UCI researchers uncover how plaque in neck artery leads to stroke-inducing blood clots

Findings press need for early treatment to help prevent strokes

A UC Irvine Stroke Center study reveals how plaque in the main neck artery plays a critical role in creating blood clots that greatly increase the risk of stroke.

Dr. Mark Fisher, director of the UCI Stroke Center, and colleagues found that in the carotid artery, the primary source of blood to the brain, plaques form lesions that support the growth of the stroke-causing blood clots, which can either block the artery or break off and travel into the brain.

The findings suggest an increased need for early identification and treatment of this plaque growth for people who are at risk for stroke. Strokes are the leading reason for disability and the third leading cause of death in the United States today, and 80 percent of these strokes are caused by blood clots. Study results appear online in Stroke, a peer-reviewed journal of the American Heart Association (www.strokeaha.org). “Plaque growth in the carotid artery is the most important surgically correctable cause of stroke,” said Fisher, the study leader. “However, there has been only limited information about the nature of these plaque lesions, and this study provides some of the best evidence yet showing their link to stroke.”

The work of Fisher and his colleagues shows the importance of several pathologic features of the plaques that produce stroke symptoms. Extensive analyses were performed on surgical specimens from two of the most important clinical trials in the history of stroke research: the North American Symptomatic Carotid Endarterectomy Trial and the Asymptomatic Carotid Atherosclerosis Study. Fisher’s study constitutes the only formal interaction between these two historically important studies.

Fisher and his colleagues found that carotid-artery plaques most likely to cause stroke first develop depressions in their surface called ulcerations. Blood can pool in these ulcerations and ultimately form into clots. This suggests that early detection and treatment of carotid-artery plaques before these ulcerations grow can benefit people who exhibit stroke risk factors such as hypertension, elevated cholesterol, diabetes or a previous stroke. “As carotid-imaging technologies improve, identification of both ulceration and blood-clot development will assist in the decision for removal of carotid-artery plaques,” said Fisher, professor and chair of neurology in the UCI School of Medicine.

Dr. Annlia Paganini-Hill, Aldana Martin and Dr. Michele Cosgrove of the University of Southern California in Los Angeles; Dr. James F. Toole of the Wake Forest School of Medicine in Winston-Salem, N.C.; Dr. Henry J.M. Barnett of the John P. Robarts Research Institute in London, Ont., and Dr. John Norris of the St. George Hospital Medical School in London, England, assisted with the study. The National Institutes of Health provided funding support.

The UCI Stroke Center’s clinical activities are located in the UCI Medical Center, which is the first academic medical center in the nation to be certified by the Joint Commission on Accreditation of Healthcare Organizations for stroke care.

About the University of California, Irvine: The University of California, Irvine is a top-ranked public university dedicated to research, scholarship and community service. Founded in 1965, UCI is among the fastest-growing University of California campuses, with more than 24,000 undergraduate and graduate students and about 1,400 faculty members. The second-largest employer in dynamic Orange County, UCI contributes an annual economic impact of $3 billion.