Anastrozole in Pulmonary Arterial Hypertension. A Randomized, Double-Blind, Placebo-controlled Trial

Rationale: The aromatase inhibitor anastrozole blocks the conversion of androgens to estrogen and blunts pulmonary hypertension in animals, but its efficacy in treating patients with pulmonary arterial hypertension (PAH) is unknown.Objectives: We aimed to determine the safety and efficacy of anastrozole in PAH.Methods: We performed a randomized, double-blind, placebo-controlled trial of anastrozole in patients with PAH who received background therapy at two centers.Measurements and Main Results: A total of 18 patients with PAH were randomized to anastrozole 1 mg or matching placebo in a 2:1 ratio. The two co–primary outcomes were percent change from baseline in 17β-estradiol levels (E2) and tricuspid annular plane systolic excursion (TAPSE) at 3 months. Anastrozole significantly reduced E2 levels compared with placebo (percent change: −40%; interquartile range [IQR], −61 to −26% vs. −4%; IQR, −14 to +4%; P = 0.003), but there was no difference in TAPSE. Anastrozole significantly increased the 6-minute-wal...