Effects of Intensive Medical Therapy on Microemboli and Cardiovascular Risk in Asymptomatic Carotid Stenosis

Objective: To assess the effect of more intensive medical therapy on the rate of transcranial Doppler (TCD) microemboli and cardiovascular events in patients with asymptomatic carotid stenosis (ACS). Design: A prospective study. Setting: A teaching hospital. Patients: Four hundred sixty-eight patients with ACS greater than 60% by Doppler peak velocity. Main Outcome Measures: We compared (1) the proportion of ACS patients who had microemboli on TCD, (2) cardiovascular events, (3) rate of carotid plaque progression, and (4) baseline medical therapy, before and since 2003. Results: Among 468 ACS patients, 199 were enrolled between January 1, 2000, and December 31, 2002; and 269 were enrolled between January 1, 2003, and July 30, 2007. Microemboli were present in 12.6% before 2003 and 3.7% since 2003 (P<.001). The decline in microemboli coincided with better control of plasma lipids and slower progression of carotid total plaque area. Since 2003, there have been significantly fewer cardiovascular events among patients with ACS: 17.6% had stroke, death, myocardial infarction, or carotid endarterectomy for symptoms before 2003, vs 5.6% since 2003 (P<.001). The rate of carotid plaque progression in the first year of follow-up has declined from 69 mm(2) (SD, 96 mm(2)) to 23 mm(2) (SD, 86 mm2) (P<.001). Conclusions: Cardiovascular events and microemboli on TCD have markedly declined with more intensive medical therapy. Less than 5% of patients with ACS now stand to benefit from revascularization; patients with ACS should receive intensive medical therapy and should only be considered for revascularization if they have microemboli on TCD.