Objective To investigate and compare the pattern of instent neointimal formation and native atherosclerosis in the coronary bifurcation lesions by volumetric analysis using systematic intravascular ultrasound (IVUS).

Methods This study examined 102 native coronary artery bifurcation lesions and 51 post-stenting bifurcation lesions treated with drug-eluting stents using the T-stenting technique at 9-month follow-up IVUS images for both main vessel and side branch. Three interested segments were analysed: proximal main vessel (MVp) ostium, distal main vessel (MVd) and side branch ostium (SBo). At each segment, four quadrant analysis was performed per 1 mm by measuring the vessel area (stent area in the post-stenting lesions), lumen area and calculating the plaque area for volumetric analysis.

Results In the plaque group, the plaque volume differed significantly between the four quadrants (P < 0.001). In all three segments (MVp, MVd and SBo), the plaque volume was largest in the abcarinal quadrant, followed by the myocardial, epicardial, and carinal quadrants, respectively. The myocardial quadrant had a greater plaque volume than the epicardial quadrant in all three segments (MVp P = 0.001, MVd P < 0.001, SBo P < 0.001, separately).

When the left main (LM) bifurcation (n = 38) was analysed separately, the abcarinal quadrant still had the largest plaque volume and the carinal quadrant the least in all three segments, while the epicardial and myocardial quadrant did not differ in the MVp (P = 0.99). In the MVd and SBo, the plaque volume of myocardial quadrant was still significantly greater than the epicardial quadrant (P < 0.001, P = 0.005, separately).

In the neointima group, the neointimal volume differed significantly in the MVp and MVd (P = 0.002, P = 0.002, separately), while the four quadrants did not differ in the SB (P = 0.281). In the MVp and MVd, the neointimal volume was larger in the abcarinal than the carinal quadrant (in MVp, 4.8 mm3 [IQR 2.7.6.3 mm3] vs.2.1 mm3 [IQR 0.5.3.9 mm3], P < 0.001; in MVd, 2.9 mm3 [IQR 1.9.4.3 mm3] vs.1.8 mm3 [IQR 1.1.3.2 mm3], P < 0.001).

When comparing the eccentricity indices between plaque and neointima groups, there was no difference in the MVp, while the neointima group was significantly smaller than plaque group in the MVd (1.6 [IQR 0.8, 2.8] vs. 4.7 [IQR 2.1, 8.7], P < 0.001) and SBo (1.0 [IQR 0.7, 3.1] vs. 3.1 [IQR 1.9, 4.6], P = 0.001).

Conclusions The distribution of neointimal proliferation and seems to have a similar pattern to that of atherosclerotic plaque in native coronary arteries, particularly in the main vessel, but the trend is less prominent.