Coronary artery disease (often referred to as heart disease) is a condition in which some areas of the heart are narrowed and hardened. It's usually caused when plaque accumulates along the inner walls of the arteries. Soft formations of plaque may break open, or fracture, releasing some of the inner contents of the deposit into the bloodstream. The body senses this as an "injury" and may send blood clots to cover and seal the area. A clot can block the flow of blood through the artery.

Sometimes plaque hardens into a thick deposit. The thickened area can impede blood flow through that part of the artery. The plaque can also accumulate enough to completely close off the artery and obstruct blood flow.

When an artery that feeds the heart becomes blocked, cells in the area below the point of blockage are deprived of oxygen and begin to die. This is a heart attack, or myocardial infarction. Medical intervention is needed to prevent permanent damage or death.

According to the American Heart Association, about 15.8 million people in the U.S. have coronary artery disease. This year alone, 700,000 Americans will have a heart attack. Heart disease is the leading cause of death in this country, killing 452,327 men and women in 2004. Many heart attack survivors face higher risk of health complications, like heart failure (an inability of the heart to pump enough blood to meet the needs of the body) and arrhythmia (irregular heart rhythm).

Treating Coronary Artery Disease: Angioplasty

One of the treatments for narrowed coronary arteries is angioplasty. A balloon-tipped catheter is inserted into a blood vessel in the leg. Then, using X-rays for guidance, the catheter is fed through the circulatory system up to the point of narrowing in the heart. Next, the balloon is inflated. As the balloon expands, it compresses the plaque against the walls of the artery. A device, called an expandable stent, may be placed in the area to hold the plaque against the wall and keep the artery open. Finally, the balloon is deflated and the catheter is withdrawn.

Angioplasty is now performed about three times more often than coronary artery bypass surgery. In 2004, there were 1.285 million angioplasties performed in the U.S. and 427,000 bypass surgeries.

Stem Cells for the Heart

After a heart attack, the body tries to repair some of the heart muscle damage. Stem cells are mobilized from the bone marrow and sent to the site. These stem cells have the capability to develop into whatever cell is needed by the body - in this case, heart muscle cells.

Researchers are now trying to see if placing additional stem cells in the heart can improve long-term function of the heart muscle. The trial is called the "Amorcyte Myocardial Repair Study - A Phase I Trial of Intra-Coronary Infusion of Bone Marrow Derived Autologous CD34+ Selected Cells in Patients with Acute Myocardial Infarction (AMRS)." It is a Phase I study.

Arshed Quyyumi, M.D. Cardiovascular Researcher at Emory Crawford Long Hospital, is the principal investigator of the study. He explains when a heart attack patient has angioplasty, he/she is assessed for heart muscle damage. If damage is found, the patient will be asked to participate in the study. Half of the participants will be randomly assigned to receive treatment. The others will be followed.

For those in the treatment group, a bone marrow aspiration is performed between 6 and 9 days after the heart attack. A small amount of bone marrow is taken from the back of the hip bone and processed. Specialized stem cells, called CD34 positive (CD34+) cells are removed. The next day, the patient is taken back into the catheterization lab. A balloon-tipped catheter is once again snaked through the circulatory system to the previously treated area of the artery. The balloon is inflated and the patient's stem cells are infused directly into that area of the artery. The balloon temporarily halts the flow of blood to allow the stem cells to better permeate the damaged area of heart muscle. The balloon is then deflated and the catheter is withdrawn.

Researchers hope the stem cell treatment can help repair some of the heart muscle damage caused by the heart attack. Quyyumi says this may occur in one of two ways. First, the stem cells may encourage growth of new blood vessels into the portion of the heart muscle that has been injured, but still able to recover. Second, the treatment may halt the death of some of the heart muscle cells.

In addition to Emory, the study is taking place at Texas Heart Center in Houston and Vanderbilt Hospital in Nashville. Patients who have had heart attacks must contact the researchers within four to five days to be considered for the study. For more information, call (404) 783-5908. The study is being funded by the biotech company, Amorcyte, that is performing the stem cell separation.

In addition to Emory, the current study is taking place at Texas Heart Center in Houston and Vanderbilt Hospital in Nashville. Patients who have had heart attacks must contact the researchers within four to five days to be considered for the study. For more information, call (404) 783-5908. Information about the trial is also available by logging on to http://www.clinicaltrials.gov. At the search box, type in the trial ID #: NCT00313339.

For general information on heart disease or heart attack:

American Heart Association

National Heart, Lung and Blood Institute