Application of Cardiovascular Mechanics to Risk Stratification in End Stage Renal Disease

and left ventricular hypertrophy where a normal ejection fraction does not necessarily equate to normal contractile function. It is also more reproducible. As a measure of vascular stiffness, PWV is often regarded as a functional assessment of vascular aging, and has a longer track record than GLS. It is proven to be associated with cardiovascular outcomes across a range of conditions, but although it is included in the current European guidelines for the management of hypertension [5], it is less widely used in routine cardiology practice. Chui et al. [1] found that a more positive (more abnormal) GLS predicted cardiac death and major cardiac events but not all-cause mortality. However, the associations were not particularly strong and diabetes was a much stronger predictor of cardiac death than GLS. Age, increased PWV and indexed LV mass were the only predictors of all-cause mortality. At first sight, it is surprising that PWV predicted all-cause mortality but not cardiac mortality or major cardiac events, given its established predictive role in cardiac outcomes in end-stage kidney disease [6] . It is also perhaps surprising that the 2 parameters themselves demonstrated no association given the impact of aortic stiffness on ventricular loading and hence ventricular mechanics. Reduced (i.e. more positive) GLS reflects impairment of contraction of the subendocardial The study by Chiu et al. [1] examines 2 established non-invasive measures of cardiovascular mechanics in a population of patients undergoing maintenance haemodialysis. Global longitudinal strain (GLS) is a measure of myocardial deformation and pulse wave velocity (PWV) is a measure of aortic stiffness. Both GLS and PWV are recognised as predictors of mortality in end-stage kidney disease. Although not large (198 evaluable subjects) and restricted to a single centre, this is the largest series to combine both measures and it is worth emphasising that this was a high-risk population. Almost 40% were diabetic and more than a quarter had an existing diagnosis of coronary artery disease. GLS using speckle tracking echocardiography has an expanding role in cardiology practice and has proved to be superior to left ventricular ejection fraction (LVEF) in predicting outcomes in situations as diverse as sepsis [2] , heart failure with preserved ejection fraction [3] and late after cardiotoxic chemotherapy [4] . As such, it is part of the repertoire of many cardiology departments. Speckle tracking relies on reasonable greyscale echocardiographic image quality but has the attraction that analysis is semi-automated. The key to its superiority over LVEF is that it may be abnormal when LVEF is within range, especially in conditions associated with increased afterload Published online: April 12, 2016 Nephrology American Journal of