DALLAS, July 23 – The blood clot that causes a heart attack may not act alone. Hidden plaque ruptures may cause further damage, according to a three-dimensional ultrasound study published in today's rapid access issue of Circulation: Journal of the American Heart Association.
About 80 percent of patients recovering from a first heart attack have unstable plaque some distance from the blockages, indicating vulnerability to more heart problems, the study finds.
Researchers believe this is the first study to use high-resolution pictures available with intravascular ultrasound (IVUS) to get three-dimensional (3-D) pictures of the inside the three major coronary arteries during the month following a major event.
After an acute coronary syndrome event such as a heart attack or severe chest pain, there is a high risk of another episode within the year. Previous research has documented a surge in the plaque buildup in the inner lining of arteries (atherosclerosis) after such an event.
This study confirms the notion of overall coronary instability known as "pancoronaritis." "We were very surprised to find that almost four out of five patients present one or more ruptured atherosclerotic plaques besides the culprit lesion," says lead author Gilles Rioufol, M.D., Ph.D, an associate professor in the hemodynamics department of the Cardiologic Hospital, Hospices Civils de Lyon, Lyon, France. "We were even more surprised to see that these distinct ruptured plaques involved all three main coronary trunks.
In fact, for one in eight patients all three main arteries were affected."
These findings also support the hypothesis that inflammation plays a role in heart disease events, says Rioufol.
Atherosclerosis is a progressive condition that develops over many years. Stable plaque that remains in place tends not to cause a heart attack. When the plaque becomes unstable and ruptures, the body responds to that injury with inflammation, which includes forming blood clots to repair the injury. These clots block the artery and cause a heart attack. Plaque rupture or erosion is a prime cause of heart attack and might itself be triggered by inflammation.
Previous researchers had noted accelerated atherosclerosis even when angioplasty was performed. Angioplasty involves inserting a balloon-tipped catheter into the vessel and inflating the balloon to reopen the channel.
In the current study, Rioufol's team visualized 3-D images of 72 arteries in 24 patients referred for angioplasty. IVUS is a 10-minute test in which a tiny ultrasound probe is threaded into a coronary artery during routine coronary angiography.
They found that 19 of the patients (79 percent) had at least one plaque rupture elsewhere than the culprit lesion. Nearly 71 percent of the patients had at least one diagnosed plaque rupture in two of the three arteries; 12.5 percent had at least one rupture in all three arteries. The non-culprit lesions tended to be smaller and less severe.
"At the time of acute coronary syndrome, usually one lesion is clinically active but the entire atherosclerotic coronary tree is destabilized," Rioufol says.
These findings may lead to new screening tools or treatments.
An accompanying editorial says the ability to diagnose vulnerable lesions before they rupture would have "tremendous potential" for heart attack prevention. IVUS and other invasive and noninvasive techniques could allow doctors to assess individual plaques and overall plaque condition.
The editorial writers caution however that the study was limited by the small number of patients studied and the lack of a control group.
Co-authors include: G. Finet, M.D., P.hD.; I. Ginon, M.D.; X. Andre-Fouet, M.D.; R. Rossi, M.D.; E. Vialle, M.D.; E. Desjoyaux, M.D.; G. Convert, M.D.; J.F. Huret, M.D.; and A. Tabib, M.D., Ph.D.
The editorial was written by Paul Schoenhagen, M.D., E. Murat Tuzcu, M.D., and Stephen G. Ellis, M.D.
Materials provided by American Heart Association. Note: Content may be edited for style and length.
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