Comparison of carotid plaque tissue characteristics in patients with acute coronary syndrome or stable angina pectoris: assessment by iPlaque, transcutaneous carotid ultrasonography with integrated backscatter analysis

BACKGROUND The association of the tissue characteristics of carotid plaques with coronary artery disease has attracted interest. The present study compared the tissue characteristics of carotid plaques in patients with acute coronary syndrome (ACS) with those in patients with stable angina pectoris (SAP) using the iPlaque system, which is based on ultrasound integrated backscatter. METHODS AND RESULTS Carotid ultrasound examinations were performed in 26 patients with ACS, and 38 age- and gender-matched patients with SAP. Neither plaque area nor maximal intima-media thickness differed significantly between the two groups. However, the average integrated backscatter value within the plaque was greater in the ACS patients than in the SAP patients. iPlaque analysis revealed that the percentage blue area (lipid pool) was greater in the ACS patients than in the SAP patients (43.4 ± 11.2 vs 18.3 ± 10.3%, p < 0.0001), and that the percentage green area (fibrosis) was lower in the ACS than in the SAP patients (7.5 ± 7.5% vs 20.7 ± 11.7%, p < 0.0001). CONCLUSIONS The lipid component of carotid plaques is greater in ACS patients than in SAP patients. Our iPlaque system provides a useful and feasible method for the tissue characterization of carotid plaques in the clinical setting.