- Brain natriuretic peptide (BNP, NT-pro BNP) after a 6-months period of treatment with nebivolol versus metoprolol. An improvement of more than 20% of the myocardial resting velocities of systolic functional reserve is considered to be clinically relevant. The working hypothesis is that the improvement of subclinical left ventricular dysfunction after 6 months of treatment is going to be greater in patients who receive nebivolol than in those who receive metoprolol.