Medical therapy may prevent strokes in asymptomatic carotid stenosis
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Absolute risk reduction for fatal and nonfatal strokes in patients who underwent early carotid endarterectomy was less than half the risk difference from trials initiated 20 years ago, researchers found.
The study published in JAMA Neurology also determined that this absolute reduction was no longer statistically significant when accounting for the competing risk for nonstroke deaths.
“Given the upfront perioperative risks associated with carotid endarterectomy, initial medical therapy may be an equally acceptable treatment strategy for the management of patients with asymptomatic carotid stenosis,” Salomeh Keyhani, MD, MPH, professor of medicine at University of California, San Francisco, School of Medicine, and colleagues wrote.
In this comparative effectiveness study, researchers assessed data from 5,221 veterans aged at least 65 years who underwent carotid imaging from 2005 to 2009. Patients were excluded if they had carotid stenosis less than 50%, hemodynamically insignificant stenosis and a history of transient ischemic attack or stroke 6 months before imaging was performed.
Two cohorts were formed: patients assigned initial medical therapy (n = 2,509; mean age, 74 years; 99% men) and those assigned carotid endarterectomy (n = 2,712; mean age, 74 years; 99% men). Both treatment options were given within 1 year after index carotid imaging. Follow-up was conducted for 5 years. Analyses used in the Asymptomatic Carotid Surgery Trial were emulated in this trial to estimate the comparative effectiveness of carotid endarterectomy and initial medical therapy to prevent nonfatal and fatal strokes.
The rate of stroke or death within 30 days of carotid endarterectomy was 2.5% (95% CI, 2-3.1). At 5 years, the risk for fatal and nonfatal stroke was lower in the carotid endarterectomy group vs. the initial medical therapy group (5.6% vs. 7.8%; risk difference, 2.3%; 95% CI, 4 to 0.3).
When the competing risk for death was incorporated, the risk difference between patients assigned carotid endarterectomy and those assigned initial medical therapy was lower and not statistically significant (risk difference, 0.8%; 95% CI, 2.1 to 0.5).
In patients who met randomized controlled trial inclusion criteria, the risk for fatal and nonfatal strokes at 5 years was 5.5% (95% CI, 4.5-6.5) for the carotid endarterectomy group and 7.6% (95% CI, 5.7-9.5) for the initial medical therapy group (risk difference, 2.1%; 95% CI, 4.4 to 0.2). A risk difference of 0.9% resulted when accounting for competing risks (95% CI, 2.9 to 0.7).
“The decreased stroke risk in patients with carotid artery stenosis, the persistent upfront perioperative risks and the small difference in stroke risk between the two treatment strategies suggest that patients treated with carotid endarterectomy would now require a longer time to accrue enough stroke reduction benefit to justify the upfront risks of the surgical procedure,” Keyhani and colleagues wrote.
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