A large single-center study has found that carotid artery restenosis (post-stenting) greater than 50 percent and cerebral events rather than retinal events are risk factors for recurrent stroke. Clopidogrel, however, reduced the risk, according to the investigation published in the February issue of Circulation: Cardiovascular Interventions..
The authors noted that previous outcomes data for this patient population mixed symptomatic with asymptomatic patients. Therefore, they sought to determine the risk factors for recurrent stroke associated with carotid stenting only in symptomatic patients.
Marc S. Randall, MD, of the Sheffield Teaching Hospitals NHS Foundation Trust in the U.K., and colleagues evaluated data from 563 carotid stenting procedures performed on symptomatic patients between March 1996 and August 2008.
In the hospital, treatment decisions are made by multidisciplinary teams, but procedures are performed by interventional vascular radiologists. Cerebral protection devices are used whenever possible, and dual-antiplatelet therapy of clopidogrel and aspirin is used during the procedure and for 28 days afterward. A small number of patients in the study before 2002 did not receive the full follow-up of dual-antiplatelet therapy.
After a four-year follow-up, researchers found that ipsilateral stroke occurred in 34 patients: 4.8 percent at 30 days, 7 percent at one year and 9.5 percent at four years. The rates improved to 2.7 percent, 4.1 percent and 4.5 percent, respectively, when patients were treated with optimal therapy, which included clopidogrel, statin and embolic protection.
Results showed that the presence of persistent or recurrent stenosis greater than 50 percent was a significant risk factor for ipsilateral stroke.
Researchers also found that the hazard ratio for cerebral events was six times higher than that for retinal events. “We have confirmed that retinal events have a significantly lower risk of future recurrence than cortical events,” the authors wrote.
The use of clopidogrel during procedures reduced the risk of ipsilateral stroke in patients. After the procedure 413 patients were treated with clopidogrel, compared to 148 who were not. After a four-year follow-up period, 94.1 percent of patients treated with the drug remained stroke free compared to 81.3 percent not treated with the drug.
“Multivariate analysis in this case showed that only clopidogrel had clear independent benefit on the outcomes of ipsilateral stroke and vascular death in the long-term follow-up, despite statin and clopidogrel therapy appearing to be beneficial in univariate analysis,” the authors wrote.
They suggested that the "impact of clopidogrel on long-term outcomes is likely to be due to its dramatic effects at 30 days. This raises questions about the possible benefits of prolonging post-stenting clopidogrel therapy to see whether this benefit can be extended."
Investigators noted that their results "compare favorably with the data from the randomized controlled trials of carotid stenting and surgery, suggesting that the durability of the procedure can be maintained when patients not conforming to
randomized control trial entrance criteria are included in outcome analysis."