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Background: Although the resting ankle-brachial index (ABI) is commonly used to diagnose peripheral artery disease (PAD), limited data suggest several indices measured after exercise may have increased sensitivity for identifying PAD. The aim of this study was to determine the utility of resting ABI and three post-exercise physiological parameters for diagnosing PAD confirmed by arterial imaging studies.
Methods: In this retrospective analysis, we reviewed consecutive exercise ABI studies performed at Brigham and Women's Hospital. Our final analysis included only those accompanied by lower extremity imaging (CT, MR, or invasive angiography) within one year without intervening lower extremity revascularization. We defined PAD as at least one lesion on imaging with a >75% stenosis as determined by blinded review. For each limb, we assessed the sensitivity and specificity for identifying PAD for resting ABI <0.9, exercise ABI <0.9, a drop in ABI greater than 20% with exercise (ABI20%), and a drop in ankle pressure greater than 30mmHg with exercise (ex30mmHg).
Results: Of the 199 studies that met our inclusion criteria, imaging showed PAD in at least one limb in 126 (63%). The majority of lesions were infrageniculate (38% right, 38% left) followed by femoral-popliteal (25% right, 25% left) and aorto-iliac (19% right, 16% left). Resting ABI <0.9 had sensitivities of 53% (right, p<0.001) and 46% (left, p=0.004). Exercise ABI <0.9 had sensitivities of 79% (right, p=0.008) and 75% (left, p=0.003). ABI20% had sensitivities of 59% (right, p=0.02) and 43% (left, p=0.23). Ex30mmHg had sensitivities of 3% (right, p=0.71) and 4% (left, p=1.00). For limbs with a normal resting ABI but PAD confirmed by imaging (n=59 right, n=67 left), exercise ABI yielded sensitivities of 58% (right) and 55% (left). Patient level analysis showed that the resting ABI identified 53% of subjects with PAD, and exercise ABI identified 80% of patients with PAD on imaging.
Conclusions: Exercise ABI correctly identified an additional 27% of patients with PAD compared to resting ABI. Furthermore, exercise ABI had added clinical utility in patients with normal resting ABIs and was superior to other exercise indices commonly used in practice.
Room 209 C
Saturday, March 18, 2017, 8:51 a.m.-9:01 a.m.
Session Title: Highlighted Original Research: Vascular Medicine and the Year in Review
Abstract Category: 40. Vascular Medicine: Non Coronary Arterial Disease
Presentation Number: 905-10
- 2017 American College of Cardiology Foundation