Study design

The IMPROVE trial is a randomised controlled non-inferiority trial across 5 university and 5 non-university hospitals in the Netherlands, with a 2-year and 5-month inclusion period and 3+ years of follow-up. The IMPROVE trial is funded by ZonMw (DoelmatigheidsOnderzoek Open Ronde 2026). The study is registered at ClinicalTrials.gov (NCT07556887).

Inclusion criteria:

In order to be eligible to participate in this study, a subject must meet all of the following criteria:

● Mentally competent

● 18 years or older

● Recent (<30 days) stroke (modified Rankin scale ≤3) or TIA

● Ipsilateral 30-99% atheromatous stenosis at the carotid bifurcation assessed using non-invasive imaging according to NASCET criteria

● Life expectancy >5 years

● Patient and stenosis are suitable for carotid revascularisation

● Patient is agreeable to randomisation and willing to accept either IMPROVE-based or CAU-based selection method for carotid revascularisation

Exclusion criteria:

A potential subject who meets any of the following criteria will be excluded from participation in this study:

● Cardiac source of embolism

● Carotid stenosis caused by non-atherosclerotic disease e.g. dissection, fibromuscular disease or neck radiotherapy

● MRI contra-indications

● Pregnancy
 

Patients will be randomized to the control (CAU) or intervention (IMPROVE) group. 

Patients within the control group will be selected for carotid revascularization vs OMT-only as in care as usual. 

In the intervention group, high-risk patients (≥10% predicted risk of ipsilateral ischemic stroke within 3 years on OMT by IMPROVE) will be recommended by the IMPROVE decision rule to undergo carotid revascularisation (CEA/CAS) in combination with OMT, while lower risk patients will be recommended to have OMT only.

The composite of any stroke or death within 44 days after randomisation or ipsilateral ischemic stroke at any time during subsequent follow-up.

613 patients