Effects of Selective α1- and α2-Adrenergic Blockade on Coronary Flow Reserve After Coronary Stenting

Background— Coronary flow reserve (CFR) is not normalized shortly after coronary stenting. We hypothesized that α-adrenergic coronary vasoconstriction acts to limit CFR. Methods and Results— We assessed flow velocity by Doppler wires and cross-sectional area by angiography in 46 patients undergoing coronary culprit lesion stenting (81±4% stenosis). Hyperemia was induced by adenosine (24 μg IC or 140 μg/kg per minute IV) before and after stenting. Finally, either the α1-antagonist urapidil (10 mg IC) or the α2-antagonist yohimbine (3 mg IC) was randomly combined with adenosine. In 8 subjects with angiographically normal coronary arteries, CFR was increased from 3.21±0.30 to 3.74±0.43 by yohimbine and to 4.58±0.65 by urapidil, respectively (P=0.0001). Patients were divided according to the cutoff of CFR ≥3.0 (n=18) or <2.5 (n=28). Revascularization per se did not change CFR. However, 15 minutes after stenting, CFR decreased to 2.05±0.55 from CFR 3.64±0.58, whereas in patients with CFR 2.39±0.51, it remained...