Predictors of Plaque Rupture Within Nonculprit Fibroatheromas in Patients With Acute Coronary Syndromes

Objectives The study sought to examine the relative importance of lesion location versus vessel area and plaque burden in predicting plaque rupture within nonculprit fibroatheromas (FAs) in patients with acute coronary syndromes. Background Previous studies have demonstrated that plaque rupture is associated with larger vessel area and greater plaque burden clustering in the proximal segments of coronary arteries. Methods In the PROSPECT (Providing Regional Observations to Study Predictors of Events in the Coronary Tree) study 3-vessel grayscale and radiofrequency-intravascular ultrasound was performed after successful percutaneous coronary intervention in 697 patients with acute coronary syndromes. Untreated nonculprit lesion FAs were classified as proximal (<20 mm), mid (20 to 40 mm), and distal (>40 mm) according to the distance from the ostium to the maximum necrotic core site. Results Overall, 74 ruptured FAs and 2,396 nonruptured FAs were identified in nonculprit vessels. The majority of FAs (73.6%) were located within 40 mm of the ostium, and the vessel area and plaque burden progressively decreased from proximal to distal FA location (both p < 0.001). In a multivariate logistic regression model, independent predictors for plaque rupture included the distance from the ostium to the maximum necrotic core site per millimeter (odds ratio [OR]: 0.86; 95% confidence interval [CI]: 0.76 to 0.98; p = 0.02), plaque burden per 10% (OR: 2.05; 95% CI: 1.63 to 2.58; p < 0.0001), vessel area per mm2 (OR: 1.14; 95% CI: 1.11 to 1.17; p < 0.0001), calcium (OR: 0.09; 95% CI: 0.05 to 0.18; p < 0.0001), and right coronary artery location (OR: 2.16; 95% CI: 1.25 to 3.27; p = 0.006). By receiver-operating characteristic analysis, vessel area correlated with plaque rupture stronger than either plaque burden (p < 0.001) or location (p < 0.001). Conclusions Large vessel area, plaque burden, proximal location, right coronary artery location, and lack of calcium were associated with FA plaque rupture. The present study suggests that among these variables, vessel area may be the strongest predictor of plaque rupture among non–left main coronary arteries. (PROSPECT: An Imaging Study in Patients With Unstable Atherosclerotic Lesions [PROSPECT]; NCT00180466)