Imaging practices following peripheral vascular intervention in chronic limb-threatening ischemia and association with amputation outcomes

Abstract

Background: Peripheral vascular interventions (PVI) in chronic limb-threatening ischemia (CLTI) are used to prevent amputation. However, imaging practices following PVI and their correlation with amputation outcomes remain unclear. Methods: Using Medicare-linked Vascular Quality Initiative data (2017–2019), we identified imaging tests (ankle–brachial index [ABI], duplex ultrasound, magnetic resonance angiography, computed tomography angiography) ordered within 1 year post-PVI for CLTI. Site variability was assessed using median odds ratio (MOR) and intraclass correlation coefficient (ICC). The association between post-PVI imaging and 1-year major amputation was examined using competing risk analyses in a propensity-matched cohort. Results: We included 10,006 patients (mean age: 72.1 ± 11.0 years); 25.5% received no imaging. Over 50% of imaging tests were ABI and 83.1% were ordered within 3 months. Significant site variability was noted (none vs ⩾ 1: MOR 1.64, 95% CI 1.50–1.78; ICC 7.6%, 95% CI 5.2–9.9%; per one-unit increase in monthly volume: MOR 1.06, 95% CI 1.05–1.07; ICC 9.4%, 95% CI 7.0–11.8%). Having none versus ⩾ 1 imaging tests post-PVI occurred more in patients with lower 1-year major amputation rates (5.7%, 95% CI 5.0–6.6% vs 8.8%, 95% CI 7.9–9.9%, p < 0.001; subdistribution hazard ratio [SHR] 0.63, 95% CI 0.53–0.76, p < 0.001). More imaging ordered was correlated with a higher rate of major amputation (SHR 1.83, 95% CI 1.52–2.20, p < 0.001). Conclusions: Imaging practices post-PVI for CLTI are highly variable. Imaging tests are more often ordered in patients with higher amputation rates, but causality cannot be inferred. Additional information about symptom status and access to care are necessary. Standardized follow-up imaging protocols need to be developed and studied for improved clinical outcomes.