The radial augmentation index: Determinants and association with left ventricular hypertrophy

It has been proposed that wave reflection depends on entire arterial properties and augments central blood pressure (BP) during late systole, thus increasing cardiac afterload. To clarify the clinical significance of the radial augmentation index (AIr), we examined the determinants in a general population (study 1), and the relationship between AIr and left ventricular hypertrophy (LVH) in hypertensive patients (study 2). In study 1, we surveyed 803 individuals aged 63+11 years from the general population of Ohasama, Japan. The radial pulse wave was recorded using applanation tonometry. Brachial-ankle pulse wave velocity (PWVba) was also measured to examine its correlation with AIr. In study 2, AIr and echocardiographic parmeters were determined in 77 untreated hypertensive patients aged 56+10 years. LVH was defined based on the left ventricular mass index (LVMI). Patient characteristics were compared between the groups with (+) and without (−) LVH. We also compared the ability of AIr and carotid-femoral pulse wave velocity (PWVcf) to detect LVH by using ROC analysis. Multivariate linear regression analysis showed that AIr was correlated independently and positively with age and brachial BP, and negatively with heart rate (HR) and body height (P<0.001). Gender and smoking were also associated with AIr. There was only a weak correlation between AIr and PWVba (r=0.17). LVMI was significantly correlated with AIr and late systolic peak pressure, but not with brachial mean arterial pressure (MAP). AIr tended to be correlated negatively with the E/A ratio of the diastolic transmitral flow. The LVH (+) group had a significant higher AIr than the LVH (−) group (P=0.003), even after adjustment for age, gender, MAP and HR (P=0.01). On logistic regression analysis, the adjusted relative risk of LVH was 1.99 for each 10% AI increase. The area under the curve for AIr was greater than for PWVcf. These results indicate that AIr is clinically useful for assessing pathological changes in arterial wall properties induced by aging or smoking, although it is dependent on certain physiological factors. Enhanced wave reflection, as shown by an elevated AIr, is closely related to LVH in untreated hypertension.