Prognostic significance of declining ankle-brachial index values in patients with suspected or known peripheral arterial disease.

Background: Peripheral arterial disease (PAD) is a risk factor for cardiovascular events. This study assessed the prognostic significance of repeated ankle-brachial index (ABI) measurements at rest and after exercise in patients with PAD receiving conservative treatment.

Methods: In a cohort study of 606 patients (mean age 62+/-12 years, 68% male), ABI at rest and after exercise was measured at baseline and after 1 year. Patients with reductions in ABI were divided into three equally-sized groups (minor, intermediate and major reductions) and were compared to patients without reductions. During a mean follow-up of 5+/-3 years, all-cause mortality, cardiac events, stroke and progression to kidney failure were noted.

Results: Death was recorded in 83 patients (14%) of which 49% were due to cardiac causes. Non-fatal myocardial infarction occurred in 38 patients (6%), stroke in 46 (8%) and progression to kidney failure in 35 (6%). By multivariate analysis, patients with major declines in resting (>20%) and post-exercise (>30%) ABI were at increased risk of all-cause mortality (HR: 3.3, 95% CI: 1.5-7.2, HR: 3.0, 95% CI: 1.4-6.4, respectively), cardiac events (HR: 3.1, 95% CI: 1.3-7.2, HR: 2.4, 95% CI: 1.1-5.6, respectively), stroke (HR: 4.2, 95% CI: 1.6-10.4, HR: 3.9, 95% CI: 1.4-10.2, respectively) and kidney failure (HR: 2.7, 95% CI: 1.1-7.5, HR: 6.9, 95% CI: 1.5-31.5, respectively), compared to patients with no declines in ABI.

Conclusions: This study shows that major 1-year declines in resting and post-exercise ABI are associated with all-cause mortality, cardiac events, stroke and kidney failure in patients with PAD.