Background~Carotid endarterectomy (CEA) and carotid stenting (CAS) are often performed for subgroups of patients for whom procedural benefit has not been established in randomised trials and despite evidence of serious procedural risk. Patients also receive best medical treatment which is previously proven to reduce the risk of early recurrent neurological symptoms especially within the first 14 days of symptom onset (6). Further, there is no current evidence of procedural benefit compared to modern optimal medical intervention alone (lifestyle coaching and medication) for any individuals with carotid arterial disease (4,5). In some places the COVID-19 pandemic has made it difficult or impossible to perform CEA and CAS. Current guidelines recommend rapid revascularisation of symptomatic carotid stenosis. These guidelines are largely based on data from clinical trials performed at a time when best medical therapy was potentially less effective than today (4,5).~At a minimum these invasive interventions must be better justified.~Aim/Objectives~To measure the rate of ipsilateral stroke, and other arterial disease complications in individuals with advanced (50-69% and 70-99%) symptomatic carotid stenosis who, for any reason, are managed using current best medical intervention alone. Reasons for a nonprocedural approach may include insufficient resources caused by the coronavirus pandemic, unproven procedural benefit, anticipated procedural futility and/or net harm, or patient refusal. Hence, the investigators will study patients for whom carotid procedures are not possible or considered unethical.~To compare the CASCOM Pilot Study rate of ipsilateral stroke for symptomatic patients with that reported in the North American Symptomatic Carotid Endarterectomy Trial (NASCET) and the European Carotid Surgery Trial (ECST).~Methods CASCOM Pilot Study is a prospective observational cohort study of current best medical intervention alone for stroke prevention. It consists of a prospective cohort study of current best medical intervention alone for stroke prevention. The investigators will separate patients into those who would and would not have been eligible for past randomised CEA trials. The investigators plan to study 310 symptomatic patients with 50-69% and 120 symptomatic patients with 70-99% ipsilateral stenosis using 'REDCap' (Research Electronic Data Capture) for case reporting.~Expected Findings and Significance In CASCOM Pilot Study the investigators expect at least 50% lowering of the ipsilateral stroke rate compared to that seen with medical intervention alone in past randomised controlled trials with very similar inclusion criteria.~If correct, CASCOM Pilot Study will provide new evidence that past randomised trials of CEA and CAS are outdated. Furthermore, this study will improve standards for stroke prevention and other arterial disease complications as well as to contribute to a necessary major international, multi-specialty observation study.~Primary Hypotheses:~Symptomatic Patients~The 2-year rate of ipsilateral stroke from time of recruitment in symptomatic patients with ipsilateral 70-99% (NASCET) carotid stenosis receiving current best medical intervention alone will be at least 50% lower compared to patients given medical intervention alone in NASCET(their rate was 26.0% using life-table analysis.~The 2-year rate of ipsilateral stroke from time of recruitment in symptomatic patients with ipsilateral 50-69% (NASCET) carotid stenosis receiving current best medical intervention alone will be at least 50% lower compared to patients given medical intervention alone in NASCET (their rate was 14.0% using life-table analysis.~Secondary Hypotheses:~Symptomatic Patients For symptomatic patients with 50-99% (NASCET) stenosis receiving current best medical intervention alone the 3-5-year ipsilateral carotid ischaemic stroke rate after randomization will be at least 50% lower compared to patients who had medical intervention alone in ECST and NASCET. 5-year ipsilateral ischaemic stroke rates for randomised trial patients were measured using pooled ECST and NASCET results, life-table analyses and according to different time intervals between the last ischaemic event and randomization.~Hypothesis 1:~Symptomatic Patients The 2-year rate of ipsilateral stroke in symptomatic patients with 70-99% (NASCET) carotid stenosis receiving current best available medical intervention alone will be at least 50% lower compared to patients given medical intervention alone in NASCET. Require: 104/0.85 = 121 patients.~Hypothesis 2:~The 2-year rate of ipsilateral stroke in symptomatic patients with 50-69% (NASCET) carotid stenosis receiving current best available medical intervention alone will be at least 50% lower compared to patients given medical intervention alone in NASCET. Require: 200/0.85 = 230 patients.~CASCOM Pilot study will also validate the CAR-Score < 15% for a 3-year risk for ipsilateral stroke in patients treated with best medical intervention.~We hope this pilot study would be a guide for implementation of an international multicenter CASCOM study.
Carotid endarterectomy (CEA) and carotid stenting (CAS) are often performed for subgroups of patients for whom procedural benefit has not been established in randomised trials and despite evidence of serious procedural risk. In some places, the COVID-19 pandemic has made it difficult or impossible to perform CEA and CAS in time. This study aims to measure the rate of ipsilateral stroke and other complications in individuals with symptomatic carotid stenosis, whom for any reason are managed using current best medical intervention alone. The investigators expect at least 50% lowering of the ipsilateral stroke rate compared to that seen with medical intervention alone in past randomised trials.