Virtual histology study of atherosclerotic plaque composition in patients with stable angina and acute phase of acute coronary syndromes without ST segment elevation.

Introduction: Rupture of vulnerable atherosclerotic plaques is the cause of most acute coronary syndromes (ACS). Postmortem studies which compared stable coronary lesions and atherosclerotic plaques in patients who have died because of ACS indicated high lipid-core content as one of the major determinants of plaque vulnerability.

Objective: Our primary goal was to assess the potential relations of plaque composition determined by IVUS-VH (Intravascular Ultrasound -Virtual Histology) in patients with stable angina and subjects in acute phase of ACS without ST segment elevation.

Methods: The study comprised of 40 patients who underwent preintervention IVUS examination.Tissue maps were reconstructed from radio frequency data using IVUS-VH software.

Results: We analyzed 53 lesions in 40 patients. Stable angina was diagnosed in 24 patients (29 lesions), while acute phase of ACS without ST elevation was diagnosed in 16 patients (24 lesions). In the patients in acute phase of ACS without ST segment elevation IVUS-VH examination showed a significantly larger area of the necrotic core at the site of minimal lumen area and a larger mean of the necrotic core volume in the entire lesion comparing to stable angina subjects (1.84+/-0.90 mm2 vs. 0.96+/-0.69 mm2; p<0.001 and 20.94+/-15.79 mm3 vs. 11.54+/-14.15 mm3; p<0.05 respectively).

Conclusion: IVUS-VH detected that the necrotic core was significantly larger in atherosclerotic lesions in patients in acute phase of ACS without ST elevation comparing to the stable angina subjects and that it could be considered as a marker of plaque vulnerability.