PROSPECT II: High-Risk Plaques Common in Significant Coronary Lesions

Angiographically intermediate but physiologically significant coronary lesions were more likely to have high-risk vulnerable plaque features, such as large plaque burden or high lipid content, compared with non-physiologically significant stenoses among patients with recent myocardial infarction, according to the results of a PROSPECT II substudy.

The PROSPECT II study included patients with recent MI who had all flow-limiting coronary lesions treated. Three-vessel imaging was performed with combined near-infrared spectroscopy (NIRS) and intravascular ultrasound (IVUS) catheter; non-culprit lesions were identified and assessed. The study found that highly lipidic lesions and large plaque burden were associated with non-culprit lesion-related MACE.

In this substudy, the research assessed if there was an association between pressure wire based physiological assessments and NIRS-IVUS measures of plaque vulnerability. Looking at 898 patients from the study, they identified 319 angiographically intermediate lesions in 275 patients with matched NIRS/IVUS and instantaneous wave-free ratio (iFR) or fractional flow reserve (FFR) measurements.

About one-third (30.1%) of lesions were physiologically significant and about two-thirds (69.9%) were not. The researchers identified characteristics that were more common in physiologically significant lesions compared with those that did not include minimal lumen area less than or equal to 4.0 mm² (96.9% vs 83.9%), plaque burden greater than or equal to 70% (92.7% vs. 71.3%) and maximum lipid core burden index in any 4 mm segment of the lesion greater than or equal to 324.7 (57.0% vs 45.4%).

Multivariable analysis in the 319 lesions showed that lesion location in the left anterior descending artery, small minimal lumen area, and larger plaque burden was independently associated with physiologic significance. However, lipid content and distance from the ostium to the minimal lumen area were not independently associated with physiological significance.

“Our data confirm the findings from previous studies demonstrating that hemodynamically significant lesions are more likely to have high-risk vulnerable plaque features,” the researchers wrote. “The present study suggests a worse prognosis if complete revascularization is not performed after MI in non-culprit lesions with vulnerable plaque features.”