Abstract
ObjectivesThe ankle brachial index (ABI) can be used to diagnose peripheral arterial disease (PAD). The clinical relevance of the ABI, especially in patients with known clinically manifest cardiovascular disease (CVD), is unknown. The authors set out to investigate the relationship between a screen-detected ABI and the risk for future cardiovascular morbidity and mortality in patients with clinically manifest CVD.Design, materials and methodsPatients with clinically manifest CVD were selected from the UCC-SMART cohort (n = 8360) and divided into four groups: normal ABI (0.91–1.39), screen-detected low ABI ≤ 0.9, screen-detected high ABI ≥ 1.4, and patients with known PAD irrespective of their ABI. Adjusted Cox Proportional Hazard Ratios (HRs) for Major Adverse Cardiovascular Events (MACE), Major Adverse Limb Events (MALE), and all-cause mortality were calculated. In addition, stratified analyses for women and men and for the presence of diabetes were performed.ResultsDuring a median follow-up of 8.3 years (IQR 7.7) 1646 MACE, 601 MALE and 1958 all-cause mortalities were observed. Compared with normal ABI patients, patients with a screen-detected low ABI and patients with manifest PAD had a higher risk of MACE, MALE, and all-cause mortality with HRs of 1.9 (95% CI 1.6–2.2) for MACE, 7.6 (95% CI 5.7–10.1) for MALE, 1.7 (95% CI 1.5–2.0) for mortality and 1.3 (95% CI 1.2–1.5) for MACE, 13.8 (95% CI 11.1–17.1) for MALE, 1.7 (95% CI 1.5–1.9) for mortality, respectively. Screen-detected high ABI did not increase the risk of either MACE or MALE, however, was associated with lower risk of all-cause mortality with a HR of 0.6 (95% CI 0.5–0.9). Stratified analyses for women & men and for diabetes status were comparable for all three outcomes.ConclusionsIn patients with manifest CVD but without PAD, a screen-detected low ABI is a powerful risk indicator for cardiovascular events, limb events, and all-cause mortality.
Highlights
The ankle brachial index (ABI) is a fast, easy to perform and non-invasive method to diagnose peripheral arterial disease (PAD)
Compared with normal ABI patients, patients with a screen-detected low ABI and patients with manifest PAD had a higher risk of Major Adverse Cardiovascular Events (MACE), Major Adverse Limb Events (MALE), and all-cause mortality with Hazard Ratio (HR) of 1.9 for MACE, 7.6 for MALE, 1.7 for mortality and 1.3 for MACE, 13.8 for MALE, 1.7 for mortality, respectively
A low ABI is indicative of severe atherosclerosis of the lower extremity arteries and studies, on specific patient populations such as patients with stroke or undergoing CABG, showed that an asymptomatic low ABI score is a strong predictor for future cardiovascular events such as stroke (1.4–5.2), myocardial infarction (2.1–2.4), and mortality (1.6–2.1) [1–6]
Summary
The ankle brachial index (ABI) is a fast, easy to perform and non-invasive method to diagnose peripheral arterial disease (PAD). The ABI is usually calculated by dividing the systolic blood pressure of the tibial or dorsalis artery by the systolic blood pressure of the brachial artery. Besides its’ use as a diagnostic tool, an abnormal ABI has been studied as a risk predictor for cardiovascular morbidity and mortality [1–6]. A low ABI is indicative of severe atherosclerosis of the lower extremity arteries and studies, on specific patient populations such as patients with stroke or undergoing CABG, showed that an asymptomatic low ABI score is a strong predictor for future cardiovascular events such as stroke (1.4–5.2), myocardial infarction (2.1–2.4), and mortality (1.6–2.1) [1–6]. High ABI measurements are commonly thought to be indicative of medial arterial calcification (MAC) and/or arterial stiffening and are usually seen in patients with diabetes mellitus (DM), renal failure or the elderly [7–11]. Inconsistent results have been published on the relationship between a high ABI and the risk of future cardiovascular events, with some studies reporting an increased risk [7, 8, 12, 13] and other studies reporting no significant increase in risk [9, 14–16]
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