The Effect of Post-Exercise Ankle-Brachial Index on Lower Extremity Revascularization

ObjectivesThe purpose of this study was to investigate the effect of post-exercise ankle-brachial index (ABI) on the incidence of lower extremity (LE) revascularization, cardiovascular outcomes, and all-cause mortality in patients with normal and abnormal resting ABI.BackgroundThe clinical and prognostic value of post-exercise ABI in the setting of normal or abnormal resting ABI remains uncertain.MethodsA total of 2,791 consecutive patients with ABI testing between September 2005 and January 2010 were classified into group 1: normal resting (NR)/normal post-exercise (NE); group 2: NR/abnormal post-exercise (AE); group 3: abnormal resting (AR)/NE; and group 4: AR/AE. Abnormal post-exercise ABI was defined as a drop of >20% from resting ABI as per the American College of Cardiology/American Heart Association guidelines. The primary endpoint was incidence of LE revascularization. Secondary endpoints were major adverse cardiovascular events (MACE) and all-cause mortality. Associations between post-exercise ABI and outcomes were adjusted using multivariable Cox proportional hazard and propensity analyses.ResultsCompared with group 1 (NR/NE), group 2 (NR/AE) had increased LE revascularization (propensity-matched adjusted hazard ratio [HR]: 6.63, 95% confidence interval [CI]: 3.13 to 14.04; p < 0.001) but no differences in MACE or all-cause mortality. When resting ABI was abnormal, group 4 (AR/AE) compared with group 3 (AR/NE), abnormal post-exercise ABI was still associated with increased LE revascularization (adjusted HR: 1.59, 95% CI: 1.11 to 2.28; p = 0.01), which persisted after propensity matching (adjusted HR: 2.32, 95% CI: 1.52 to 3.54; p < 0.001). Compared with group 1 (NR/NE) and after propensity matching, group 4 (AR/AE) had a significant increase in MACE (adjusted HR: 1.44, 95% CI: 1.09 to 1.90; p = 0.009) and a trend toward increased all-cause mortality (adjusted HR: 1.37, 95% CI: 0.99 to 1.88; p = 0.052); however, group 3 (AR/NE) did not.ConclusionsPost-exercise ABI appears to offer both clinical (lower extremity revascularization) and prognostic information in those with normal and abnormal resting ABI.