A drug commonly used during invasive heart procedures not only helps maintain blood flow through the large blood vessels that have been enlarged during the procedure by balloons and metal tubes, but also preserves blood flow through the smaller blood vessels downstream that may become blocked by debris. This helps to restore much needed oxygen supply directly to heart muscle, according to C. Michael Gibson, MD, UCSF chief of interventional cardiology, director of the Core Angiographic Laboratory at UCSF and lead author of the study.
Gibson presented the results at the American Heart Association in New Orleans, Louisiana, on Sunday, November 12.
"During invasive heart procedures many small blood clots may be released during the placement of a tube or stent in the artery, and these small clots may in turn float downstream and block the small vessels or capillaries that supply blood to the heart muscle itself. In order to prevent irreversible injury to the heart that can occur following stenting, it is critical that this complex network of very small blood vessels that supply oxygen to the heart muscle remain intact," explained Gibson. "Our study clearly demonstrates that use of the drug eptifibatide at the time of stent placement helps preserve the integrity of the microvasculature and blood flow into the heart muscle."
Eptifibatide (Integrilin®) blocks the receptors on platelets, components in the blood that are responsible for coagulation. This reduces clot formation that can lead to heart attack or death, said Gibson. Use of eptifibatide significantly improved the ability of the heart to speed up its blood flow in large arteries by 39 percent when compared with placebo. It improved the speed at which blood entered the microvasculature in the heart muscle by 84 percent compared to placebo, explained Gibson. Improving the entry of blood into the heart muscle preserves blood supply to the previously oxygen-starved heart muscle in patients undergoing angioplasty, he said.
Nearly 600,000 angioplasty procedures are performed in the United States each year. The procedure is used to stretch the walls of narrowed blood vessels in the heart that limit the supply of oxygen to heart muscle. More than six out of ten procedures involve the placement of intracoronary stents, metal mesh structures that hold the heart arteries open after the procedure. Although angioplasty and intracoronary stenting are generally successful at restoring blood flow and preventing the collapse of the artery, the use of a stent into the artery wall can result in the clumping of platelets and the development of blood clots. A clot can obstruct blood flow through both large and small arteries.
Investigators evaluated angiograms of 65 patients taken before and after stent placement to determine the extent of and speed of blood flow through the network of very small blood vessels that supply oxygen to the heart muscle. With computer assisted analysis, investigators were able to measure how bright the heart muscle became (due to a surge of dye indicating increased blood flow to the microvasculature) after use of the eptifibatide.
Co-investigators in the study were David Cohen, MD, assistant professor of medicine, Harvard University and James E. Tcheng, MD, associate professor of medicine, Duke University.
Integrilinâ was developed and is marketed in the United States by COR Therapeutics, Inc., South San Francisco and Key Pharmaceuticals, Inc., Kenilworth, New Jersey. Both companies funded the study.