Peripheral artery disease, abnormal ankle-brachial index, and prognosis in patients with acute coronary syndrome

Abstract

Objectives: Ankle-brachial index (ABI) is an independent prognostic marker of cardiovascular events among patients with coronary artery disease (CAD). We aimed to investigate the outcome of patients hospitalized with acute coronary syndrome (ACS) and abnormal ABI.

Approach and results: ABI was prospectively measured in 1,047 patients hospitalized due to ACS, who were stratified into three groups, namely, those with clinical peripheral artery disease (PAD) (N = 132), those without clinical PAD but with abnormal (< 0.9) ABI (subclinical PAD; N = 148), and those without clinical PAD with normal ABI (no PAD; N = 767). Patients were prospectively followed for 30-day major adverse cardiovascular event (MACE) and 1-year all-cause mortality. The mean age was 64 years. There was a significant gradual increase throughout the three groups in age, i.e., the incidence of prior stroke, diabetes mellitus, and hypertension (p for trend = 0.001 for all). The in-hospital course showed a gradual rise in the incidence of complications with an increase in heart failure [2.5, 6.1, and 9.2%, (p for trend = 0.001)] and acute kidney injury [2, 4.1, and 11.5%, (p for trend = 0.001)]. At day 30, there was a stepwise increase in MACE, such that patients without PAD had the lowest rate, followed by subclinical and clinical PADs (3.5, 6.8, and 8.1%, respectively, p for trend = 0.009). Similarly, there was a significant increase in 1-year mortality from 3.4% in patients without PAD, through 6.8% in those with subclinical PAD, to 15.2% in those with clinical PAD (p for trend = 0.001).

Conclusion: Subclinical PAD is associated with poor outcomes in patients with ACS, suggesting that routine ABI screening could carry important prognostic significance in these patients regardless of PAD symptoms.

Keywords: acute coronary syndrome; ankle brachial blood pressure index; claudication; peripheral arterial disease (PAD); peripheral vascular disease; vascular disease (PVD).

FIGURE 1

In-hospital course. The figure demonstrates the frequency of in-hospital complications according to the pre-specified groups. The chi-square test for trend was used. AKI, acute kidney injury; MR, mitral regurgitation; PAD, peripheral arterial disease; TIA, transient ischemic attack.

FIGURE 2

A 30-day MACE, individual components, and bleeding according to pre-specified groups: no-PAD (green), subclinical PAD (orange), and clinical PAD (blue). MACE, major adverse cardiovascular event.

FIGURE 3

One-year mortality. The figure demonstrates the frequency of 1-year mortality according to the pre-specified groups: no-PAD (green), subclinical PAD (orange), and clinical PAD (blue). The chi-square test for trend was used. PAD, peripheral arterial disease.

FIGURE 4

Multivariable Cox proportional hazard model for 1-year mortality (95%CI). Baseline characteristics (p < 0.05 for comparison between the groups of clinical PAD or no PAD with pathological ABI, vs. no PAD with non-pathological ABI) were chosen as covariates. Model’s data contain only patients with non-missing values in these variables, N = 1,035 patients.

FIGURE 5

(A) Univariable Cox proportional hazard models for 17-months (maximal follow-up time) all-cause mortality according to ABI value. The figure demonstrates the difference in mortality according to ankle-brachial index cutoff points. N in each model (shown in parenthesis) regards to the number of patients with ABI less than 1, 0.9, 0.8, and 0.7 accordingly. ABI, ankle-brachial index. (B) Overall mortality according to ABI groups. ABI, ankle-brachial index.