Modern clinical practice stresses the importance of basing healthcare practices and health policy on the best available clinical evidence. However, it is a long journey to translate research evidence into routine clinical practice through closing fundamental translational gaps. There have been numerous studies and meta-analyses demonstrating the prognostic value of arterial stiffness beyond established CVD risk factors, including age and blood pressure. Nevertheless, clinical practice guidelines rarely recommend the routine use of arterial stiffness in daily care. To facilitate the routine use of arterial stiffness measurements, the corresponding translational gaps in the clinical application should be analyzed and addressed.
To justify the routine clinical use of any biomarkers, several criteria must be met. For the many methodologies to estimate arterial stiffness, their reliability and reproducibility in a standard clinical setting should be firstly demonstrated. Moreover, in a busy clinical environment, a less complicated measurement procedure with operator independence is more welcomed. Second, these techniques must carry the ability to add additional risk discrimination beyond the conventional risk prediction systems such as Framingham risk score or SCORE and should be cost effective. Not only the independent prognostic value but also the significant reclassification ability should be shown. Lastly, clear indication of the implementation of arterial stiffness techniques should be provided including but not limited to being used for risk stratification, treatment monitoring, or as a therapeutic target.
Previous studies pertaining to arterial stiffness have been endeavored to address most but not all the above requirements. The independent value of arterial stiffness in predicting cardiovascular events have been presented. Moreover, its ability to predict incident hypertension and target organ damage, including brain, heart, and kidney have also been confirmed. In an individual patient data meta-analysis of cf-PWV for subjects at intermediate risk, adding cf-PWV into standard risk factors rendered a net reclassification of 15% and 27% for coronary heart disease events and CVD death, respectively. Such analysis provide justification to apply arterial stiffness measurements in routine clinical practice. They can make risk prediction more accurate by re-classifying subjects with intermediate cardiovascular risk into a higher risk level, in which treatment is indicated or into a lower risk level, in which further therapy could be safely avoided. In subjects with intermediate risk such as whitecoat hypertension, isolated diastolic hypertension, or borderline hypertension, the uncertainty in risk prediction may be further reduced by measuring arterial stiffness.
Of the techniques for estimating arterial stiffness, advantages and disadvantages of each technique are observed. Although cf-PWV has the strongest evidence base supporting clinical value, the operator independence limits its widely use in routine practice. Cuff-based devices require less training, but may be less accurate. Further research is required to address this important unmet need. Besides, recommendation of the routine use of arterial stiffness techniques could be further supported by conducting randomized controlled trials adopting arterial stiffness as a treatment target, a treatment monitoring instrument, or as a tool incorporated in the intervention strategies such as risk stratification for subjects with intermediate risk profiles. To obtain health insurance reimbursement, cost-effectiveness analysis accompanied with the prospective studies for arterial stiffness is also warranted to support its routine clinical implement.
In summary, the distinctive clinical value of arterial stiffness techniques relies on the ability of a single assessment to provide important information regarding blood pressure progression and susceptibility to end organ damage. The most useful scenario seems to be the more accurate risk classification for subjects at intermediate CVD risk, in which condition the need for treatment is uncertain, such as patients with masked or white coat hypertension. Therefore, arterial stiffness can be seen as complimentary to current blood pressure, and both should be considered when risk prediction is required for making timely and relevant treatment decisions. The role of arterial stiffness as a treatment target, treatment monitoring strategy in response to therapy, or a tool in the intervention strategy should be further uncovered in prospective studies or randomized controlled trials.