Background: Microvascular and endothelial dysfunction have been implicated for coronary slow flow (CSF). Nebivolol, besides its beta-receptor blocking activity, causes an endothelium-dependent vasodilatation through increased nitric oxide release.
Methods: This study included 27 patients with CSF and 27 subjects with normal coronary arteries. Segmental functions of the left ventricle (LV) were assessed using myocardial tissue Doppler velocities before and 3 months after treatment with nebivolol 5 mg/day.
Results: Compared with the control group, mitral deceleration time (DT) was significantly longer, and E/A ratio, systolic velocity of lateral mitral annulus (S(m)) and regional myocardial peak systolic and early diastolic velocities (V( s), V(d)) were significantly lower in patients with CSF. The reason for coronary angiography was typical angina in 21 (77.8%) and positive treadmill test in six (22.2%) CSF patients. There were significant correlations between presence of CSF in left anterior descending artery (LAD) with S( m) (r =-0.404, p =0.002) and V(s) in anterior (r =-0.531, p < 0.001 ) and lateral (r =-0.495, p < 0.001 ) segments and between presence of CSF in RCA and V(s) in posterior segments (r =-0.501, p < 0.001). Treatment with nebivolol significantly decreased blood pressures (128.5+/-12.5/82.5+/-8.8 to 119.8+/- 12.6/76.4+/- 7.4 mmHg, p < 0.001), DT (252.3+/-53.6 to 222.0+/-41.0 ms, p < 0.001 ) and IVRT (115.7+/-19.9 to 103.3+/-17.0 ms, p <0.001), and increased exercise capacity (8.7+/-1.3 to 10.4+/-0.9 METs, p < 0.001), E/A ratio (0.87+/-0.26 to 1.08+/-0.23, p <0.001) and myocardial velocities (p < 0.001). All the patients were free of angina after treatment. Patients with CSF had impaired diastolic and regional LV functions.
Conclusions: Nebivolol may therefore be useful in improving angina, exercise capacity and LV functions in patients with CSF.