Effect of Quinapril and Triamterene/Hydrochlorothiazide on Cardiac and Vascular End-Organ Damage in Isolated Systolic Hypertension

We compared, in a prospective double-blind randomized study, the effect of the angiotensin-converting enzyme inhibitor quinapril (QUI) with that of triamterene/hydrochlorothiazide (THCT) treatment on cardiovascular end-organ damage in subjects with untreated isolated systolic hypertension (ISH). End-organ damage measurements, performed initially and after 6 and 26 weeks of treatment, included echocardiographic determination of left ventricular mass index (LVMI) and of diastolic function and measurement of aortic distensibility and peripheral vascular resistance. Blood pressure was significantly reduced in the 44 subjects (21 QUI, 23 THCT) completing the study. Both LVMI and aortic distensibility had changed at 6 weeks, with comparable improvements in both groups. LV diastolic function showed overall no significant changes, although patterns of early filling did differ between the two drug groups. Peripheral vascular resistance appeared to increase between 6 and 26 weeks in THCT subjects only, along with a decreased aortic distensibility. Blood pressure and LV mass were rapidly and markedly reduced in both treatment groups of ISH subjects, paralleled by an improvement of aortic distensibility. In interpreting these results, the pathophysiologic alterations in ISH need to be taken into account, because these differ strongly from those in diastolic hypertension. Results of LV diastolic function and peripheral vascular resistance were less clear but appear to show less favorable changes in the THCT subjects treatment group.