Duplex Ultrasound for Diagnosis of Failing Stents Placed for Arterial Occlusive Disease
Hong Zheng, DO, Keith D. Calligaro, MD, Jiah Jang, DO, Samuel C. Tyagi, MD, Nicholas J. Madden, DO, Douglas A. Troutman, DO, Matthew J. Dougherty, MD.
Pennsylvania Hospital, Philadelphia, PA, USA.
OBJECTIVES: Non-invasive diagnostic testing may be beneficial to identify stenotic (failing) stents placed for occlusive lower extremity peripheral arterial disease (LEPAD), especially if subsequent intervention proves useful in maintaining prolonged stent patency. The purpose of this study was to evaluate whether duplex ultrasonography (DU) can reliably diagnose failing bare metal stents placed in iliac, femoral and popliteal arteries for LEPAD. METHODS: Between January 1, 2013 - December 31, 2016, we placed 172 stents for LEPAD in 119 arterial segments (30 iliac, 89 femoro-popliteal) (1.4 stents/stenotic artery) in 110 patients who underwent > one DU surveillance study documenting stent patency. Mean treatment length was 7.0 cms (range, 2.0 - 21.0 cms). Post-stent DU surveillance was performed in our Inter-societal Accreditation Commission accredited non-invasive vascular lab at 1 week and then every 6 months thereafter. DU measured peak systolic velocities (PSVs) and ratio of adjacent PSVs (Vr) every 2.0 cms within the stent(s) and adjacent arteries. We retrospectively classified the following factors as "abnormal DU findings": focal PSVs > 300 cm/s, uniform PSVs < 45 cm/s, and Vr > 3.0. RESULTS: During average follow-up of 22 months (range, 1 week - 48 months), all three of these DU criteria were "normal" in 62 (52%) of the 119 stented segments. Of the other 57 (48%) stented arterial segments that had > 1 abnormal DU finding, 40 underwent prophylactic intervention, 12 occluded that did not undergo intervention (5 patient refusal, 4 surgeon decision, 3 shortened surveillance interval), and 5 remained patent after mean follow-up of 7.2 months. Therefore, of the 17 stented arterial segments with > one abnormal DU finding that did not undergo intervention, 12 (70%) went on to occlude vs. 2 of 62 (3%) with normal DU findings (p=0.0001)(sensitivity 71%, specificity 97%). Of these 12 stented arterial segments with abnormal DU findings that occluded, 7 had uniform low PSVs only, 3 had both abnormal PSV and Vr’s, and 2 had abnormal Vr’s only. CONCLUSIONS: DU surveillance can predict LEPAD stent thrombosis. Focal PSVs > 300 cms/s, Vr > 3.0, and most importantly, uniform PSVs < 45 cm/s throughout the stent were statistically reliable markers for predicting stent thrombosis, while the absence of any of these abnormalities strongly predicted stent patency.
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