Nebivolol improves coronary flow reserve in patients with idiopathic dilated cardiomyopathy

Background: Impaired coronary flow reserve (CFR) is a significant predictor of poor prognosis in patients with idiopathic dilated cardiomyopathy (IDC). Nebivolol reduces mortality and morbidity in patients with heart failure and left ventricular dysfunction, including cases caused by IDC. Objective: To assess the effects of nebivolol on CFR in patients with IDC. Methods: CFR was measured in 21 clinically stable patients with IDC (mean (SD) ejection fraction 35.7 (6.2)) at baseline and after 1 month of treatment with nebivolol once daily. A control group of apparently healthy subjects who were matched for age and sex was used for comparison. Resting and hyperaemic coronary flows were measured using transthoracic second-harmonic Doppler echocardiography. None of the subjects had any systemic disease. Results: After 1 month of treatment, heart rate was reduced significantly (p < 0.001). The blood pressure was decreased significantly (p < 0.001). The left ventricular end-diastolic diameter and stroke volume were not changed significantly, but end-systolic diameter was decreased significantly (p < 0.05). Resting rate-pressure product was lower after treatment with nebivolol, but dipyridamole-induced change was not influenced by the treatment. Nebivolol treatment reduced significantly coronary velocities at rest (p < 0.02) and also caused a significant increase in coronary velocities after dipyridamole (p < 0.02), leading to a greater CFR (2.02 (0.35) vs 2.61 (0.43), p < 0.001). Nebivolol induced an absolute increase of 6% in the CFR in 17 of 21 patients (80.9%). Conclusions: In patients with IDC, 1 month of treatment with nebivolol induces a marked increase in CFR.