The impact of coronary artery disease risk factors on intravascular ultrasound-derived morphologic indices of human coronaries.

Objective: The relationship of intravascular ultrasound (IVUS)-derived measurements of atherosclerotic plaque to various coronary artery disease (CAD) risk factors is not well known. The purpose of this study was to examine the relationship of percent coronary luminal stenosis by IVUS to other IVUS measures of CAD, as well as the relationship of common IVUS measures of CAD to traditional CAD risk factors. We hypothesized that one or more IVUS measures of CAD might relate more strongly to CAD risk factors than does percent luminal coronary stenosis. Methods: The records of 897 consecutive patients (57% men, mean age 62 years) who underwent IVUS investigation of their coronary arteries from 1996 through 2001 were retrospectively reviewed. IVUS was performed using a 20-MHz probe (Jomed, Rancho Cordoba, CA) and a manual pull-back technique to image the coronary arteries. Coronary artery remodeling ratio—i.e., the ratio of coronary lesion external elastic membrane cross-sectional area (EEM CSA) to proximal reference artery EEM CSA; plaque burden—i.e., plaque plus media CSA divided by EEM CSA; calcium arc; and percent stenosis of luminal cross-sectional area were measured by a single reader. Results: Percent area stenosis, the most commonly used IVUS parameter, did not correlate with the other three IVUS-derived parameters, nor was it related to any of the CAD risk factors considered. In contrast, remodeling ratio was directly correlated with plaque burden (r = 0.22, P < 0.001), but inversely related to calcium arc (r =−0.13, P = 0.01). IVUS plaque burden was significantly correlated with male gender (P < 0.0001) and diabetes mellitus (DM) (P = 0.003). In multivariate analyses including age, gender, and CAD risk factors, plaque burden was significantly associated with age, male gender, and DM, but not with chronic renal failure, hypertension, or hypercholesterolemia. The multivariate model also revealed that the calcium arc was significantly associated with male gender and age. These IVUS findings provide anatomic documentation that the traditional CAD risk factors relate more strongly to plaque burden than to percent coronary arterial luminal narrowing.