A common goal in society is to reduce the burden of atherosclerotic cardiovascular (CV) disease by risk assessment and individualized stepwise preventive treatment (1). One issue with this is to cost-effectively identify subjects at risk. A pathological ankle brachial index (ABI) is a well-known marker for groups with a risk for future CV events (2) and as an assessment tool ABI is considered simple but rather unspecific. ABI measurement guidelines include insonation of two ankle arteries per leg and using the higher pressure obtained for the ABI calculation(3), and the use of just one value have been tested in risk stratification models. We hypothesized that the use of all four ABI values in a subject could improve the validity of the ABI test as a CV risk predictor, and the aim of this study was to evaluate if the number of ankle arteries with ABI<0.9 was associated to the risk for long-term CV events.

ABI measurements were made in 5080 randomly selected citizens aged 60-90 years. ABI was calculated for the dorsal pedis and anterior tibial arteries in each leg. Subjects were defined to be references if all four ankle vessels had an ABI≥0.9. Remaining subjects were placed in four groups depending on the number of vessels with ABI <0.9. After ten-years of follow-up, CV morbidity data was extracted from mandatory Swedish national health registries. The Hazard ratio (HR) for CV events and the CV event free survival were then compared among the groups in a Cox proportional hazard regression model, adjusted for age.

A total of 4940 subjects were included in the cohort, of whom 83,8% were references, 5.8% had one affected vessel, 4.1% two, 1.7% three and 4.7% had all four vessels affected. The 10-years CV event free survival for references, and the groups with 1 to 4 affected vessels were 71.0%, 59.8% (one vessel), 48.2% (two), 47.1% (three) and 32.1% (four), respectively. The corresponding age adjusted HR (95% CI) for the composite outcome of all-cause mortality and a non-fatal CV event for the groups with 1 to 4 affected vessels were 1.3 (1.09 - 1.61), 1.84 (1.50 - 2.25), 1.81 (1.34-2.43) and 2.81 (2.36 - 3.35), respectively.

In subjects from a general elderly population, upcoming morbidity increases with the number of vessels assessed with an ABI<0.9. Accordingly, using of all four ankle pressures measured may improve the predictive accuracy of ABI in a risk stratification model. This needs to be tested in future studies.

1. Visseren FLJ, Mach F, Smulders YM, Carballo D, Koskinas KC, Bäck M, et al. 2021 ESC Guidelines on cardiovascular disease prevention in clinical practice. Eur Heart J. 2021;42(34):3227-337. 2. Bauersachs R, Debus S, Nehler M, Huelsebeck M, Balradj J, Bowrin K, et al. A Targeted Literature Review of the Disease Burden in Patients With Symptomatic Peripheral Artery Disease. Angiology. 2020;71(4):303-14. 3. Aboyans V, Ricco JB, Bartelink MEL, Bjorck M, Brodmann M, Cohnert T, et al. 2017 ESC Guidelines on the Diagnosis and Treatment of Peripheral Arterial Diseases, in collaboration with the European Society for Vascular Surgery (ESVS): Document covering atherosclerotic disease of extracranial carotid and vertebral, mesenteric, renal, upper and lower extremity arteriesEndorsed by: the European Stroke Organization (ESO)The Task Force for the Diagnosis and Treatment of Peripheral Arterial Diseases of the European Society of Cardiology (ESC) and of the European Society for Vascular Surgery (ESVS). Eur Heart J. 2017.