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

OBJECTIVES The 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. BACKGROUND The clinical and prognostic value of post-exercise ABI in the setting of normal or abnormal resting ABI remains uncertain. METHODS A 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. RESULTS Compared 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. CONCLUSIONS Post-exercise ABI appears to offer both clinical (lower extremity revascularization) and prognostic information in those with normal and abnormal resting ABI.