Q) When should we consider revascularization for patients with asymptomatic carotid stenosis?

A) At this moment in time, we are still waiting for the evidence on whether revascularization in this group of patients is beneficial. CREST-2 trial is ongoing https://www.crest2trial.org/.  This trial compares 3 different methods: best medical treatment (BMT), carotid endarterectomy (CEA) and carotid stent (CAS).

European guideline (2017) recommends carotid revascularization in patients with 60-99% stenosis with life expectancy >5 years and have at least one feature suggesting higher stroke risk on BMT (figure 4 and table 4). In “average surgical risk” patients, CEA should be considered (Class IIa, level B) and in “high risk for CEA” patients, CAS should be considered (Class IIa, level B), provided documented perioperative stroke/death rates are <3%. UpToDate recommends CEA in patients with ≥80% stenosis or patients with progression of stenosis to ≥80% stenosis. 
Recent study showed that in asymptomatic patients, carotid revascularization either CEA or CASE does not portent a higher risk of adverse effect in women than in men.
Cochrane review (2020) comparing CEA versus CAS in this group of patients showed similar short-term and long-term outcomes (risk of stroke or death) however the certainty of the evidence in these people was only moderate.

Reference:
 

1) Aboyans V, Ricco JB, Bartelink MEL, et al. 2017 ESC Guidelines on the Diagnosis and
Treatment of Peripheral Arterial Diseases, in collaboration with the European Society for
Vascular Surgery (ESVS): Document covering atherosclerotic disease of extracranial
carotid and vertebral, mesenteric, renal, upper and lower extremity arteries Endorsed
by: the European Stroke Organization (ESO)The Task Force for the Diagnosis and
Treatment of Peripheral Arterial Diseases of the European Society of Cardiology (ESC)
and of the European Society for Vascular Surgery (ESVS). Eur Heart J. 2018;39(9):763-
816.

2) UptoDate search “Management of asymptomatic carotid atherosclerotic disease”
3) Mayor JM, Salemi JL, Dongarwar D, et al. Sex-Based Differences in Ten-Year Nationwide Outcomes of Carotid Revascularization. J Am Coll Surg. 2019;229(1):38-46.e4.
4) Müller MD, Lyrer P, Brown MM, Bonati LH. Carotid artery stenting versus
endarterectomy for treatment of carotid artery stenosis. Cochrane Database Syst
Rev. 2020;2(2):CD000515. Published 2020 Feb 25.