Heterogeneity of Ankle-Brachial Indices in Patients Undergoing Revascularization for Critical Limb Ischemia

Abstract

Objectives: This study sought to describe the distribution of pre-intervention treated-limb ankle-brachial indices (ABIs) among patients with critical limb ischemia (CLI) undergoing percutaneous vascular intervention (PVI) or surgical revascularization (SR).

Background: CLI is diagnosed by the presence of rest pain, tissue ulceration, or gangrene due to chronic arterial insufficiency. It is unclear what fraction of patients with suspected CLI have severe peripheral artery disease (PAD) on noninvasive functional testing.

Methods: The study included patients who underwent lower extremity revascularization for CLI in a multicenter registry in Michigan from January 2012 through June 2015. ABIs were classified as normal (ABI: 0.91 to 1.40), mild-moderate (ABI: 0.41 to 0.90), and severe (ABI: ≤0.40). Pre- and post-intervention Peripheral Artery Questionnaire summary scores were assessed in a subset of patients.

Results: Among 10,756 patients with signs or symptoms of CLI, 9,113 (84.7%) underwent PVI and 1,643 (15.3%) underwent SR. ABIs were recorded in 4,972 (54.6%) PVI and 1,012 (61.6%) SR patients. Patients undergoing PVI had higher ABIs than those undergoing SR, with substantial variation in both groups (PVI: 0.72 ± 0.29 vs. SR: 0.61 ± 0.29; p < 0.001). Nearly a quarter of patients with compressible arteries had normal ABIs (24.0%), whereas severe PAD was uncommon (16.5%). A significant improvement in Peripheral Artery Questionnaire scores was noted after intervention across all ABI categories.

Conclusions: Among patients undergoing revascularization for CLI in contemporary practice, the authors found substantial heterogeneity in pre-intervention ABIs. The disconnect between ABI results and clinical diagnosis calls into question the utility of ABIs in this population and suggests the need for standardization of functional PAD testing.

Keywords: ankle-brachial index; critical limb ischemia; percutaneous vascular intervention; peripheral artery disease; surgical bypass graft.

Figure 1:. Distribution of ankle-brachial indices by mode of revascularization.

The probability density function for ABI results for patients undergoing percutaneous vascular intervention or surgical revascularization for critical limb ischemia are demonstrated by the solid black and dashed red lines, respectively. The dashed vertical red line indicates the mean ABI for surgical revascularization (mean±SD: 0.61±0.29), whereas the solid black line indicates the mean ABI for PVI (0.72±0.29). Abbreviations: ABI = ankle-brachial index; PVI = peripheral vascular intervention.

Figure 2:. Pre- and post-intervention peripheral artery questionnaire summary scores by mode of revascularization.

Pre-intervention and post-intervention Peripheral Artery Questionnaire (PAQ) summary scores are demonstrated for patients undergoing percutaneous vascular intervention (A) and surgical revascularization (B). Patients who underwent percutaneous vascular intervention had 6-month post-intervention PAQ scores collected, whereas those who underwent surgical revascularization had 1-year post-intervention PAQ scores collected. Abbreviations: PAQ = Peripheral Artery Questionnaire. * All pre- and post-intervention differences are statistically significant at P<0.001.

Central Illustration:. Heterogeneity of pre-intervention ankle-brachial indices among patients undergoing revascularization for critical limb ischemia.

Frequency of normal, mild-moderate, and severe pre-intervention treated limb ankle-brachial index results among patients with compressible arteries undergoing percutaneous vascular intervention or surgical revascularization for treatment of critical limb ischemia.