Patients with heart failure experienced a marked improvement after being given an injection of their own stem cells, investigators reported today at the Annual Meeting of the Society for Thoracic Surgery in Tampa, Florida.

Dr. Amit N. Patel, from the University of Pittsburg, and his associates previously found that stem cells injected during bypass surgery improve heart function. The current study is the first in which a minimally invasive technique was used, the researchers note.

Before the procedure, the patients underwent various tests to identify regions in the heart that were not beating properly. Using a tiny tube to visualize the heart muscle, the researchers injected stem cells into the poorly functioning areas of the hearts of 15 patients. Fifteen other patients served as a comparison group, receiving injections that lacked stem cells.

The patients who got the stem cells experienced a much greater improvement in heart function than comparison subjects. Moreover, ultrasound testing showed that the hearts of stem cell-treated patients shrank from an abnormally large size to a more normal size than did those of comparison subjects.

Despite participating in the same rehab program after treatment, the stem cell group showed a greater improvement in their walking ability than did the comparison group.

As to why stem cell therapy helps with heart failure, Patel cited several possible reasons, including stimulating blood vessel formation and muscle growth.

For their next trial, the investigators will be doing the same type of experiment but with patients who have extreme heart failure and are awaiting a heart transplant, Patel said. In contrast to the current group, these patients will receive stem cell injections to the entire heart, which will give “a more definitive answer as to what is actually happening to these cells,” he added.