Abstract Body: Resting ankle-brachial index (ABI) is widely used for noninvasive detection of peripheral arterial disease (PAD), yet its ability to identify hemodynamically significant disease is limited, especially in those with poorly compressible vessels. Heel-toe weight-bearing provocation is a low-cost alternative to treadmill-exercise testing that can unmask occult perfusion deficits. This study evaluated the diagnostic reliability of heel-toe provocative ABI in detecting clinically significant PAD and compared its discriminative value with established clinical risk factors, including coronary artery disease (CAD) and hypertension (HTN).

We hypothesize that heel-toe provocative ABI is an independent predictor of moderate PAD severity.

We conducted a retrospective cohort study of 476 patients with moderate arterial stenosis (50–74% occlusion) who underwent resting and heel-toe provocative ABI testing. Lower-extremity arterial duplex ultrasonography was the reference standard for PAD diagnosis. Diagnostic performance was evaluated using (1) immediate or 2-minute post-provocation ABI <0.90 and (2) ABI decline >20%. Sensitivity, specificity, positive and negative predictive values (PPV and NPV), and area under the curve (AUC) were calculated with 95% confidence intervals (CI). Multivariable logistic regression was used to identify independent predictors of duplex-confirmed stenosis, with demographic and clinical data obtained through deidentified chart review.

Two-minute post-provocation ABI was significantly predictive of moderate PAD severity (OR 0.55 per 10-mmHg decrement, p=0.049) whereas immediate post-provocation ABI was not (OR 0.93 per 10-mmHg decrement, p=0.797). The final model showed excellent discrimination (AUC 0.87) with appropriate calibration given CAD (OR 1.99, p=0.016) and HTN (OR 2.79, p=0.033) both independently predictive. Two-minute post-provocation ABI had a sensitivity of 68.6%, specificity of 81.8%, PPV of 51.4%, and NPV of 90.3% in evaluating moderate PAD severity.

Traditional risk factors for PAD, including HTN and CAD, remained independent predictors of moderate PAD. Two-minute post-provocative ABI measurements identified hemodynamically significant PAD more effectively than immediate post-exercise values. In conclusion, this model's strong discriminatory performance and concordance with well-studied risk factors supports the clinical utility of 2-minute post-provocation ABI as a simple, low-cost adjunct to resting ABI in assessing PAD severity.