The following factors had a significant influence on the use of positive inotropic drugs: age ≥ 65 years, female gender, congestive heart failure New York Heart Association class (NYHA) ≥ II, preoperative ejection fractions < 50%, pulmonary arterial systolic pressure (PAPs) > 40 mmHg, myocardial infarction recently, renal failure, chronic obstructive pulmonary disease (COPD), preoperative use of digitalis and ß-adrenergic blockers, type of surgical procedure, duration of surgery, cardiopulmonary bypass time, and aortic cross-clamping time > 90 minutes.