Impact of α- Versus β-Blockers on Hypertensive Target Organ Damage: Results of a Double-Blind, Randomized, Controlled Clinical Trial

In hypertensive disease, the extent of target organ damage determines the prognosis. We conducted a 6-month, double-blind randomized study to compare the effects of an α1-adrenoreceptor blocker (bunazosin) with those of a β1-adrenoreceptor blocker (metoprolol) on early hypertensive target organ damage at a similar level of blood pressure reduction. The study consisted of 43 patients (29 men and 14 women) of varying ages (mean age 52 ± 9 years) with essential hypertension World Health Organization stage I–II. Both the α- and the β-blocker lowered blood pressure to a similar extent measured by 24-h blood pressure monitoring. The left ventricular mass was comparably reduced in both cohorts (α-blocker 284 ± 80 v 259 ± 67 g, P< .05, β-blocker 282 ± 74 v 254 ± 70 g, P< .05). Treatment with the α-blocker led to reduced total peripheral resistance (22.9 ± 8.0 v 19.9 ± 5.3 U, P< .05), whereas therapy with the β-blocker resulted in an elevated total peripheral resistance (25.5 ± 8.4 v 28.5 ± 9.3 U, P< .10; P< .05 for the difference in both groups). Renal plasma flow remained constant in the α-blocker treated group but decreased in the β-blocker treated group (508 ± 141 v 477 ± 134 mL/min/1.73 m2, P< .05). Glomerular filtration rate as measured by inulin clearance tended to increase after treatment with the α-blocker (112 ± 20 v 115 ± 18 mL/min/1.73 m2, P< .10) in accordance with a decrease of serum creatinine (1.00 ± 0.14 v 0.93 ± 0.12 mg/dL, P< .001). Plasma cholesterol and LDL cholesterol was lowered after treatment with the α-blocker (238 ± 48 v 312 ± 37 mg/dL; P< .001, and 153 ± 32 v 130 ± 25 mg/dL; P< .05) while remaining unchanged in group treated with the β-blocker. Left ventricular hypertrophy was similarily reduced with α- and with β-blockade at a comparable reduction of 24-h blood pressure. α-Blockers effected a more favorable renal and systemic hemodynamic profile than β-blockers, but only long-term prospective studies will answer the question whether these hemodynamic effects result into a better cardiovascular prognosis.