This trial aims to investigate of the role of the patient's own bone marrow stem cells in patients with severe, chronic ischaemic heart disease. The trial is being conducted by the Heart Institute São Paulo and the Ministry of Health Brazil at several centres and expects to enrol 200 patients. Participants will be randomly divided into two groups. The experimental group will receive an injection of stem cells from their own bone marrow directly into the heart at the time of the surgery. The control group will receive a placebo injection at the time of the surgery. Participants will be monitored for complications and changes in clinical condition, including left ventricular function and any changes in functional angina. Both the participants and the clinicians will be not be aware of the treatment the patient has received.