We hypothesize that the beta-blocker metoprolol succinate will be well tolerated by patients with moderate to very severe COPD and will reduce the risk of acute exacerbations of the disease. 

We will test this hypothesis by pursuing the following Specific Aims through the conduct of a randomized, placebo-controlled trial:

Primary: To determine the effect of once daily metoprolol succinate compared with placebo on the time to first exacerbation in moderate to severe COPD patients who are prone to exacerbations and who do not have absolute indications for beta-blocker therapy.

Secondary: To estimate the effect of metoprolol succinate compared with placebo on the rate and severity of COPD exacerbations over 12 months, incidence and severity of metoprolol-related side effects, lung function, dyspnea, exercise tolerance, quality of life, hospitalization rates, the rate of combined cardiovascular events (myocardial infarction, percutaneous coronary intervention, sudden death, stroke), and all-cause mortality.