Silent myocardial ischemia is known to occur in the general medical intensive care unit
population immediately following tracheal extubation. We believe these patients are at risk
for primary cardiac events in the 4 hours immediately following extubation. Metoprolol is a
selective beta-1 antagonist, with little to no beta-2 activity at low and moderate doses. The
cardioprotective effects of beta blockade have been well documented in randomized controlled
trials. In patients undergoing extubation, prophylactic use of intravenous metoprolol may
reduce post-extubation ischemia events as well as precursors of cardiogenic pulmonary edema
(atrial and ventricular wall tension). Our primary hypothesis is that prophylactic metoprolol
(titrated to reduce resting heart rate by at least 10%) prior to tracheal extubation will
reduce the rate of ischemia as judged by ST segment analysis.