3-Dimensional Bifurcation Angle Analysis in Patients With Left Main Disease. A Substudy of the SYNTAX Trial (SYNergy Between Percutaneous Coronary Intervention With TAXus and Cardiac Surgery)
Objectives: We explore the bifurcation angle (BA) parameters of the left main coronary artery (LM), the effect of percutaneous coronary intervention (PCI) on this angulation, and the impact of BA on clinical outcome. Background: The BA is emerging as a predictor of outcome after PCI of bifurcation lesions. Three-dimensional (3D) quantitative coronary angiography (QCA) overcomes the shortcomings of 2-dimensional analysis and provides reliable data. Methods: This is a substudy of the SYNTAX (SYNergy Between Percutaneous Coronary Intervention With TAXus and Cardiac Surgery) trial. The cineangiograms of the 354 patients who underwent PCI of their LM stem were analyzed with 3D QCA software (CardiOp-B, Paieon Medical, Ltd., Rosh Ha'ayin, Israel). The proximal BA (between LM and left circumflex [LCX]) and the distal BA (between left anterior descending and LCX) were computed in end-diastole and end-systole, both before and after PCI. The cumulative major adverse cardiac and cardiovascular event (MACCE) rates throughout the 12-month period after randomization were stratified across pre-PCI distal BA values and compared accordingly. Results: Complete analysis was feasible in 266 (75.1%) patients. Proximal and distal BA had mean pre-PCI end-diastolic values of 105.9 ± 21.7° and 95.6 ± 23.6°, respectively, and were inversely correlated (r = -0.75, p < 0.001). During systolic motion of the heart there was an enlargement of the proximal angle and a reduction of the distal angle (ΔBA -8.2° and 8.5°, respectively, p < 0.001 for both). The PCI resulted in a mean decrease in the distal BA (ΔBA 4.5°, p < 0.001). The MACCE rates did not differ across distal BA values; freedom from MACCE at 12 months was 82.8%, 85.4%, and 81.1% (p = 0.74) for diastolic values (first through third tertile). Conclusions: Left main BA analysis with 3D QCA is feasible. Both proximal and distal angles are affected by cardiac motion; PCI modifies the distal angle. There is no clear difference in event rates across pre-PCI distal BA values.