Differential effects of nifedipine and co-amilozide on the progression of early carotid wall changes

Abstract

Background - Common carotid artery intima-media thickness (IMT) progression was compared between 4 years of treatment with nifedipine and diuretic. Methods and Results - This study, ancillary to the International Nifedipine GITS Study: Intervention as a Goal in Hypertension Treatment (INSIGHT), involved nifedipine 30 mg or co-amilozide (hydrochlorothiazide 25 mg and amiloride 2.5 mg) with optional subsequent titration. Among 439 randomized hypertensive-patients, 324 had ≥1 year of follow-up (intent-to-treat group), and 242 completed follow-up (until-end-of-study group). Ultrasonography was performed at baseline, 4 months later, and then every year. Central computerized reading provided far-wall IMT, diameter, and cross-sectional area IMT (CSA-IMT). The primary outcome was IMT progression rate (slope of IMT-time regression). Secondary outcomes were changes from baseline (Δ) in IMT, diameter, and CSA-IMT. In the until-end-of-study population, between-treatment differences existed in IMT progression rate (P=0.002), Δ IMT (P=0.001), and Δ CSA-IMT (P=0.006), because IMT progressed on co-amilozide but not on nifedipine. In the intent-to-treat population, treatment differences existed in Δ IMT (P=0.004) and Δ CSA-IMT (P=0.04) but not in IMT progression rate (P=0.09). Patients with ≥2, 3, or 4 years of follow-up showed treatment differences in IMT progression rate (P=0.04, 0.004, 0.007, respectively), Δ IMT (P=0.005, 0.001, 0.005), and Δ CSA-IMT (P=0.025, 0.013, 0.015). Diameter decreased more on co-amilozide than on nifedipine in the intent-to-treat population (P<0.05), whereas blood pressure decreased similarly on both treatments. Conclusions - A difference in early carotid wall changes is shown between 2 equally effective antihypertensive treatments.