Objective: We used antihypertensive drugs as pharmacologic tools to clarify the physiologic meaning of the ambulatory arterial stiffness index (AASI) in comparison to pulse pressures (PP), the arterio-ventricular coupling index (AVCI), and aortic pulse wave velocity (aPWV).

Methods: After a 4-week placebo period, 94 and 107 patients with uncomplicated hypertension were randomly assigned to treatment for one year with atenolol 50 mg/d (AT) or perindopril/indapamide 2/0.6 mg/d (PER/IND). From the individual readings in each patient’s 24‑hour ambulatory BP recording, we determined 24‑hour systolic and diastolic BP. We computed PP as the difference between 24‑hour systolic and diastolic BP, AASI as unity minus the regression slope of diastolic on systolic BP, and AVCI as (T/τ)/(1+2T/3τ)), where T is the heart period in seconds and τ is the decay time of aortic BP during diastole.

Results: Compared to PER/IND, in patients on AT, systolic BP and PP decreased less and AVCI lengthened more (P≤0.009), whereas the changes in AASI and aPWV did not differ between the two treatment groups (P≥0.25). In patients with the metabolic syndrome (NCEP-ATPIII criteria), AT and PER/IND lowered systolic BP similarly, but AT lowered diastolic BP more than PER/IND. Conversely, in patients without the metabolic syndrome, PER/IND lowered systolic BP more than AT, but diastolic BP to a similar extent.

Conclusions: On antihypertensive drugs with a different hemodynamic profile, AASI and aPWV behaved similarly. The metabolic syndrome seems to modulate the impact of antihypertensive drugs on systolic BP and PP.