Arterial Stiffness in Special Populations

We greatly appreciate the work by Dr Hidekatsu Yanai1 that looked for correlations between arterial stiffness parameters and metabolic risk factors.

Special subpopulations have different arterial elasticity compared with healthy individuals. Diabetes mellitus has a plethora of risk factors that attribute to arterial stiffness. Identifying which metabolic factors are the strongest players in the association of diabetes mellitus and arterial stiffness is pivotal in understanding those that mostly contribute to atherosclerosis. Age is a nonmodifiable risk factor that is strongly correlated with both augmentation index (AIx) and pulse wave velocity (PWV) in Japanese patients, as described in the study by Yanai.1 Blood pressure (BP) also correlates with both AIx and PWV. These correlations were also significant in patients with sickle cell disease but also in other special populations such as those with chronic kidney disease.2, 3 However, patients with sickle cell disease had lower BP than controls but comparable PWV and higher AIx. In this particular subpopulation, AIx and PWV did not determine BP levels. Multivariate analysis in our study showed that PWV was solely influenced by age, but AIx was determined by age, waist circumference, and the presence of sickle cell disease.2 It would be interesting to see whether such an analysis was conducted in the study by Yanai.1 In other populations such as patients with rheumatoid arthritis, a more severe inflammatory status impacted arterial stiffness (as measured by PWV, AIx, and AIX standardized to a heart rate of 75 beats per minute).4 Therefore, arterial stiffness should be assessed in the context of the special features of each individual disease as well as ethnic disparity.

PWV and AIx are two different indices of arterial stiffness. PWV is a simple measure of the time taken by the pressure wave to travel over a specific distance. AIx is traditionally obtained from pressure waveforms via arterial applanation tonometry.5 It is intuitive that these two measurements produce different relative measurements of arterial stiffness in the same patient. Because PWV is highly reproducible and has a strong correlation with cardiovascular events and all‐cause mortality, it is widely recognized as the golden standard for measuring arterial stiffness and integral to the diagnosis and treatment of hypertension. Accepted thresholds for defining arterial stiffness exist only for PWV (10 m/s), while several thresholds have been proposed for Aix, with none being endorsed by official guidelines.6 As PWV is better correlated with cardiovascular outcomes and predicts cardiovascular mortality beyond traditional risk factors, it has a special gravity in describing arterial stiffness. Therefore, it remains the best choice for defining correlations with risk factors. To what extent a second, lesser surrogate of arterial stiffness such as AIx is needed is not yet clear. Perhaps adopting just one measurement may simplify result reporting for arterial stiffness.

In conclusion, arterial stiffness is determined by different factors depending on disease and ethnic background. Identifying these risk factors in special populations is pivotal in targeting them and improving cardiovascular outcomes through a more individualized approach. PWV is the best measurement we have to use as an outcome measure of any intervention aimed to improve arterial stiffness.

Disclosures

The authors report no specific funding in relation to this research and no conflicts of interest to disclose.