According to the ACAS trial, carotid endarterectomy benefits asymptomatic patients when the degree of internal carotid stenosis exceeds what threshold, provided perioperative stroke and death rates stay below 3 percent?
- A 40 percent
- B 50 percent
- C 60 percent ✓
- D 80 percent
Correct answer: C. 60 percent
Explanation
ACAS showed that in asymptomatic stenosis of 60 percent or more, endarterectomy combined with medical therapy roughly halved the five year ipsilateral stroke risk compared with medical therapy alone, but only when surgical morbidity and mortality remained under 3 percent. The 70 percent figure applies to symptomatic patients in trials such as ECST, and 50 percent was the lower bound studied in symptomatic cohorts, not the asymptomatic threshold.
Reference: Bailey and Love's Short Practice of Surgery, 28th ed.
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Written and medically reviewed by the StethoPrep medical team.