News | January 21, 2011

PROSPECT: IVUS Assesses Risk of Future Vulnerable Plaque Ruptures

A comparison showing the same lesions imaged with grayscale IVUS (left), and color-coded virtual histology that characterizes the plaque.

Intravascular ultrasound (IVUS) enabled physicians to more accurately assess the risk of individual blockages than the use of the current standard of angiographic imaging alone, according to a new study. The results from the PROSPECT (Providing Regional Observations to Study Predictors of Events in the Coronary Tree) study were published this week in The New England Journal of Medicine.

Investigators used grayscale IVUS and Volcano Corporation’s Virtual Histology (VH)-IVUS tissue characterization software to evaluate suspected vulnerable plaques in the coronary arteries.

“The landmark PROSPECT study has confirmed two key principles that will be relevant as we continue to innovate and improve our treatment of cardiovascular disease,” said Gregg W. Stone, M.D., the study’s principal investigator and professor of medicine at Columbia University College of Physicians and Surgeons, director of Cardiovascular Research and Education at the Center for Interventional Vascular Therapy at New York-Presbyterian Hospital/Columbia University Medical Center. “First, angiographic guidance alone is not a good predictor of future events; grayscale intravascular ultrasound is much better than angiography at determining the severity of plaque, and which blockages are most likely to cause future events. Second, all coronary artery disease is not the same, and differences in underlying tissue type can in fact change the risk profile of a lesion. Some blockages are more active and can quickly progress to a clinical event. Other blockages are more stable, and when combined with proper medical therapy, have an extremely low risk of causing a future event. For the first time, we have been able to prospectively identify these lesions both by size and by tissue type using VH-IVUS.”

The PROSPECT study, which was funded by Abbott and Volcano, is the first and only natural history study that tracked the clinical outcomes, hospital readmissions and subsequent coronary events of patients with acute coronary syndrome (ACS). The study followed 700 U.S. and European patients with ACS over three years. The investigators assessed these patients’ coronary arteries by taking very detailed measurements and interior images of all three arteries. The PROSPECT study showed that of the 55 imaging parameters measured, grayscale IVUS and VH-IVUS identified the only individual parameters that could statistically predict lesion risk for future clinical events. When combined together, grayscale IVUS and VH-IVUS uncovered lesion characteristics that PROSPECT showed predict the highest lesion risk for future clinical events.

“The need to improve patient care and reduce cost has led to more personalized medicine,” Scott Huennekens, Volcano’s president and CEO. “For personalized medicine to work, we must rely on better diagnostic tools to determine which patients will or will not benefit from therapy. PROSPECT shows us that we can go beyond the limitations of a two-dimensional X-ray and better separate these blockages into higher risk and lower risk.”

The investigators found that certain high-risk lesions, including those with a relatively small lumen area and a large amount of plaque and a significant amount of dead tissue or necrosis near the lumen as identified by VH-IVUS, had an almost 20 percent risk of a cardiac event within three years. These lesions were classified as “predictive” by the investigators. Conversely, certain low-risk lesions where that same necrotic tissue was not present in the study had a significantly lower event rate of only 0.6 percent out to three years. These lesions were termed “protective” by the investigators.

For more information: www.nejm.org

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