Decreased risk of ventricular arrhythmias with treatment of nebivolol in patients with coronary slow flow.

Background: Coronary slow-flow (CSF) is an angiographic phenomenon characterised by delayed opacification of vessels in the absence of any evidence of obstructive epicardial coronary disease. QT interval dispersion (QTD) reflects regional variations in ventricular repolarisation and cardiac electrical instability and has been reported to be longer in patients with CSF. Aim: To examine QT duration and dispersion in patients with CSF and the effects of nebivolol on these parameters. Methods: The study population included 67 patients with angiographically proven normal coronary arteries and CSF, and 38 patients with angiographically proven normal coronary arteries without associated CSF. The patients were evaluated with 12-lead electrocardiography, and echocardiography before and three months after treatment with nebivolol. Results: Compared to the control group QTcmax and QTcD were significantly longer in patients with CSF (p = 0.036, p = 0.019, respectively). QTcD significantly correlated with the presence of CSF (r = 0.496, p < 0.001). QTcmax (p = 0.027), QTcD (p = 0.002), blood pressure (p = 0.001), and heart rate (p < 0.001) values significantly decreased after treatment with nebivolol. Conclusions: Coronary slow flow is associated with increased QTD. Nebivolol reduced increased QTD in patients with CSF after three months.