A comparison of the distribution of necrotic core in bifurcation and non-bifurcation coronary lesions: an in vivo assessment using intravascular ultrasound radiofrequency data analysis.

Aims: High-risk plaques are prone to develop at the site of coronary vessel bifurcations. The distribution of necrotic core at bifurcation lesions (BL) is known, however, little has been described on the necrotic core distribution in non-BLs. Therefore we compared the distribution of necrotic core between BL and non-BLs in coronary arteries using IVUS-VH imaging. Methods and results: A total of 129 patients (112 non-BL and 108 BL) were included. The lesions were divided into upstream and downstream segments according the location of the minimum lumen area (MLA) within the plaque. In BLs, compositional analysis showed no differences between the three segments. The necrotic core in contact with the lumen that was located in the downstream segment was significantly larger. While in non-BLs, this was not significantly different between segments. Plaque burden in BLs was 56.60 +/- 5.79% vs. 55.50 +/- 4.54% in non-BLs, p=0.04. Mean necrotic core area was larger in BLs 0.84 +/- 0.55mm(2) vs. 0.70 +/- 0.49mm(2), p=0.048. Mean percentage necrotic core was 15.48 +/- 8.02% vs. 14.51 +/- 7.64%, p=0.37. There was a trend towards a greater content of necrotic core in contact with the lumen in BLs. The percentage of frames with a major confluent pool of necrotic core in contact with the lumen >10% in BLs was 11.78 +/- 17.18 vs. 8.95 +/- 17.86 in non-BLs, p=0.065. There was a statistically significant difference in the frequency of IVUS derived thin capped fibroatheromas between bifurcation lesions 20 vs. 13 in non-bifurcation lesions, p=0.03. Conclusions: Bifurcation lesions appear to have a larger plaque burden with a different plaque composition compared to non-bifurcation lesions. This may partly explain the adverse outcomes seen following treatment of bifurcation lesions in contemporary practice.