Measurement of Achilles tendon thickness using ultrasonography for diagnosis and risk assessment in patients with familial hypercholesterolemia

Familial hypercholesterolemia (FH) is an autosomal dominant inherited disorder characterized by elevated low-density lipoprotein cholesterol (LDL-C) levels and skin and/or tendon xanthomas. FH is caused by mutations in genes associated with the LDL receptor pathway. Heterozygous FH is frequently encountered, occurring in about one in 300 people, one in 30 people with coronary artery disease, and one in 15 people with premature coronary artery disease or severe hyperlipidemia. Because FH patients are exposed to high LDL-C concentrations from birth, this leads to progressive atherosclerosis, and the development of cardiovascular events in these patients is 15-20 years younger than the typical age of onset. Achilles tendon thickening is the most specific physical finding in FH, although it is also observed in patients with metabolic diseases such as sitosterolemia and cerebral tendon xanthomatosis and in cases of Achilles tendon rupture. In Japan, FH criteria include Achilles tendon thickening as a diagnostic criterion in addition to the presence of tendon xanthomas. Furthermore, thicker Achilles tendons are associated with a higher risk of cardiovascular events. Therefore, the measurement of Achilles tendon thickness is beneficial not only for the diagnosis of FH but also for cardiovascular event risk assessment. It is hoped that the measurement of Achilles tendon thickness will improve diagnostic performance and lead to earlier diagnosis and reduced incidence of coronary artery disease. This review summarizes the usefulness of measuring Achilles tendon thickness for diagnosis and risk assessment of cardiovascular events in FH.