Pre-existing and Postoperative Intimal Hyperplasia and Arteriovenous Fistula Outcomes

Background: The contribution of intimal hyperplasia (IH) to arteriovenous fistula (AVF) failure is uncertain. This observational study assessed the relationship between pre-existing, postoperative, and change in IH over time and AVF outcomes. Study Design: Prospective cohort study with longitudinal assessment of IH at the time of AVF creation (pre-existing) and transposition (postoperative). Patients were followed up for up to 3.3 years. Setting & Participants: 96 patients from a single center who underwent AVF surgery initially planned as a 2-stage procedure. Veins and AVF samples were collected from 66 and 86 patients, respectively. Matched-pair tissues were available from 56 of these patients. Predictors: Pre-existing, postoperative, and change in IH over time. Outcomes: Anatomic maturation failure was defined as an AVF that never reached a diameter > 6. mm. Primary unassisted patency was defined as the time elapsed from the second-stage surgery to the first intervention. Measurements: Maximal intimal thickness in veins and AVFs and change in intimal thickness over time. Results: Pre-existing IH (>0.05mm) was present in 98% of patients. In this group, the median intimal thickness increased 4.40-fold (IQR, 2.17- to 4.94-fold) between AVF creation and transposition. However, this change was not associated with pre-existing thickness (r ² =0.002; P =0.7). Ten of 96 (10%) AVFs never achieved maturation, whereas 70% of vascular accesses remained patent at the end of the observational period. Postoperative IH was not associated with anatomic maturation failure using univariate logistic regression. Pre-existing, postoperative, and change in IH over time had no effects on primary unassisted patency. Limitations: The small number of patients from whom longitudinal tissue samples were available and low incidence of anatomic maturation failure, which decreased the statistical power to find associations between end points and IH. Conclusions: Pre-existing, postoperative, and change in IH over time were not associated with 2-stage AVF outcomes.