Abstract

As central (aortic) blood pressures and augmentation indices predict cardiovascular outcomes beyond brachial blood pressures, there is growing clinical interest in the measurement of central haemodynamics. However, before these measurements can be implemented in clinical practice, determination of normal reference values is mandatory. A rigorous step-wise process is required to define accurate thresholds, so that misdiagnosis, inappropriate initiation of pharmacological therapy and unnecessary additional costs can be prevented. To-date there are limited data: age-specific thresholds have been defined using 95% prediction bands (4 studies); mean plus 2 standard deviation (2 studies) and 95th percentile (1 study) threshold values have been provided; and normative reference equations have been generated (3 studies), with only one study proving a means to estimate values above the normative population mean. There is lack of consistency in the thresholds defined in these studies, which indicates that we are far from achieving consensus even on the first step of the process. It is possible that different thresholds for central blood pressures may be required for measurement devices that differ in their technology and techniques. We recommend that experts in the field convene a consensus working group to resolve the controversies and plan a way forward. Importantly, thresholds would need to be confirmed in population studies; their utility in predicting cardiovascular risk and target organ changes tested and validated in prospective outcome-based studies; and their efficacy in diagnosis and treatment assessed in intervention studies.

Keywords: Central blood pressure, central augmentation index, pulse pressure, thresholds, normal reference values, hypertension, brachial blood pressures, cardiovascular risk factors