MRI measures of aortic atherosclerosis predict cardiovascular events

Patients with a thicker aorta as measured by MR imaging face increased risk for future adverse cardiovascular events, according to a study published online June 18 in Radiology.

Aortic atherosclerosis, which has a long subclinical phase, remains a clinical dilemma. “Prior studies in which aortic atherosclerosis has been related to coronary artery disease, cerebrovascular disease, and peripheral arterial disease have provided conflicting results and are limited by the examination of only calcified or discrete raised plaques,” wrote Christopher D. Maroules, MD, from the department of radiology at University of Texas Southwestern Medical Center in Dallas, and colleagues.

Researchers have used CT and spine x-rays to evaluate aortic calcification, a model that has two downsides, according to the researchers. They expose patients to ionizing radiation and are limited to calcified plaque.

Maroules and colleagues mined data from the Dallas Heart Study, a multiethnic, population-based probability sample in which participants underwent MR assessment for abdominal aortic wall thickness and aortic plaque prevalence. They aimed to determine whether mean aortic wall thickness (MAWT) and plaque burden could predict future adverse cardiovascular events.

The researchers reviewed MAWT and aortic plaque measurements derived from 1.5 T MR scans of 2,122 participants in the Dallas Heart Study. They monitored participants for cardiovascular death, nonfatal cardiac events and nonfatal extracardiac vascular events for a mean duration of 7.8 years.

The mean age of the study population was 44 years, and 56 percent were women. A total of 17 percent of participants had both prevalent aortic plaque and highest quartile MAWT, Maroules et al reported. Twenty-one percent had aortic plaque alone and 8 percent had highest-quartile MAWT alone.

Statistical analysis showed MAWT independently associated with composite cardiovascular events. Although aortic plaque burden was not associated with increased risk for composite events, it was linked with significantly increased risk for nonfatal extracardiac vascular events.

“These results validate the prognostic implications of these subclinical aortic atherosclerosis measures and clarify the reliance of these measures for specific clinical manifestations of cardiovascular disease,” wrote Maroules and colleagues.

Although the research showed a connection between a thicker aorta and increased risk of cardiovascular events, Maroules and colleagues do not encourage screening for global cardiovascular risk by using only these aortic measures.

The researchers acknowledged several limitations to the study, including a relatively small number of cardiovascular events and a focus on a single MR pulse sequence. They have planned future studies to examine the prognostic value of various plaque components.