Comparison of the effects of doxazosin and atenolol on target organ damage in adults with type 2 diabetes mellitus and hypertension in the CARDHIAC study: a 9-month, prospective, randomized, open-label, blinded-evaluation trial

Abstract

Objective: The CARDHIAC (CARduran en pacientes Diabéticos con HIpertensi'on Arterial no Controlada) trial examined the effects of doxazosin gastrointestinal therapeutic system (GITS) and atenolol on 3 separate measures of target-organ damage--left ventricular mass index (LVMI), carotid intima media thickness (IMT), and urinary albumin excretion (UAE)--in patients with type 2 diabetes mellitus and hypertension.

Method: This trial had a prospective, open-label, blinded-evaluation design and a duration of 9 months. Patients whose blood pressure (BP) was uncontrolled (systolic BP > or = 130 mm Hg and/or diastolic BP > or = 80 mm Hg) despite at least 1 month of treatment with a renin-angiotensin blocker and diuretic were randomly allocated to receive doxazosin GITS 4 mg or atenolol 50 mg once daily in addition to their existing treatment. Seated BP was measured at study visits at 1, 3, 6 and 9 months; if the BP goal was not achieved at any visit, the dose of doxazosin or atenolol was titrated upward to 8 or 100 mg, respectively. Treatment compliance (pill count) and adverse reactions were monitored at each visit. Each patient underwent echocardiography and Doppler ultrasonography at baseline and at the end of the study for evaluation of the change in LVMI. The change in carotid IMT was evaluated by carotid ultrasound examination at the same time points. UAE also was measured at baseline and the end of the study.

Results: Sixty patients (100% white; 51% female; mean [SD] age, 63.4 [7.5] years; body mass index, 28.2 [3.4] kg/m(2)) were randomized to receive doxazosin GITS (n=32) or atenolol (n=28). At baseline, mean BP was 150.2 (10.6)/90.1 (7.3) mm Hg in the doxazosin group and 153.1 (13.8)/92.3 (6.1) mm Hg in the atenolol group (P=NS). At the end of the study, BP had decreased by 10.1 (3.2)/5.2 (1.3) mm Hg in the doxazosin group and 12.2 (4.2)/6.3 (2.1) mm Hg in the atenolol group (both, P<0.001 vs baseline; P=NS between groups). Heart rate at the end of the study was 78(6) beats/min in the doxazosin group (P=NS vs baseline) and 66(7) beats/min in the atenolol group (P<0.01 vs baseline and between groups). LVMI decreased by 10.8 in the doxazosin group (P=0.001 vs baseline) and 4.2% in the atenolol group (P=NS vs baseline; P=0.03 between groups). The changes in carotid IMT and UAE were not statistically significant between groups.

Conclusions: In this study in hypertensive patients with type 2 diabetes, LVMI was significantly decreased in doxazosin-treated patients relative to baseline and compared with atenolol-treated patients. The differences in carotid IMT and UAE were not statistically significant between groups.