The majority of postoperative myocardial ischemia in high-risk patients tends to develop on the day of or the day after surgery. The vast majority of perioperative myocardial infarctions are preceded by episodes of ST-segment depression. B-blocker therapy has most extensively studied with regard to its protective action against the occurrence of perioperative myocardial ischemia by decreasing myocardial oxygen demand secondary to lower heart rates and a decrease in myocardial contractility, antiarrhythmic effects, coronary plaque stabilizing effects, anti-inflammatory effects, a shift in energy metabolism, and anti-renin-angiotensin effect.