Coronary left main and non-left main bifurcation angles: How are the angles modified by different bifurcation stenting techniques

Background: Investigation of the correlation between bifurcation angles and outcomes is limited with discordant results. The aim of this study is to investigate left main (LM) and non-left main (N-LM) bifurcation angles and their modification after percutaneous coronary intervention (PCI). Measurement of all three angles adds to our understanding of bifurcation anatomy and the resultant effect of different stenting techniques. Methods and Results: All three bifurcation angles were described according to the European Bifurcation Club definition: the A (proximal bifurcation angle), the B (distal bifurcation angle) and the C (main branch angle). Measurements were performed in 75 LM and 140 N-LM bifurcations. In LM bifurcations baseline mean values of C, A, and B were 151° ± 28°, 131° ± 32°, and 78 ± 28°, respectively. In bifurcations with 2 stents the B significantly decreased by a mean of 10° (P = 0.003) and A increased by 10° (P = 0.006). Crush stenting significantly decreased B (A - 14°; P = 0.020) and increased A (A + 21°; P = 0.005), particularly non-true bifurcations. In N-LM bifurcations mean values for C, A, and B were 156° ± 19°, 144° ± 22°, and 60° ± 20°, respectively. Similar to LM bifurcations, the B became narrower mainly at the expense of the A, which became wider. In both types of bifurcations the greatest variation in A and B was found following 2-stent techniques performed in T-shaped (≥70°) bifurcations. Conclusions: In both LM and N-LM bifurcations we found a significant difference in A and B pre- and post-PCI. This difference was driven by the 2-stent technique and was most evident with a baseline bifurcation angle ≥70°. The Crush technique caused the largest angle variation post-procedure, particularly in non-true LM bifurcations.