Fractional Flow Assessment for the Evaluation of Intracranial Atherosclerosis: A Feasibility Study
ZhongRong Miao1, David S Liebeskind2, WaiTing Lo3
1Departments of Interventional Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China; China National Clinical Research Center for Neurological Diseases, Beijing, China.
Insights
Fractional flow measurement using a pressure guidewire is a safe and feasible method for assessing intracranial stenosis. This technique shows promise for evaluating ischemic stroke risk, complementing traditional stenosis measurements.
Area of Science:
- Neurology
- Interventional Neuroradiology
- Cardiovascular Physiology
Background:
- Current selection for endovascular intervention in intracranial atherosclerosis relies on luminal stenosis.
- Coronary studies indicate fractional flow measurements are superior to anatomical stenosis for assessing ischemia and guiding intervention.
Purpose of the Study:
- To assess the technical feasibility and safety of using a pressure guidewire for fractional flow measurement in intracranial stenoses.
- To explore the potential of fractional flow measurements for assessing ischemic stroke risk.
Main Methods:
- A feasibility study involving 20 patients with severe intracranial stenosis.
- Measurement of luminal stenosis, distal to proximal pressure ratios (fractional flow), and fractional flow gradients.
- Documentation of procedural success rates and safety outcomes.
Main Results:
- Successful pressure guidewire crossing of stenosis in all 20 patients.
- Fractional flow and pressure gradients showed only a modest correlation with luminal stenosis.
- Mean pre-intervention fractional flow was 0.66, improving to 0.88 post-intervention.
Conclusions:
- Fractional flow measurement via pressure guidewire is technically feasible and safe for intracranial stenosis.
- Further research is required to validate its utility in ischemic stroke risk assessment.
Purpose:
Current studies on endovascular intervention for intracranial atherosclerosis select patients based on luminal stenosis. Coronary studies demonstrated that fractional flow measurements assess ischemia better than anatomical stenosis and can guide patient selection for intervention. We similarly postulated that fractional flow can be used to assess ischemic stroke risk.
Methods:
This was a feasibility study to assess the technical use and safety of applying a pressure guidewire to measure fractional flow across intracranial stenoses. Twenty patients with severe intracranial stenosis were recruited. The percentage of luminal stenosis, distal to proximal pressure ratios (fractional flow) and the fractional flow gradients across the stenosis were measured. Procedural success rate and safety outcomes were documented.
Results:
All 20 patients had successful crossing of stenosis by the pressure guidewire. Ten patients underwent angioplasty, and 5 had stenting performed. There was one perforator stroke, but not related to the use of the pressure wire. For the 13 patients with complete pre- and postintervention data, the mean preintervention stenosis, fractional flow and translesional pressure gradient were 76.2%, 0.66 and 29.9 mm Hg, whilst the corresponding postintervention measurements were 24.7%, 0.88 and 10.9 mm Hg, respectively. Fractional flow (r = -0.530, p = 0.001) and the translesional pressure gradient (r = 0.501, p = 0.002) only had a modest correlation with the luminal stenosis.
Conclusion:
Fractional flow measurement by floating a pressure guidewire across the intracranial stenosis was technically feasible and safe in this study. Further studies are needed to validate its use for ischemic stroke risk assessment.
