Objectives: The purpose of this study was to correlate adverse events at long-term follow-up in patients after an acute coronary syndrome with coronary plaque characteristics derived from simultaneous evaluation of their mechanical and compositional properties using virtual histology (intravascular ultrasound virtual histology) and palpography.

Background: Fibroatheroma is the plaque morphology with the highest risk of causing adverse cardiac events. Palpography can potentially assess the local mechanical plaque properties with the possibility of identifying fibroatheroma with the highest risk of rupture.

Methods: A total of 114 patients with acute coronary syndrome from the PROSPECT (Providing Regional Observations to Study Predictors of Events in the Coronary Tree) trial underwent a single ultrasound imaging investigation of their 3 coronary vessels with the co-registration of intravascular ultrasound virtual histology and palpography. Major adverse cardiac events (MACE) (cardiac death, cardiac arrest, myocardial infarction, or unstable or progressive angina) were collected up to a median follow-up of 3.4 years and adjudicated to originally treated culprit versus untreated nonculprit lesions.

Results: In total, 488 necrotic core-rich plaques were identified and subclassified as thin-cap fibroatheroma (n = 111), calcified thick-cap fibroatheroma (n = 213), and noncalcified thick-cap fibroatheroma (n = 164) and matched to their co-registered palpography data. A total of 16 MACE, adjudicated to untreated nonculprit lesions, were recorded at follow-up. In patients in whom MACE developed, fibroatheroma were larger (plaque area 10.0 mm(2) [range: 8.4 to 11.6 mm(2)] vs. 8.2 mm(2) [range: 7.7 to 8.8 mm(2)] (p = 0.03) compared with patients who were MACE free. By palpography, the maximum and the density strain values did not differ between the varying subtypes of fibroatheroma of patients with or without MACE during follow-up.

Conclusions: In acute coronary syndromes, patients treated with stents and contemporary pharmacotherapy, palpography did not provide additional diagnostic information for the identification of fibroatheroma with a high risk of rupture and MACE during long-term follow-up. (Providing Regional Observations to Study Predictors of Events in the Coronary Tree [PROSPECT]: An Imaging Study in Patients With Unstable Atherosclerotic Lesions; NCT00180466).