Clinical Outcomes of Carotid Endarterectomy in Patients With Carotid Artery Tandem Lesions
Background and Purpose—When carotid artery tandem lesions are present, the benefits of carotid endarterectomy (CEA) to reduce recurrent stroke remain uncertain. The present retrospective cohort study aimed to determine the clinical outcomes of CEA for carotid artery tandem stenosis that was diagnosed by contrast-enhanced magnetic resonance angiography.
Methods—Six hundred forty-seven consecutive patients underwent CEA between January 2001 and December 2010. Tandem stenosis, defined as a significant carotid bifurcation stenosis and identifiable stenosis of ≥50% of any downstream distal cerebral artery, was identified in 92 patients (14.2%) by contrast-enhanced magnetic resonance angiography. Patients with and without tandem stenosis were compared in terms of CEA outcomes. The primary end point was the composite of any stroke, myocardial infarction, or death during the periprocedural period or ipsilateral stroke within 4 years after CEA.
Results—Tandem stenosis did not associate with ipsilateral stroke during postoperative follow-up. The 2 groups did not differ in terms of estimated 4-year primary end point rates (8.7% versus 3.8%; P=0.07) or ipsilateral stroke-free (P=0.56), any stroke-free (P=0.89), or overall survival (P=0.41) rates.
Conclusions—After diagnosis by contrast-enhanced magnetic resonance angiography, patients with and without tandem stenosis had similar rates of stroke and death.
Randomized clinical trials have established the efficacy of carotid endarterectomy (CEA) for patients with significant internal carotid artery stenosis.1–3 However, the benefits of this operation to reduce recurrent stroke, when both intracranial and extracranial carotid artery disease are present, remain uncertain because previous studies on this question had varying results.4–8 Notably, the degree of tandem stenosis in all of these previous studies was assessed by intra-arterial digital subtraction angiography. However, in recent times, there has been a pronounced trend toward the use of noninvasive diagnostic modalities, such as the combination of screening Duplex ultrasonography and contrast-enhanced magnetic resonance angiography (CEMRA).6
This study aimed to retrospectively evaluate the short-term operative risk and long-term outcome of patients with and without carotid artery tandem stenosis who underwent CEA in the present era, where noninvasive diagnostic techniques (specifically CEMRA) are used to evaluate carotid artery disease.
This retrospective observational study was based on data from medical records. The study protocol was approved by the hospital’s Institutional Review Board. Between January 2001 and December 2010, 647 consecutive patients with a significant carotid bifurcation stenosis (ie, ≥70% in asymptomatic patients and ≥50% in symptomatic patients), as defined by criteria established by the North American Symptomatic Carotid Endarterectomy Trial (NASCET),1 who underwent a CEA in tertiary/university hospital were included in this study.
Significant intracranial disease was defined as identifiable stenosis (≥50% diameter reduction) of the carotid siphon or other major intracranial vessel, as noted by the radiologist in the official CEMRA report. Risk factors of interest and other data, including clinical presentation, imaging studies, surgical details, short-term operative risk, and long-term outcome, were recorded prospectively for all consecutive patients in an Excel database (Microsoft Corp., Redmond, Washington, USA) and analyzed retrospectively. The primary end point was the composite of any stroke, myocardial infarction, or death during the periprocedural period or ipsilateral stroke within 4 years after CEA.
Student’s t test, χ2 test, and Kaplan−Meier survival curves with log-rank test were used where appropriate. Multivariate analysis was performed by using the Cox proportional hazards model. P<0.05 was considered to indicate significant differences.
Of the 647 patients undergoing CEA, ipsilateral tandem stenosis was identified in 92 (14.2%) patients by CEMRA. Of the 92 patients with tandem stenosis, the stenotic lesions of the intracranial vessel involved the middle cerebral artery in 49 patients (53.3%), anterior cerebral artery in 15 (16.3%), carotid siphon in 2 (2.2%), both carotid siphon and middle cerebral artery in 13 (14.1%), both anterior cerebral artery and middle cerebral artery in 10 (10.9%), and both carotid siphon and anterior cerebral artery in 3 (3.3%). The groups with and without tandem stenosis did not differ significantly with regard to demographics, risk factors, or clinical characteristics, except that the tandem stenosis patients were more likely to have hypertension, preoperative antiplatelet therapy, and longer postoperative follow-up. Also, the patients with tandem stenosis were less likely to have carotid stenosis on the left side (Table I in the online-only Data Supplement).
Diabetes mellitus was the only risk factor that associated significantly with ipsilateral stroke in univariate (P=0.01) and multivariate (P=0.01) analyses (Table 1). Tandem stenosis did not associate with ipsilateral stroke (P=0.12) during follow-up. The groups with and without tandem stenosis did not differ significantly in terms of primary end point incidence during the periprocedural period (4.3% versus 2.2%; P=0.22) or estimated 4-year rates of the primary end point (8.7% versus 3.8%; P=0.07), although they did differ significantly in the incidence of any minor ipsilateral stroke (5.4% versus 1.6%; P=0.045; Table 2). Kaplan−Meier survival analysis showed that the groups with and without tandem stenosis had similar ipsilateral stroke-free (P=0.56), any stroke-free (P=0.89), and overall survival (P=0.41) rates (Figure).
In this study, carotid artery tandem stenosis was observed in 14.2% of patients undergoing CEA. Tandem stenosis did not associate with ipsilateral stroke during follow-up. This is consistent with similar studies using intra-arterial digital subtraction angiography for diagnosis that have reported a similar rate of stroke and death between the groups with and without tandem stenosis.4,5 However, since tandem stenosis was measured in our study by CEMRA, this may be both a unique feature and a limitation of this study.
Intra-arterial digital subtraction angiography remains the gold standard for carotid imaging but is relatively expensive and carries a small but significant risk of causing a stroke or death, which could reduce the overall benefits of CEA.6 These concerns have generated substantial interest in the use of alternative noninvasive imaging modalities. CEMRA has emerged as a significant technical improvement and there has been a recent, growing trend toward the use of noninvasive modalities, with the combination of screening Duplex ultrasonography and CEMRA emerging as the preferred strategy.6
Although patients with tandem stenosis are at increased risk of stroke, they seem to have a lower risk than untreated patients with a significant carotid bifurcation stenosis. Several limitations should be noted. This study has a retrospective design, and there was no adjustment for baseline differences between the 2 groups. Furthermore, this study used CEMRA with the lower diagnostic accuracy compared with intra-arterial digital subtraction angiography. Despite the potential limitations, this study showed that patients with and without tandem stenosis have similar rates of stroke and death. Thus, it provides new information that will aid the optimal management of carotid artery tandem stenosis that is diagnosed by CEMRA.
The online-only Data Supplement is available with this article at http://stroke.ahajournals.org/lookup/suppl/doi:10.1161/STROKEAHA.114.007181/-/DC1.
- Received August 21, 2014.
- Revision received August 27, 2014.
- Accepted August 28, 2014.
- © 2014 American Heart Association, Inc.
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