Doppler-based diagnosis of restenosis after femoropopliteal percutaneous transluminal angioplasty: Sensitivity and specificity of the ankle/brachial pressure index versus changes in absolute pressure values

The aim of this study was to investigate the sensitivity and specificity of changes of the ankle/brachial pressure index (ABI) and changes in absolute ankle pressure values to detect restenosis in patients who underwent femor opopliteal percutaneous transluminal angioplasty (PTA). In total, 171 patients were followed up prospectively for 12 months; sensit ivity and specificity of Doppler-based diagnosis were calculated with duple x scanning as the gold standard. The criteria for restenosis were: (1) a lo ss of 50% of the ABI increase or (2) loss of 50% of the absolute ankle syst olic pressure, gained by PTA. For both criteria, different cut-off points ( minimum increase of ABI or ankle pressure gained by PTA) were evaluated. The overall sensitivity and specificity of the ABI criterion was 67% and 80 %, respectively. The introduction of cut-off points (the minimum ABI increa se gained by PTA), ranging between greater than or equal to 0.13 and greate r than or equal to 0.35, did not markedly improve the results. The overall sensitivity and specificity of the absolute ankle pressure criterion again was poor (59% and 81%). With the introduction of cut-off points (the minimu m increase of absolute ankle pressure gained by PTA) ranging between greate r than or equal to 15 mm Hg and greater than or equal to 20 mm Hg, the sens itivity and specificity of the criterion improved to acceptable 92% and 96% , respectively. It is concluded, that in the long-term follow-up of PTA patients, the "loss of 50% ankle pressure" criterion will detect restenosis with reasonable ac curacy in those patients, in whom an increase in systolic ankle pressure gr eater than or equal to 20 mm Hg is warranted.