The PRECISE cardiac stem cell clinical trial was designed by a team of world renowned cardiac researchers, including Dr. Emerson Perin from Texas Heart Institute and Dr. Francisco Fernandez-Aviles. It examined the safety and feasibility of adipose-derived stem and regenerative cells (ADRCs) in the treatment of those with severe coronary artery disease.
Results of the PRECISE Cardiac Stem Cell Clinical Trial
The 18 month study showed that treating patients with chronic coronary artery disease with ADRCs:
- Is safe and feasible
- Showed significant benefit in heart function
Improvement in Heart Function
Better heart function leads to improved quality and length of life. The PRECISE cardiac clinical study demonstrated improvement in key measures of heart function, leading to a reduction in symptoms. The two key measures of heart function are:
- MVO2, or maximum volume of oxygen consumed—the maximum amount of oxygen that a person can use. This is the best predictor of cardiac-related mortality.
- MET score, or metabolic equivalent of task score—a way to measure a patient’s physical strength and a strong predictor of adverse cardiac-related events.
What Does This Mean to Patients with Chronic Coronary Artery Disease?
Patients who received stem cell therapy in the cardiac clinical trial showed
- Sustained improvement in MVO2
- Improvement in MET score
- Reduction in infarct size (the amount of the diseased heart tissue)
Maximum Amount of Oxygen Consumed—MVO2
In the PRECISE trial, one of the most important findings was the improvement in MVO2. The MVO2 levels define a measure of how efficiently the body’s tissue utilizes oxygen 18 months after treatment:
- Those patients who received the stem cell therapy improved their MVO2 from approximately 16 to over 17, on average.
- Those patients who did not receive the stem cell therapy (control group) suffered a steep decline from approximately 19 to 15.
A patient with MVO2 of 14 or less has a 53% risk of dying within 12 months. The data suggests an MVO2 of 16 or greater suggests a lower risk of cardiac-related death.
The survival rate at 28 months of average follow up time was predicted by the trend in oxygen consumption.
- Stem cell treated patients had better survival: 1 out of 21 had a cardiac-related death in the trial.
- The placebo group mortality rate, however, was 2 out of 6 placebo patients died of cardiac causes in the trial.
Metabolic Equivalent of Task Score—MET Score
A MET (Metabolic Equivalent of Task) score describes the amount of energy required to carry out a task. A MET score is a strong predictor of cardiac-related adverse events as well as mortality.
The PRECISE study population had a MET score of approximately 5, which put them at high risk in the near term. Eighteen months after treatment:
- Patients who received the stem cell therapy improved their MET score from approximately 4.8 to 5.0 in 6 months, and sustained that through the 18 month period.
- Patients who did not receive the stem cell therapy (control group) suffered a decline in function. On average, their MET score fell from approximately 5.3 to 4.4 in the 6 month period, and continued to trend downward at 18 months.
Infarct is the dead tissue tissue that results from the interruption of blood flow to the heart. Infarct size is also a strong predictor of patient mortality and adverse cardiac-related events.
The PRECISE trial also demonstrated a statistically significant improvement in infarct size in the heart. Infarct size is also a strong predictor of patient mortality and adverse cardiac-related events.
Rigorous Research—How It Was Done
The PRECISE study recruited patients with chronic myocardial ischemia, a severe form of coronary artery disease. In order to function properly, the heart needs an adequate blood supply. In those patients with chronic myocardial ischemia, blood flow to the heart has been compromised for years. This weakens the heart muscle and leads to heart failure. In the PRECISE study:
- Adipose tissue (fat) was obtained by liposuction from the patients’ own abdomens.
- ADRCs (adipose derived stem and regenerative cells) were then extracted from the fat tissue.
- Access to the heart was gained via an artery in the groin and;
- The cells were delivered via catheter into areas of damaged heart muscle.
One third of the patients did not receive an injection of cells but rather a placebo, an inactive substance with no effect on the heart. This group of patients is the control group. They allow researchers to show, by comparison, if the injection of stem cells in the cardiac clinical trial is effective.
A Primer on How Heart Function is Measured
Aerobic Capacity and MVO2
Aerobic capacity can be measured using the MVO2 test. MVO2 is the greatest amount of oxygen that a person can use in one minute. In order to use oxygen, it must be inhaled, transported around the body and used in metabolism. Thus, a high MVO2 number reflects a healthy heart, strong lungs and open blood vessels. It is measured by looking at how well a person can tolerate exercise on a treadmill. This exercise is carried out while breathing into a respirometer mouthpiece. The treadmill gets faster until the subject can no longer carry on. The MVO2 is calculated by the respirometer.
Physical Strength and MET Score
When a person sits quietly, they use about 1 MET of energy. However, a person weighing 210 lbs will burn more calories than an individual weighing 110 lbs. The formula for calculating MET Score allows for differences in size so people can be fairly compared. METS are also measured by testing a person on a treadmill. Running will generally produce an energy expenditure of 7 to 10 METS. If someone can do ten METS on a treadmill, they are in excellent condition. Patients that can do only five METS or less typically have a high incidence of adverse cardiac-related events in the near future.
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