cCTA Links Progression of Aortic Stiffness, Plaque Extent

Becky McCall

March 09, 2011

March 9, 2011 (Vienna, Austria) — A longitudinal study has demonstrated a link between the progression of arterial stiffness and the progression of coronary atherosclerosis, indicating a need to conduct a routine analysis of patient vascular health that uses aortic stiffness or plaque extent to help stratify patients by risk level.

Shane Oberoi, BS, a medical student at the Medical University of South Carolina in Charleston, presented the study here at the European Congress of Radiology 2011.

"We wanted to evaluate the relationship between changes in aortic stiffness and [changes in] atherosclerotic burden over time, using cardiac computed tomography angiography [cCTA]," Mr. Oberoi told Medscape Medical News. The nature of the relation is vague, although the 2 variables have been shown to be associated in cross-sectional studies.

"To date, arterial stiffness and atherosclerosis have been shown to be associated with each other in cross-sectional studies, but not longitudinal studies, so this is the first study of its kind. Nobody has ever shown a progression between aortic distensibility and coronary atherosclerosis over time before."

Mr. Oberoi and colleagues investigated the relation between vascular stiffness and coronary atherosclerosis or plaque volume by showing that there is a relation between change in aortic distensibility, measured by the Aortic Distensibility Index (ADI), and change in Segment Involvement Score (SIS), an assessment of plaque level across the coronary artery tree according to a modified American Heart Association 15-segment model.

For longitudinal assessment, a patient database search yielded 164 patients who underwent 2 retrospectively electrocardiogram-gated cCTA scans administered 12 ± 10 months apart. Demographic and clinical information was recorded, as was ADI-determined aortic stiffness.

On longitudinal evaluation with cCTA, the investigators observed that the progression of aortic stiffness is associated with the progression of coronary atherosclerosis.

"We found that . . . patients who showed an increase in SIS, or those with increased plaque in their arteries, also showed a greater decrease in the change in aortic distensibility (< .001). This was evaluated using a formula that calculates the change in the cross-sectional area of the aorta at systole and diastole relative to the pulse pressure. There is an inverse relationship between change in SIS and change in ADI," explained Mr. Oberoi.

The researchers also found that in patients with more time between scans, a greater increase in SIS was more likely, which precipitated a greater decrease in ADI score (≤ .0125).

"The point is that if clinicians do routine analysis of vascular health of the patient, such as routine analysis of their ADI or SIS, their progress can be tracked and risk can be stratified. Treatment decisions can then be made based on this assessment, depending on their rate of worsening," Mr. Oberoi explained.

"This is still early stage, but the next step for our lab is to conduct an outcome study to evaluate what happens to patients who progressively get worse. If we can increase our patient numbers, then we would have an even stronger link. It might help to identify at-risk patients using other clinical indications in the first instance, and to later assess using our method," concluded Mr. Oberoi.

Vivek Raman, MD, consultant radiologist at Spire Sussex Hospital in Hastings, United Kingdom, said he is aware of the need for longitudinal studies in the literature to assess the prognostic relevance of wall calcium and stiffness.

"This has been done by this group, and as the presenter says himself, routine analysis of patient vascular health through these methods may provide insights into assessing response to treatment, such as antihypertensive therapy," Dr. Raman said.

Mr. Oberoi and Dr. Raman have disclosed no relevant financial relationships.

European Congress of Radiology (ECR) 2011: Abstract B-468. Presented March 5, 2011.

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