative stroke (OR=0.82; 95% CI=0.58-1.16; P=0.2711), whereas the study of Groschel et al28 found that the 30-day postoperative MI, stroke, and death rate of patients taking statins was significantly lower than that of patients who did not take statins (4% vs. 15%, respectively; P <0.05). Verzini et al29 demonstrated that statins significantly reduce the occurrence of perioperative stroke and death (OR=0.327; 95% CI=0.13-0.80; P=0.016). Similarly, in this study, the postoperative MI, stroke, and death was 1.88% for patients taking statins, whereas it was 3.59% for patients not taking statins (P=0.038). In the multivariate analysis, preoperative statin use was not associated with postoperative MI, stroke, and death (OR=0.560; 95% CI=0.291-1.077; P=0.082).
A learning curve for CEA was demonstrated by Archie.30 In the CAPTURE-2 study,31 a negative correlation between event rates and patient volume was noted graphically. In their later-phase single-arm study, they reported that a threshold of 72 cases was necessary for consistently achieving a death and stroke rate less than 3% in asymptomatic patients. In this study, the 30-day stroke and death rate progressively declined each year with the accumulation of operation experience. We found that the stroke and death rate was less than 3.5% once the interventionalist had performed more than 83 CAS procedures and less than 3.0% once the interventionalist had performed more than 161 CAS procedures. This study included both asymptomatic and symptomatic patients, and this is the reason that the effect of experience is higher than in the CAPTURE-2 study. However, all of the studies demonstrate the fact that a learning curve is present for CAS. The experience of the interventionalist plays a very important role in decreasing the stroke and death rate.
Our study has limitations. First, our data were collected retrospectively rather than gathered prospectively as in the clinical trials. Thus, the data may be less accurate than those gathered prospectively. Second, some other important variables that may influence the results were not considered.
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Keywords:© 2013 Chinese Medical Association
carotid artery stent; carotid stenosis; Chinese population; myocardial infarction; stroke; neurological deficit