P3.20 CLINICAL SIGNIFICANCE OF AMBULATORY ARTERIAL STIFFNESS INDEX (AASI) IN YOUNG STAGE 1 HYPERTENSIVE’ S

The aim of the study was to examine the relationship between AASI and age in a cohort of stage I hypertensives < 50 years of age and to investigate its predictive capacity for future established hypertension. We studied 1157 subjects from the HARVEST study (mean follow-up 5.9 years). AASI and 24-h pulse pressure (PP) were calculated from 24-h ambulatory recordings. The predictive value of AASI for incident hypertension was evaluated with Cox regression analysis adjusting for age, sex, mean 24-h blood pressure (BP). Baseline office BP was 145.5±10.4/93.6±5.6 mmHg, 24-h PP was 49.6±11.2 mmHg, AASI was 0.56±0.2. AASI was correlated with 24-h PP (r = 0.41, p<0.0001), and showed a U-shaped correlation with age. In our population age was inversely correlated with 24-h PP (r = -0.32, p<0.0001). The highest sex-adjusted AASI values were found in the two bottom and the top age deciles (mean±SEM, 0.62±0.02, 0.61 ±0.02, and 0.60±0.02, respectively). During follow-up 55.7% of the subjects developed established hypertension needing pharmacological treatment. In a multivariate Cox analysis, AASI showed a negative predictive value for the development of future hypertension (p<0.001). Participants in the middle AASI tertile (H.R. and 95%CI: 0.81, 0.67–0.97, p = 0.03) and top tertile (0.71, 0.57–0.87, p = 0.001) had a lower risk of developing hypertension compared to subjects in the bottom tertile. AASI shows a U-shaped relationship with age in a population of young-to-middle-age hypertensives and it may be even a predictor of better outcome. So, the clinical significance of AASI in hypertension appears to be heavily dependent on age.