The nine patients in the control group received no treatment.
Patients were monitored on treadmill tests and had blood tests to see if the stem cells caused inflammation.
Researchers measured "reversible defects" (live heart muscle tissue that's not getting enough blood flow) and "fixed defects" (dead tissue that has become scar tissue) at baseline, two and six months.
In the treatment group, the total reversible defect made up about 15 percent of the tissue at baseline. That was reduced to an average 4.5 percent at two months and 8.8 percent at six months. Among controls, reversible defects increased from an average 10 percent at baseline to 32 percent at two and six months.
"There wasn't significant change in the amount of scar tissue between the two groups. The scar didn't change or get worse in the treated group, and the area that lacked blood flow got better in the treatment group," Perin said.
Oxygen consumption (VO2 max) and the body's ability to exercise are directly related to how well the heart can pump. "Patients who have a VO2 max of less than 14 are generally near death. A lot of the patients in this trial were close to that number at the beginning of the study," Perin said.
Patients in the treatment group started with an average VO2 max of 18ml/Kg/min (milliliters per kilogram per minute) and the control group had 17.7ml/Kg/min. The treatment group went up to 23ml/Kg/min in the first two months while the controls were at an average 18ml/Kg/min. At six months, the treatment group averaged 24ml/Kg/min, while the control group was at 17ml/Kg/min.
Metabolic equivalents (METs), which also relate to the heart's function on a treadmill, rose for the treatment group from an average 5 at baseline to 7 at six months. The control group, which started at an average MET of 5, finished the study at 4.9.