Bicycle Testing as an Alternative Diagnostic Tool in Patients Suspected of Intermittent Claudication

Background: The ankle-brachial index (ABI) obtained after a treadmill challenge is often used to confirm the diagnosis of intermittent claudication (IC). However, some patients fail treadmill testing due to (temporary) orthopedic or neurologic comorbidity or fear of falling. The aim of this study was to evaluate the role of bicycle testing as an alternative for treadmill testing. It was hypothesized that ABIs obtained after bicycle tests were not different compared with values after standard treadmill testing. Methods: In this validation study, newly diagnosed IC patients (Rutherford 1-3) underwent a standard treadmill test (TT, "gold standard") and two bicycle protocols, one with a continuous resistance submaximal character (submaximal bicycle test, SBT) and a second with an incremental ramp form having a maximal character (maximal bicycle test, MBT). ABIs of both legs were obtained before and twice after each of these three different exercise tests. Healthy individuals matched for age and gender served as controls. Results: The study population consisted of 32 patients (68 +/- 11 years, 21 men). ABIs of each leg (n = 64) obtained after TT correlated significantly with values obtained after either bicycle test (TT vs. SBT: r = 0.90, P < 0.001; TT vs. MBT: r = 0.88, P < 0.001). Drops in ABI after both types of exercise were significantly correlated (TT vs. SBT: r = 0.66, P < 0.001; TT vs. MBT: r = 0.32, P < 0.01). A 98% sensitivity and 86% specificity for diagnosis of IC was observed after the SBT. After the MBT, these values were 98% and 43%, respectively. Healthy controls (n = 13) demonstrated ABI values >0.9 after cycling in all tests. Conclusions: Both submaximal and a maximal bicycle tests may serve as alternative noninvasive tools for detecting intermittent claudication. Bicycle tests can potentially be used for patients unable to perform a treadmill test.