Abstract 3308: New Doppler Ultrasound Criteria for Renal Artery In-Stent Restenosis

Abstract

Background: Renal artery Doppler ultrasound (DUS) has been well established as an effective non-invasive screening tool for renal artery stenosis in native renal arteries. Stent placement alters the elastic properties of arteries and would be expected to decrease arterial compliance resulting in higher DUS velocities than non-stented arteries. To date, no criteria have been established for detecting in-stent restenosis (ISR) with DUS. Purpose: To establish the optimal DUS parameters to detect hemodynamically significant renal artery in-stent restenosis. Methods: We included consecutive patients (N=68) with clinically suspected renal artery ISR. Each patient underwent DUS and quantitative renal angiography that were blindly interpreted. Pearson’s correlation coefficients of 0.80 to 0.87 (P<0.0001) suggested strong agreement among observers. Significant ISR was defined as ≤ 70% reduction of in-stent luminal diameter when compared to the nearest normal reference segment. Angiographic criteria were compared to the renal artery peak systolic velocity (PSV) and the renal-aortic ratio (RAR) from corresponding DUS measurements. Receiver Operating Characteristic curves were constructed using PSV and RAR as continuous variables to determine the DUS parameters with the highest sensitivity and specificity for detecting ISR. Results: There was a statistically significant correlation for both PSV and RAR in detecting ISR as defined by quantitative angiography (P<0.0001). PSV>325 cm/sec and RAR>4.9 were most predictive of angiographically significant ISR, while a combination of the two criteria resulted in a greater sensitivity and specificity than either one alone. Conclusion: Renal artery Doppler ultrasound is an effective screening tool for renal artery in-stent restenosis. A PSV of 325 cm/sec and a RAR of 4.9 are most predictive of angiographic in-stent restenosis, with a combination of the two criteria offering the greatest sensitivity and specificity. DUS DETECTION OF ≥70% RENAL ARTERY IN-STENT RESTENOSIS (ISR)