P2342Plaque characterization by MSCT coronary angiography in native, “true” non-left main coronary bifurcation may be useful for guiding PCI procedures

Abstract

Purpose: Development of atherosclerosis in coronary bifurcation is influenced by its angle, pulsatile flow, curvature and extensive branching. MSCT studies demonstrated that plaque characterization can predict outcomes after PCI in left main bifurcations. We sought to explore the influence of atherosclerotic plaque identification and characterization, by MSCT coronary angiography, on the fate of the side branch (SB) during PCI in native non-left main bifurcations with significant stenoses of both main branch (MB) and SB. Methods: The study included patients with stable coronary artery disease having “true” bifurcations scheduled for intervention. Patients were excluded from the study if they have had an acute coronary syndrome, atrial fibrillation, renal failure, heavy calcifications in the coronary tree or diameter of the SB <2mm or having more than ostial SB stenosis. The scanning was done using 128-row CT scanner according to optimised contrast enhanced protocol. Analysis included vessel diameters, angle measurements, and plaque assessment (location, volume and density) in longitudinal and circumferential cross-sections at the carina level and 5mm proximal and distal to it in the MB, and at the ostium of the SB. Patient underwent “provisional” stenting and proximal optimization treatment in MB, then SB was evaluated and treated if coronary flow was impaired (TIMI<3). Results: Fifty three “true” bifurcations from 52 patients aged 59.9±9.7 years were included in the study (LAD-D1 36/53; Cx-OM 12/53; RCA-PD 5/53 bifurcations). The reference vessel diameter of proximal MB was 4.06±0.46, distal MB 3.25±0.44 and ostium of SB 2.63±0.40mm. Measured bifurcation angles were: proximal MB-SB 152±14°, distal MB-SB 51±18°, proximal-distal MB 157±13°. Plaques at the carina side of SB had mixed fibro-lipid structure (97±78HU) compared to others that were more calcified [proximal MB (lateral 176±156HU, medial 229±243HU), carina (lateral 218±205HU, medial 117±63HU), SB ostium (lateral 147±181HU) and distal MB (lateral 141±146HU, medial 164±163HU) (p<0.001 for all)]. SB compromise, defined as the decrease in TIMI flow bellow 3, occurred in 14 patients (26.4%) and was treated by angioplasty in 4 and by SB stenting in 8 bifurcations. In multivariable regression analysis that included classically recognized predictors of SB compromise as bifurcation angles, diameters of MB and SB, composition and plaque distribution in MB and SB at all levels, only circumferential atherosclerotic plaque in the proximal MB remained an independent predictor [HR 4.513 (95% CI 1.013-20.108)]. Conclusion: Atherosclerotic plaque detection and characterization by MSCT coronary angiography in non-left main “true” bifurcations revealed that SB compromise during PCI was associated with circumferential distribution of atherosclerotic plaques in the proximal segment of MB. This information might be useful in planning PCI procedure.