Screening of ruptured plaques in patients with coronary artery disease by intravascular ultrasound

Aim-To visualise the characteristics of ruptured plaques by intravascular u ltrasound (IVUS) and to correlate plaque characteristics with clinical symp toms to establish a quantitative index of plaque vulnerability. Methods-144 consecutive patients with angina were examined using IVUS. Rupt ured plaques, characterised by a plaque cavity and a tear on the thin fibro us cap, were identified in 31 patients (group A), of whom 23 (74%) presente d with unstable angina. Plaque rupture was confirmed by injecting contrast medium filling the plaque cavity during IVUS examination. Of the patients w ithout plaque rupture (group B, n = 108), only 19 (18%) had unstable angina . Results-No significant differences were found between groups A and B in rel ation to plaque and vessel area (p > 0.05). Mean (SD) per cent stenosis in group A was less than in group B, at 56.2 (16.5)% v 67.9 (13.4)%; p < 0.001 . Area of the emptied plaque cavity in group A (4.1 (3.2) mm(2)) was larger than the echolucent zone in group B (1.32 (0.79) mm(2)) (p < 0.001). The p laque cavity to plaque ratio in group A (38.5 (17.1)%) was larger than the echolucent area to plaque ratio in group B (11.2 (8.9)%) (p < 0.001). The t hickness of the fibrous cap in group A was less than in group B, at 0.47 (0 .20) mm v 0.96 (0.94) mm; p < 0.001. Conclusions-Plaques seem to be prone to rupture when the echolucent area is larger than 4.1 (3.2) mm(2), when the echolucent area to plaque ratio is g reater than 38.5 (17.1)%, and when the fibrous cap is thinner than 0.7 mm. IVUS can identify plaque rupture and vulnerable plaques. This may influence patient management and treatment.