Instantaneous Wave-Free Ratio Measurement During Intracranial Submaximal Angioplasty: Case Series and 2-Dimensional Operative Video.

BACKGROUND: Instantaneous wave-free ratios (iFRs) are functional measures of arterial stenosis that have become essential to interventional cardiology procedures. Their use for intracranial submaximal angioplasty (angioplasty with an undersized balloon) has not been studied extensively. OBJECTIVE: To describe the feasibility and technique of iFR measurement for stenosis assessment during intracranial angioplasty. METHODS: We present a series of consecutive patients treated between January 1, 2017 and June 30, 2018 with submaximal intracranial angioplasty in whom pre- and postprocedure iFR measurements were obtained with a Verrata-Volcano pressure wire (Philips, Amsterdam, The Netherlands). We collected patient data on age, sex, comorbid conditions, presenting complaints, modified Rankin scale (mRS) score at admission, neurological findings, procedure duration, fluoroscopy time, intraprocedural complications, length of hospital stay, and mRS score at last clinical follow-up (favorable outcome, 0-2). Angiographic stenosis severity and iFR values were recorded before and after angioplasty. RESULTS: A total of 12 patients underwent iFR-guided angioplasty during the study period. The median patient age was 69.5 yr (range 48-81 yr). All patients had symptomatic intracranial arterial stenosis (3-basilar, 2-vertebral, 6-middle cerebral, 1-internal carotid). Preangioplasty stenosis ranged from 55% to 90%. The median postangioplasty reduction in stenosis was 17% (range 9%-30%). Preangioplasty values ranged from 0.30 to 0.40 (n = 4). Postangioplasty values ranged from 0.6 to 0.9 (n = 5). iFR values improved considerably in all patients. No procedure-related complications occurred. The median follow-up was 8.9 mo (range 3-25 mo). Follow-up outcomes were favorable in 10 patients. CONCLUSION: iFR measurement before and after intracranial angioplasty is feasible. It may be used to assess the adequacy of intracranial angioplasty.