Efficacy of pre-emptive milrinone in off-pump coronary artery bypass surgery: comparison between patients with a low and normal pre-graft cardiac index

OBJECTIVE: The effect of pre-emptive milrinone without bolus during off-pump coronary artery bypass surgery (OPCAB) was evaluated in two groups of patients with low and normal pre-graft cardiac index. METHODS: Eighty-two patients were divided into two groups based on their pre-graft cardiac index. Each group was randomly subdivided into two groups to receive either milrinone or normal saline. After the internal mammary artery was harvested, the infusion of milrinone, or normal saline was started and maintained until the end of the anastomosis. The haemodynamic variables were measured: just before the start of milrinone or normal saline after pericardiotomy (baseline value); 10 min after the tissue stabilizer had been applied for the anastomosis of left anterior descending artery, left circumflex artery and right coronary artery; and after the sternal closure. RESULTS: Milrinone reduced the extent of the decrease in cardiac index and stroke volume as well as the extent of the increase in systemic and pulmonary vascular resistance. The extent of the decrease in cardiac index and mixed venous oxygen saturation were greater in normal pre-graft cardiac index group than in low pre-graft cardiac index group regardless of milrinone infusion during anastomoses. The effect of milrinone on haemodynamics showed no significant difference between low and normal pre-graft cardiac index groups. CONCLUSIONS: Pre-emptive milrinone infusion without bolus effectively improved cardiac performance during OPCAB and was especially useful for patients with low pre-graft cardiac index to prevent the decrease in cardiac index and stroke volume index below the critical level.