1. Absolute risk reduction of stroke in asymptomatic carotid stenosis was significantly lower than it was two decades ago.
2. Advances in stroke prevention suggest that medical therapy may be an acceptable treatment strategy for this population.
Evidence Rating Level: 2 (Good)
Carotid endarterectomy (CEA) has been shown effective in both asymptomatic and symptomatic patients with carotid stenosis. However, the clinical trials upon which we have relied for this information may not reflect the advances made in primary stroke prevention. For this reason, revascularization may not be the preferred method of intervention among patients with carotid stenosis. This comparative effectiveness study used databases of the U.S. Veterans Affairs to investigate the differences between initial medical therapy and CEA in preventing strokes among patients with asymptomatic carotid stenosis. Patients without a carotid imaging report, those with a history of stroke within six months of index imaging, and those with carotid stenosis of less than 50% or hemodynamically insignificant stenosis were excluded from subsequent analyses. Of the 5,221 patients included, 51.9% received CEA (M [SD] age = 73.6 [6.0] years, 1.2% female) and 48.1% received initial medical therapy (M [SD] age = 73.6 [ 6.0] years, 1.2% female) within one year of the index carotid imaging. Perioperative complications in the form of stroke or death within 30 days among the CEA group was 2.5% (95% CI 2.0 to 3.1). Although the five-year risk of strokes, both fatal and nonfatal, was lower among individuals randomized to CEA compared to initial medical therapy (difference 2.2%, risk difference -2.3%, 95% CI -4.0 to -0.3), differences in risk were not significant when incorporating competing risk of death (risk difference -0.8%, 95% CI -2.1 to 0.5). Among those who met full RCT inclusion criteria, the five-year risk of strokes was 5.5% among the CEA group (95% CI 4.5 to 6.5) and 7.6% among the initial medical therapy group (95% CI 5.7 to 9.5) with a risk difference of -2.1 (95% CI -4.4 to -0.2). Competing risk analysis resulted in a non-significant finding (risk difference -0.9%, 95% CI -2.9 to 0.7). This study highlights that the absolute reduction in stroke risk associated with early CEA was significantly lower than the risk difference from two decades ago, with a lack of significance when competing risks were accounted for. Therefore, improvements in stroke prevention may suggest that medical therapy is an acceptable treatment in patients with asymptomatic carotid stenosis.
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