THI Cardiologists Study Growth Factor for Developing Blood Vessels

Cardiologists at the Texas Heart Institute at St. Luke's Episcopal Hospital are studying a revolutionary method to treat patients with clogged coronary arteries by using a new gene therapy to grow blood vessels to circumvent blocked arteries.

VEGF (vascular endothelial growth factor) is a growth factor the body uses to stimulate the growth of vessels. At the Texas Heart Institute, the procedure is being performed in a randomized study for patients who have been diagnosed with atherosclerotic coronary artery disease that is causing angina and cannot be treated by conventional methods.

"There is a growing body of evidence that one may be able to stimulate new blood vessel growth in the heart with this type of gene therapy," says Dr. James T. Willerson, medical director at the Texas Heart Institute and co-principal investigator of the trial. "We are very pleased to be involved in this clinical evaluation. We are anticipating being able to determine how frequently new blood vessel growth occurs, and its physiological importance in this evaluation. We are hopeful that this approach will help patients with serious coronary heart disease."

Each year a million Americans undergo coronary surgery or balloon angioplasty to bypass or unclog blocked arteries. However, in some patients the blockages return, restricting the flow of oxygen-rich blood to the heart, which causes severe pain (angina), shortness of breath, and, in many cases, heart attacks. Physicians are hoping that VEGF will produce new blood vessels that will reroute blood around the blocked arteries in the heart to improve blood flow and reduce angina. Proliferation of new blood vessels, known as angiogenesis, occurs naturally during pregnancy and wound healing.

"One of the advantages of this therapy is that it targets direct stimulation of growth of blood vessels in the tissue that is suffering from lack of blood flow, which is more reactive than normal tissue to the action of the growth factor that is administered," says Dr. Emerson Perin, a cardiologist and co-principal investigator in the study at the Texas Heart Institute. "If this therapy proves to be successful, it will be applicable to a large number of patients who may otherwise have limited options for other types of treatment, once the atherosclerotic process has achieved an advanced stage."

In this study, cardiologists administer VEGF through intracoronary and intravenous methods. The first dose is given intracoronary, through a catheter that is inserted in the leg artery that leads from the heart. After the procedure, the patient is discharged from the hospital on the same day and returns to the hospital for three intravenous procedures given over a two-week period.

Patients in the study are randomized to either receive VEGF or a placebo, so that physicians can objectively evaluate VEGF's effectiveness in increasing blood flow to the heart and tolerance to exercise. Several patients at Texas Heart Institute have been treated either with VEGF or the placebo.

One patient, Roy Charles Wilkerson, age 72, says, "I have a family history of heart disease. I am glad to be a part of a study that may help others, including my family members."

Wilkerson has had three bypass surgeries, an angioplasty and stent procedure; however, for the last six months he was experiencing severe chest pain and shortness of breath with exertion. His doctor, Dr. Edward Massin, a cardiologist at Texas Heart Institute and medical director of the transplant service at St. Luke's Episcopal Hospital, had determined that angioplasty and coronary artery bypass procedures were no longer an option for him. In June, Wilkerson received his first dose of VEGF or the placebo. It will be months before Dr. Massin will know if the procedure has helped Wilkerson. Prior to receiving the intracoronary and intravenous infusions, Wilkerson underwent a treadmill test and nuclear perfusion scan, which will be performed again in three months to measure the effectiveness of VEGF.

"Infusion of VEGF is only the latest of numerous approaches we have used at the Texas Heart Institute over the past 20 years to improve blood supply to Mr. Wilkerson's heart," says Dr. Massin. "It is an exciting new option, and we are optimistic that it will give him more active and pain-free years of life. It is too early to know the potential for this therapy. Perhaps we will be able to use it along with angioplasty or bypass surgery or myocardial laser treatments to the benefit of our patients in the future."

All cardiologists at the Texas Heart Institute at St. Luke's Episcopal Hospital are able to use VEGF in the clinical trial. Although cardiologists are optimistic about VEGF, the results are preliminary. A long-term follow-up will be required to ensure the effectiveness and to monitor any side effects of VEGF.

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©2006 Texas Medical Center

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