Tissue characteristics of non-culprit plaque in patients with acute coronary syndrome vs. stable angina: a color-coded intravascular ultrasound study

Patients with acute coronary syndrome (ACS) are thought to have multiple vulnerable coronary plaques. We analyzed non-culprit plaques in patients with ACS vs. stable angina pectoris (SAP) by means of color-coded intravascular ultrasound (iMap-IVUS). Patients who underwent percutaneous coronary intervention were divided into an ACS group (n = 39) and an SAP group (n = 35). Non-culprit lesions were imaged by 40-MHz iMap-IVUS, and the plaque characteristics were compared between the two groups. Plaque volume was similar between the two groups. The fibrotic volume (%FV) was less in the ACS group than in the SAP group (70.2 ± 10.4 vs. 76.5 ± 7.2 %, respectively, P < 0.01), whereas the lipidic volume and necrotic volume (%NV) were greater in the ACS group (8.2 ± 0.4 vs. 6.3 ± 0.4 %, P < 0.01; 15.1 ± 7.9 vs. 9.9 ± 4.8 %, P < 0.01). An inverse correlation was found between %FV and total plaque volume (ACS group: r = −0.52, P < 0.01; SAP group: r = −0.31, P = 0.01), and a positive correlation was found between %NV and total plaque volume (ACS group: r = 0.56, P < 0.01; SAP group: r = 0.41, P < 0.01). Furthermore, the slope of the regression line showing the relation between plaque volume and necrotic volume was significantly steeper for the ACS group than for the SAP group (P < 0.05). Non-culprit lesions are particularly vulnerable in ACS patients. Non-culprit lesions are particularly vulnerable in ACS patients. Furthermore, the stronger correlation between plaque volume and %NV was observed in ACS patients than in SAP patients.