Comparison of the efficacy between hydrochlorothiazide and chlorthalidone on central aortic pressure when added on to candesartan in treatment-naïve patients of hypertension.

Thiazide-type diuretics are the most commonly used blood pressure (BP)-lowering drug for patients with uncomplicated hypertension. However, it has remained unclear whether hydrochlorothiazide (HCTZ) or chlorthalidone (CTD) shows better improvement in central aortic pressure. We conducted an open-label, randomized, prospective cross-over study with an 8-week active treatment (HCTZ of 25 mg with candesartan of 8 mg or CTD of 12.5 mg with candesartan of 8 mg) with a 4-week washout period (only candesartan during this period). Twenty-eight treatment-naïve patients of hypertension were enrolled (mean age: 50±9 years, male: 44.4%). Central aortic pressure, pulse wave velocity (PWV), augmentation index (AIx) and other BP-derived parameters were measured. After 8 weeks of active treatment, there was no significant difference in changes of central aortic pressure between HCTZ and CTD treatments (Δ=-14±8 vs. -16±7 mm Hg, P=0.645). However, CTD treatment showed a significant reduction in PWV compared with baseline (1321±194 vs. 1439±190 cm s(-1), P=0.007) and HCTZ treatment (Δ=-118±82 vs. Δ=5±72 cm s(-1), P=0.033), whereas HCTZ treatment showed a marginal, but not a significant reduction in AIx compared with baseline. In conclusion, CTD of 12.5 mg is as potent as HCTZ of 25 mg, when combined with candesartan of 8 mg, in lowering central aortic pressure. In addition, CTD treatment resulted in a significant reduction of PWV.