Exercise testing criteria to diagnose lower extremity peripheral artery disease assessed by computed-tomography angiography

Abstract

Background The sensitivity and specificity of exercise testing have never been studied simultaneously against an objective quantification of arterial stenosis. Aims were to define the sensitivity and specificity of several exercise tests to detect peripheral artery disease (PAD), and to assess whether or not defined criteria defined in patients suspected of having a PAD show a difference dependent on the resting ABI. Methods In this prospective study, consecutive patients with exertional limb pain referred to our vascular center were included. All patients had an ABI, a treadmill exercise-oximetry test, a second treadmill test (both 10% slope; 3.2km/h speed) with post-exercise pressures, and a computed-tomography-angiography (CTA). The receiver-operating-characteristic curve was used to define a cut-off point corresponding to the best area under the curve (AUC; [CI95%]) to detect arterial stenosis 50% as determined by the CTA. Results Sixty-three patients (61+/-11 years-old) were included. Similar AUCs from 0.72[0.63–0.79] to 0.83[0.75–0.89] were found for the different tests in the overall population. To detect arterial stenosis 50%, cut-off values of ABI, post-exercise ABI, post-exercise ABI decrease, post-exercise ankle pressure decrease, and distal delta from rest oxygen pressure (DROP) index were 0.91, 0.52, 43%, 20mmHg and -15mmHg, respectively (p<0.01). In the subset of patients with an ABI >0.91, cut-off values of post-exercise ABI decrease (AUC = 0.67[0.53–0.78]), and DROP (AUC = 0.67[0.53–0.78]) were 18.5%, and -15mmHg respectively (p<0.05). Conclusion Resting ABI is as accurate as exercise testing in patients with exertional limb pain. Specific exercise testing cut-off values should be used in patients with normal ABI to diagnose PAD.