OBJECTIVES: Perioperative low cardiac output syndrome occurs in 3-14% of patients undergoing isolated coronary artery bypass grafting (CABG), leading to significant increase in major morbidity and mortality. Considering the unique pharmacological and pharmacokinetic properties of levosimendan, we conducted a prospective, double-blind, randomized pilot study to evaluate the effectiveness of prophylactic levosimendan in patients with impaired left ventricular function undergoing CABG.METHODS: Thirty-two patients undergoing CABG with low left ventricular ejection fraction (LVEF ≤ 40%) were randomized to receive either a continuous infusion of levosimendan at a dose of 0.1 μg/kg/min for 24 h without a loading dose or a placebo. The primary outcome of the study was the change in the LVEF assessed with transthoracic echocardiography on the seventh postoperative day. Secondary outcomes included the physiological and clinical effects of levosimendan.RESULTS: All patients tolerated preoperative infusion of levosimendan well. The LVEF improved in both groups; this increase was statistically significant in the levosimendan group (from 35.8 ± 5% preoperatively to 42.8 ± 7.8%, P = 0.001) compared with the control group (from 37.5 ± 3.4% preoperatively to 41.2 ± 8.3%, P = 0.1). The cardiac index, SvO, pulmonary capillary wedge pressure and right ventricular stroke work index showed a similar trend, which was optimized in patients treated with levosimendan. Moreover, an increase in extravascular lung water was noticed in this group during the first 24 h after surgery.CONCLUSIONS: This pilot study shows that prophylactic levosimendan infusion is safe and effective in increasing the LVEF postoperatively in patients with impaired cardiac function undergoing coronary surgery. This finding may be translated to 'optimizing' patients' status before surgery.