Evaluation of arteriovenous fistula maturation and early prediction of clinical eligibility, using ultrasound: The Fistula Maturation Evaluation (FAME) Study

Introduction: The study of time-related alterations of ultrasound-determined parameters during maturation, and the assessment of time to hemodynamic maturation, enabling early prediction of clinical eligibility, of hemodialysis autologous arteriovenous fistulae (AVF). Methods: This is an observational, prospective, study of only AVF-eligible patients referred for access creation, from 02/2019 to 02/2022 (ClinicalTrials.gov identifier: NCT0473687). Brachial artery diameter (dBA), access flow volume (FV), non-augmented efferent vein diameter (dEV), resistivity index (RI), and efferent vein total wall thickness (tEV), were assessed by ultrasound. Measurements were conducted daily in the first week and repeated on days 14, 21, 30, 60, and 90, postoperatively. The primary endpoint included the documentation of serial changes of flow and structural parameters related to AVF maturation in the first 90 days of the post-operative period and maturation early prediction. Secondary endpoints included the determination of factors affecting maturation. Results: One hundred one participants (mean age, 67 +/- 6 years; 76 males) were enrolled. Average dBA and FV reached maximum on day 60 (5.64 +/- 0.85 mm) and 90 (1.172 +/- 617 mL/min), respectively. Day 7 values of dBA (5.48 +/- 0.73 mm) and FV (1.039 +/- 531 mL/min) did not alter significantly during the follow-up period. Parameters indicative of clinical functionality, dEV (5.82 +/- 0.90 mm) and tEV (0.493 +/- 0.10 mm), reached approximately 90% of maximum (6.66 +/- 1.42 mm and 0.526 +/- 0.11 mm), by day 14. RI reached minimum on day 30 (0.46 +/- 0.09), without significant changes after day 2 (0.48 +/- 0.09, p = 0.284). A significant correlation was identified, between day 7 FV and day 60 dEV (r = 0.40, p = 0.0002). A FV cut-off value >= 657.51 mL/min, on day 7, predicted successful fistula maturation with 85% sensitivity and 100% specificity. Multivariate analysis identified female gender, age >75, diabetes, and wrist access as independent predictors of decreased values of maturation parameters. Conclusion: Hemodynamic maturation is completed by the first postoperative week, while AVF is clinically functional, by the second. FV can be used for early prediction of maturation.