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Infarct Recurrence in Intracranial Atherosclerosis: Results from the MyRIAD Study
Jose G Romano1, Shyam Prabhakaran2, Azhar Nizam3
1University of Miami, 1120 NW 14th Street, Suite 1357, Miami, FL 33136, USA.
Insights
Intracranial atherosclerotic disease (ICAD) patients face high risks of recurrent stroke and new infarcts. Current imaging biomarkers did not predict these events in this study.
Area of Science:
- Neurology
- Radiology
- Vascular Medicine
Background:
- Intracranial atherosclerotic disease (ICAD) is a significant cause of ischemic stroke, associated with a high risk of recurrence.
- Understanding the mechanisms of recurrent cerebral ischemia in ICAD is crucial for effective treatment strategies.
Purpose of the Study:
- To investigate the utility of imaging biomarkers in predicting recurrent ischemic events in patients with ICAD.
- To assess impaired antegrade flow, poor distal perfusion, abnormal vasoreactivity, and artery-to-artery embolism as potential mechanisms.
Main Methods:
- A prospective, multicenter observational study enrolled 105 patients with recent ischemic stroke or TIA due to ICAD (50-99% stenosis) on medical management.
- Quantitative MRA (QMRA), perfusion MRI (PWI), transcranial Doppler vasoreactivity (VMR), and emboli detection studies (EDS) were performed.
- Primary outcome was ischemic stroke within 1 year; secondary outcomes included TIA and new infarcts on MRI at 6-8 weeks.
Main Results:
- Among 102 participants, 8.8% experienced a primary outcome (stroke) and 5.9% a TIA within 1 year.
- New infarcts were observed in 24.7% of patients at 6-8 weeks.
- Biomarkers showed prevalence of low flow (25.5%), poor perfusion (43.5%), impaired vasoreactivity (67.5%), and microemboli (39.0%), but none predicted outcomes.
Conclusions:
- Patients with ICAD have a high risk of cerebrovascular events and subacute infarcts despite medical therapy.
- Current hemodynamic and plaque instability imaging biomarkers did not effectively identify patients at higher risk for recurrence.
- Further research is required to identify predictive mechanisms and long-term consequences of recurrent ischemia in ICAD.
Background:
Intracranial atherosclerotic disease (ICAD) is a common cause of ischemic stroke with a high risk of clinical stroke recurrence. Multiple mechanisms may underlie cerebral ischemia in this condition. The study's objective is to discern the mechanisms of recurrent ischemia in ICAD through imaging biomarkers of impaired antegrade flow, poor distal perfusion, abnormal vasoreactivity, and artery-to-artery embolism.
Methods:
This prospective multicenter observational study enrolled patients with recent (≤21 days) ischemic stroke or transient ischemic attack (TIA) caused by ICAD with 50-99% stenosis treated medically. We obtained baseline quantitative MRA (QMRA), perfusion MRI (PWI), transcranial Doppler vasoreactivity (VMR), and emboli detection studies (EDS). The primary outcome was ischemic stroke in the territory of the stenotic artery within 1 year of follow-up; secondary outcomes were TIA at 1 year and new infarcts in the territory on MRI at 6-8 weeks.
Results:
Amongst 102 of 105 participants with clinical follow-up (mean 253±131 days), the primary outcome occurred in 8.8% (12.7/100 patient-years), while 5.9% (8.5/100 patient-years) had a TIA. A new infarct in the territory of the symptomatic artery was noted in 24.7% at 6-8 weeks. A low flow state on QMRA was noted in 25.5%, poor distal perfusion on PWI in 43.5%, impaired vasoreactivity on VMR in 67.5%, and microemboli on EDS in 39.0%. No significant association was identified between these imaging biomarkers and primary or secondary outcomes.
Conclusions:
Despite intensive medical management in ICAD, there is a high risk of clinical cerebrovascular events at 1 year and an even higher risk of new imaging-evident infarcts in the subacute period after index stroke. Hemodynamic and plaque instability biomarkers did not identify a higher risk group. Further work is needed to identify mechanisms of ischemic stroke and infarct recurrence and their consequence on long-term physical and cognitive outcomes.
Trial Registration:
ClinicalTrials.gov: NCT02121028.
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