The effects of intravenous enoximone were investigated in patients with reduced left ventricular ejection fraction following coronary artery bypass graft surgery. Pulmonary capillary wedge pressure was maintained at its original level during therapy. Results showed an improvement in cardiac index of approximately 35% and a reduction of systemic vascular resistance of approximately 30% in 10 out of 16 patients. In an attempt to explain the failure of 6 patients to respond to enoximone therapy, preliminary studies revealed that a repeat dose of enoximone may elicit a response. It is further suggested that postsurgical trauma may change the behaviour of the heart in response to this agent, perhaps due to a reduction in high-energy phosphate levels.