Determining criteria for predicting stenosis with ultrasound duplex after endovascular intervention in infrainguinal lesions.

Background: Studies examining duplex surveillance of lower extremity bypass grafts have defined a role for guiding graft re-intervention. The goal of this study is to determine the utility of duplex scanning to detect angiographic restenosis after endovascular therapy in patients with infrainguinal arterial disease.

Methods: A prospective registry including all patients treated for lower extremity atherosclerotic disease between February 2004 and September 2008 was established. Patients were followed up with duplex ultrasound at 1, 3, 6, 12 months, and then annually. Patients receiving repeat angiograms were identified and angiogram and duplex data were abstracted. Velocity ratios (Vr) were calculated for each lesion by dividing the peak velocity within the lesion by the peak velocity proximal to the lesion. Logarithmic regression and receiver operator characteristic (ROC) curve analyses were used.

Results: Repeat angiograms were performed on 345 lesions in 143 patients, and 254 lesions in 103 patients had a corresponding duplex ultrasound. Indications for the initial intervention were claudication (n = 62, 43.4%), rest pain (n = 23, 16.1%), and tissue loss (n = 58, 40.5%). A total of 178 superficial femoral artery (SFA) lesions, 59 popliteal lesions, and 17 tibial lesions were identified by surveillance duplex in 103 patients. In all, 70.5% of the intervened vessels that were studied were nonstented and the remaining 29.5% were stented. A total of 65% of the patients had diabetes. On determining correlations for peak systolic velocity (PSV) as measured by duplex ultrasound with degree of angiographic stenosis, strong correlation coefficients for SFA disease (R² = 0.84) and popliteal disease (R² = 0.88) were found. However, poor correlation was found in patients with tibial disease. When analyzing the lesions on the basis of Vr < 2.0, 11 of 86 (12.8%) had >70% angiographic stenosis. In lesions with ratios from 2 to 2.5, 12 of 13 (92.3%) had >70% angiographic stenosis and in lesions with ratios >2.5, 69 of 75 (92.0%) had >70% angiographic stenosis. ROC curve analysis showed that to detect ≥ 70% stenosis in the SFA, a PSV ≥ 204 cm/sec had a sensitivity of 97.6% and specificity of 94.7%. To detect ≥ 70% stenosis in the overall femoropopliteal region, a PSV ≥ 223 cm/sec had a sensitivity of 94.1% and specificity of 95.2%.

Conclusions: Duplex ultrasound surveillance correlates to the degree of angiographic stenosis on the basis of PSV in the SFA and popliteal region. Correlation in the tibial vessels is poor. Vr > 2.0 appear to correlate to angiographic stenosis of > 70%. ROC analysis shows that PSV can have sufficiently high sensitivity and specificity to predict angiographic stenosis in the femoropopliteal region.