Arterial Stiffness as Surrogate End Point

C lassic risk scores may underestimate the risk of cardio- vascular (CV) events in specific risk groups suitable for primary prevention, such as asymptomatic hypertensive subjects.1 Particularly, those considered as at intermediate risk may benefit the most from a reassessment of their CV risk using novel biomarkers. 2 In primary prevention, some imaging biomarkers, such as arterial stiffness, enhance risk prediction to a higher extent than circulating biomarkers.3 Whether novel biomarkers are ready for routine clinical use is a matter of controversy.1234 Particularly, whether an imaging biomarker can be substituted to clinical events in outcome trials and be considered as surrogate end point has rarely been demonstrated.1234 The aims of the present Brief Review are to address the concepts of "imaging biomarker" and "surrogate end point"; to focus on arterial stiffness as putative surrogate end point for future CV events; and to suggest additional studies to demonstrate its value as surrogate end point.Particularly, we will discuss experimental designs of randomized clinical trials demonstrating that a therapeutic strategy that normalizes arterial stiffness is more effective in preventing CV events than usual care."Circulating" Biomarkers Versus "Tissue" or "Imaging" Biomarkers