Coronary risk factors and coronary atheroma burden at severely narrowing segments

While only few data exist correlating cardiovascular risk factors with volumetric measurements of coronary atheroma burden in patients with coronary artery disease, a recent report using intravascular ultrasound (IVUS) demonstrated independent predictors of atherosclerotic burden in a native coronary artery with relatively mild narrowing (20-50% diameter stenosis by visual estimation). The purpose of this study was to examine whether cardiovascular risk factors can predict atherosclerotic burden at severely narrowing segments (>50% diameter stenosis).

Patients who met the criteria (high-quality, automated pull-back IVUS images of severely narrowing segments prior to intervention) were identified from the IVUS database of the Cardiovascular Core Analysis Laboratory at Stanford University. Using commercially available planimetry software, lumen and vessel inside external elastic membrane areas were manually traced at every 0.5-mm interval in diseased segments. Using Simpson's method, vessel, lumen, and plaque (vessel minus lumen) volumes were calculated, and average area was calculated as volume data divided by length. Percent plaque volume was computed as plaque volume divided by vessel volume. Multiple linear regression analysis with backward selection was used to determine the risk factors for atherosclerotic burden.

For percent plaque volume, diabetes or hypertension were predictors of more severe disease. For average plaque area, male gender or diabetes were predictors of more severe disease. These variables were also independent predictors in multivariate regression models.

Male gender, hypertension, and diabetes are also strong independent predictors of atherosclerotic burden in coronary disease patients, though analyzed segments and disease severity were different.