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. 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 to values after standard treadmill testing.
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). ABI of both legs were obtained prior to and twice after each of these three different exercise tests. Healthy individuals matched for age and gender served as controls.
The study population consisted of 32 patients (age 68±11, 21 male). 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 a 86% specificity for the diagnosis IC was observed after SBT. After MBT, these values were 98% and 43%, respectively. Healthy controls (n=13) always demonstrated ABI values >0.9 after cycling.
Both a submaximal and a maximal bicycle test may serve as an alternative noninvasive tool for detecting intermittent claudication. Bicycle tests may potentially be used in patients unable to perform a treadmill test.