Intima‐Media Thickness Progression Rate and Primary Unassisted Patency Failure in Arteriovenous Fistulas: A Prospective Cohort Study

BACKGROUND: Failure of autogenous arteriovenous fistulas (AV fistulas) due to venous neointimal hyperplasia is a major clinical challenge. Whether the rate of progression in venous intima-media thickness predicts primary unassisted patency failure remains unknown. METHODS: In this prospective cohort study, we performed a 6-month landmark analysis to minimize immortal time bias among patients with newly created AV fistulas. Intima-media thickness was measured serially by ultrasound. We calculated the early progression rate (0-6 months) as the primary predictor and the 0-12 month rate as a sensitivity analysis. Cox proportional hazards models were used to assess the association between the early progression rate and subsequent primary unassisted patency failure. RESULTS: The analysis included 129 patients who were event-free at the 6-month landmark. Over a median follow-up of 13.2 months after the landmark, 35 patients (27.1%) experienced primary unassisted patency failure. Faster early intima-media thickness progression was a strong independent predictor of failure (adjusted hazard ratio [HR] 1.63 per 0.05 mm/year increase; 95% CI 1.41-1.88; p < 0.001), together with baseline intima-media thickness and diabetes. Adding the early progression rate to a model containing clinical and baseline ultrasound variables significantly improved discrimination (C-index increased from 0.69 to 0.76, p = 0.002) and risk reclassification (net reclassification improvement = 0.21, p = 0.008). CONCLUSIONS: Early venous intima-media thickness progression rate is a powerful independent predictor of subsequent AV fistula failure and adds substantial prognostic value beyond standard clinical and ultrasound factors. Serial ultrasound monitoring of this parameter may support the development of risk-adapted surveillance strategies to prolong AV fistula survival.