Introduction: Percutaneous transluminal angioplasty (PTA) is accepted for the treatment of patients with severe, disabling claudication who fail conservative management and also for patients with limb threatening ischaemia [1-5, 18, 20]. The development of neointimal hyperplasia (predominantly during the first 6-12 months after PTA), and the progression of the underlying atherosclerotic disease (thereafter), are the reasons of restenosis and reocclusion [1-4, 6]. More than 50% of occurring restenoses are primarily oligo/asymptomatic [1-4, 6-10, 25, 26]. Follow-up visits are aimed at detecting significant restenoses, before reocclusion occurs, so that timely reintervention is possible. In asymptomatic patients in whom reintervention is not necessary, repeated angiography is not justifiable. Non-invasive alternatives include Duplex scanning or the assessment of simple peripheral haemodynamic variables such as ankle systolic pressures and the ankle/brachial pressure index (ABI). The aim of this study was: (1) To determine the sensitivity and specificity of post PTA changes in the ABI, and changes in the absolute ankle pressure to detect restenoses after femoropopliteal PTA (as a gold standard, Duplex scanning, with its reported high sensitivity, specificity and accuracy for detecting restenosis was chosen [9, 25]. (2) For both methods, to evaluate the criteria (minimal magnitude of change-cut off points) necessary to detect restenosis with reasonable reliability. (3) To compare the diagnostic value of changes in ABI to changes in absolute ankle pressure, and to determine the method of preference for detection of post-PTA restenosis.
Material and methods: The study included 171 consecutive patients with peripheral arterial occlusive disease, Fontaine stage II or stage III, selected for femoro-popliteal PTA. All pts presented with single or multiple arterial stenoses or occlusions not exceeding 10 cm of length within the femoro-popliteal segment. At least one lower leg artery had to be patent. Only pts in whom PTA was successful (maximum residual lesion within the dilated segment showed < or = 30% diameter reduction (DR)) were accepted for a 12-month follow-up. After PTA all patients were prescribed a platelet aggregation inhibitor. The investigational scheme included the following procedures: 1. Duplex scanning of the entire lower leg vascular tree before PTA, within 7 days after PTA as well as at 4 weeks and at 12 months. 2. Scoring of Duplex results using the Bollinger angiography score system [11] which distinguishes the pelvic segment, a proximal and a distal superficial femoral segment, the popliteal artery including the popliteal trifurcation and the proximal 1/3 of the lower leg arteries. The score system allows the differentiation of single and multiple plaque (< or = 25% DR), single or multiple stenoses (< or = 50% and < or = 50% DR) involving less or more than 50% of the segment under investigation as well as short (< 50% of segment length) and long (> or = 50% of segment length) vascular occlusions. 3. The assessment of the resting ankle systolic pressures (dorsalis pedis artery, posterior tibial artery) of the reference leg, pre PTA, at 4 weeks, and 3, 6, 9 and 12 months using a 8 Mhz CW Doppler device (Parks 908) with the patient in the supine position and after a resting period of > or = 30 minutes. 4. The calculation of the ankle/brachial pressure index (ABI) as the ratio of the higher systolic pressure value from either the posterior tibial or the dorsalis pedis artery divided by the higher value of the two (bilateral) systolic brachial pressures. 5. A full physical examination including a pulse status, vascular auscultation as well as the assessment of the clinical symptomatology pre PTA, at 4 weeks as well as at 6 and 12 months. The following findings were suggestive of restenosis/reocclusion of the dilated segment. 1. Reoccurrence of a stenosis < or = 50% DR within the dilated segment and/or its inflow or outflo