Static and serial assessments of coronary arterial remodeling are discordant: an intravascular ultrasound analysis from the Reversal of Atherosclerosis with Aggressive Lipid Lowering (REVERSAL) trial.

BACKGROUND: Arterial remodeling is a major determinant of the clinical manifestations of coronary artery disease. Assessment of arterial remodeling with intravascular ultrasound (IVUS) used to rely on comparing the external elastic membrane (EEM) areas of lesion and reference sites at a single time point (static assessment). Recently, performance of serial IVUS provided the opportunity for direct assessment of remodeling. Our aim was to study the concordance of the static and serial methods.
METHODS: We identified 210 focal coronary lesions on the baseline IVUS interrogations of the REVERSAL trial. A follow-up IVUS was performed at 18 months. Static assessment was performed by calculating the remodeling index (RI) (lesion EEM area / reference EEM area) and serial assessment by comparing the changes in atheroma and EEM areas at follow-up.
RESULTS: Using the serial method, there was a 1.24 mm2 increase in EEM area for every 1 mm2 increase in atheroma area at the lesion site, which was indicative of expansive (overcompensatory) remodeling. By using the static method, the RI was paradoxically lower at follow-up (1.062 +/- 0.15 at baseline vs 1.027 +/- 0.14 at follow-up, P < .001), indicating a trend toward constrictive remodeling. The reason for decreased RI at follow-up was the relatively larger expansion of the EEM areas at the reference sites.
CONCLUSIONS: Static and serial assessments of arterial remodeling are discordant. This is due to concomitant remodeling of the reference sites used in the static assessment. Intravascular ultrasound performed at a single point in time does not reflect the dynamic remodeling response.