55-year-old man was admitted to the ICU with an acute myocardial
infarction. He was managed with immediate cardiac catheterization and
balloon angioplasty of a totally occluded right coronary artery,
leaving a 30% residual stenosis. The creatine kinase
level was 2,200 U/L (17% MB fraction) 6 h after the procedure. At this
time, frequent runs of tachycardia begin to occur (Fig 1).
The patient is not aware of these, and is free of chest discomfort.
Which of the following therapies is most appropriate?