Exercise ankle brachial index adds important prognostic information on long-term out-come only in patients with a normal resting ankle brachial index

Abstract

Background: The clinical value of exercise ankle brachial index (ABI) is still unclear, especially in patients with normal resting ABI.

Method: 2164 patients performed a single-stage treadmill exercise test to diagnose or evaluate PAD. The population was divided into two groups: a normal resting ABI (resting ABI≥0.90) and PAD (resting ABI<0.90). Patients with a normal resting ABI were divided into 4 exercise ABI groups: exercise ABI<0.90, 0.90-0.99, 1.00-1.09 and 1.10-1.29 (reference).

Results: Mean follow-up was 5 years. Exercise ABI added significant prognostic information on all cause long-term mortality only in patients with normal resting ABI (p-value 0.014, HR 0.99 95% CI (0.98-0.99)), not in patients with PAD. Fifty years or older (OR 2.93 95% CI (1.65-5.20)) and resting systolic blood pressure>140 mmHg (OR 2.18 95% CI (1.35-3.55)) were associated with an abnormal exercise ABI in patients with a normal resting ABI. Mortality rate increased when the exercise ABI became worse (p trend 0.0001) with a 2.5-fold increase mortality risk in patients with a normal resting ABI but exercise ABI <0.90 (HR 2.56, 95% CI (1.11-5.91)).

Conclusion: In patients with a normal resting ABI, treadmill exercise ABI added important prognostic information on long-term mortality. Based on our results we recommend that at least all patients suspected for PAD, with a resting ABI≥0.90, who are 50 years or older and having hypertension should undergo treadmill exercise testing.