MRI IDs cardiovascular risk in asymptomatic people

Carotid artery MR imaging may provide physicians with a tool for predicting cardiovascular risk in asymptomatic patients. A study published online March 4 in Radiology found that MRI identified vulnerable plaque features and significantly improved the reclassification of baseline cardiovascular risk.

Anna E. H. Zavodni, MD, of the Sunnybrook Health Sciences Center at the University of Toronto, and colleagues used data from the MESA (Mutli-Ethnic Study of Atherosclerosis) to determine if vulnerable plaque characteristics add to the risk of cardiovascular events beyond traditional risk factors. MESA was a population-based, prospective study that enrolled almost 7,000 adults with no cardiovascular disease between 2000 and 2002.

For this study, Zavodni et al took a sampling of 946 participants with evaluable carotid MR images and ultrasonography who were followed for a mean 5.5 years. They used MRI to evaluate carotid plaque composition and the remodeling index plus ultrasonography to assess carotid wall thickness.

In that group, 6.3 percent of participants experienced an incident cardiovascular event, defined as MI, resuscitated cardiac arrest, angina, stroke and death. Carotid intima-media thickness plus MRI remodeling index, lipid core and calcium in the carotid artery were predictors of cardiovascular events.

Vessel wall thickness was 1.41 mm in participants who had an event vs. 1.08 mm in those who did not and lipid core in the internal carotid artery was present in 47.9 percent of participants who had an event vs. 17.8 percent who did not.

“[A]bout 16 percent more subjects with events were correctly reclassified compared with traditional risk factors when both the carotid remodeling index and the lipid core were used for risk stratification,” they wrote. They added that their results suggest a relationship between plaque identified in carotid MRI and lipid core and subsequent cardiovascular events.

In a release, senior investigator David A. Bluemke, MD, PhD, of the National Institutes of Health Clinical Center in Bethesda, Md., expanded on the potential impact of the study. “The results bolster the use of MRI as a surrogate marker of efficacy in therapeutic studies and point to a role in determining which patients might need more aggressive treatments,” he said. “As risk factor prediction gets better, we will be able to screen more intelligently and use more intensive treatments in those individuals who face a higher risk of cardiovascular events.”