Arterial stiffness as an imaging biomarker: are all pathways equal?

See related article, pp 161–167 The measurement of arterial stiffness is increasingly popular among physicians and researchers mainly because its predictive value for cardiovascular (CV) events has been well demonstrated. The largest amount of evidence has been given for aortic stiffness, measured through carotid-femoral pulse wave velocity (cfPWV). This has been initially reported in the late 1990s or early 2000s.1 Currently, as many as 19 studies consistently showed the predictive value of aortic stiffness for fatal and nonfatal CV events in various populations having different levels of CV risk: general population, patients with hypertension, elderly subjects, patients with type 2 diabetes mellitus, and patients with end-stage renal disease. In a recent meta-analysis,2 17 longitudinal studies totalizing 15 877 subjects with a mean follow-up of 7.7 years showed, for 1 SD increase in PWV, a risk ratio of 1.47 (1.31–1.64) for total mortality, 1.47 (1.29–1.66) for CV mortality, and 1.42 (1.29–1.58) for all-cause mortality. To be considered as a novel risk marker, arterial stiffness should add predictive information to established, standard risk markers, particularly the Framingham Risk Score or the European SCORE. This has been demonstrated with cfPWV in ≥3 studies: in patients with hypertension,3 in elderly subjects from a general population,4 and in middle-aged subjects from a general population.5 Another important requirement is that the measurement of the novel risk marker changes predicted risk sufficiently to change recommended therapy. This is indeed the case because several studies showed that a substantial amount of patients at intermediate risk could be reclassified into a higher or a lower CV risk, when arterial stiffness was measured.4–6 Aortic stiffness, measured through cfPWV, can thus be considered as a novel imaging biomarker for predicting CV events, although its value as a true surrogate end point requires a large intervention …