Non-invasive measurements of arterial function: What? When? Why should we use them?

Cardiovascular (CV) disease remains the leading cause of deaths worldwide, accounting for 32% of global deaths (1). CV mortality reduction is a key focus of the United Nations Healthy Strategy (2) but in order to achieve this, there is a need to improve risk stratification (3, 4). Nearly half of all CV deaths are attributable to coronary artery disease (CAD) (1). Current risk stratification for suspected CAD uses a pre-test probability (PTP) based on the nature of chest pain, gender and age to decide on the subsequent intervention. In those with low PTP for CAD, the Framingham Risk Score (FRS) (5) discriminates the risk of CV events well for subsequent primary prevention (6). Individuals with a high PTP can reach a diagnosis of CAD and proceed to optimal medical therapy or invasive coronary angiography depending on symptom severity (5). There is a large group of individuals with intermediate PTP who proceed to further investigations with coronary imaging or stress testing (5), however a positive stress test only identifies less than half (7, 8) whilst coronary imaging defines less than a third of those who develop a subsequently develop a CV event (5, 7). Therefore, risk stratification with additional assessments may be beneficial. Measures of arterial stiffness and endothelial function provide global measures of arterial health. In this review, we focus on arterial stiffness measured by pulse wave velocity (PWV), arterial wave reflections by augmentation index (AIx) and endothelial function measured by either flow-mediated dilatation (FMD), forearm blood flow or digital reactive hyperaemia.Non