Treatment-induced changes in ambulatory arterial stiffness index: one-year prospective study and meta-analysis of evidence

The ambulatory arterial stiffness index (AASI) has been introduced as an index of arterial function, predicting cardiovascular events. However, treatment-induced changes in AASI are rather equivocal. This study aims to: (i) present the results of treatment-induced changes in AASI in untreated subjects with elevated blood pressure (BP), subjected to antihypertensive treatment for 1 year and (ii) perform a meta-analysis of studies reporting on treatment-induced change in AASI. A total of 104 subjects (mean age 51.4 +/- 10.3 years, 62% males, mean follow-up: 13.6 +/- 2.4 months) were analyzed. Despite significant reductions in 24-h ambulatory systolic/diastolic BP, pulse pressure and pulse wave velocity (mean change: -15.9 +/- 12/-10.4 +/- 7.6 mm Hg, -5.4 +/- 6.8 mm Hg, -0.7 +/- 1.9 ms(-1), respectively, all P<0.05), there was no significant change (Follow up-Baseline) in AASI values (mean change: 0.01 +/- 0.17, P=not significant). The treatment-induced change in AASI was correlated with baseline AASI (r=-0.61), baseline 24-h pulse pressure (-0.26), treatment-induced change in 24-h pulse pressure (0.26) and in systolic/diastolic nocturnal dipping (-0.25/-0.40, respectively). Meta-analysis of eight trials (n=990) revealed a marginal decrease in AASI with antihypertensive treatment (pooled change: -0.018 (95% confidence interval (CI): -0.033, -0.003)). When the analysis was restricted to data with renin-angiotensin system blockers (n=755, 76% of total), the results did not significantly change (pooled change -0.028 (95% CI -0.048, -0.007)). In conclusion, although AASI is an independent predictor of cardiovascular events, its response to antihypertensive treatment is only marginal and clinically uncertain, which may render its use as a therapeutic target in clinical practice questionable.