The Left Main Bifurcation Angle and Changes Throughout the Cardiac Cycle: Quantitative Implications for Left Main Bifurcation Stenting and Stents.

OBJECTIVE: The objective of this study was to quantify the left main (LM) bifurcation angles and their changes throughout the cardiac cycle.

BACKGROUND: LM stenting is an accepted alternative to coronary artery bypass grafting. However, the LM bifurcation has great anatomic variability. Three-dimensional angles and their cyclic changes are important for coronary stenting.

METHODS: Patients undergoing coronary computed tomography angiography (CCTA) for chest pain were scanned and analyzed in three-dimensional views for left main-left anterior descending (LM-LAD), left main-left circumflex (LM-LCX), and left anterior descending-left circumflex (LAD-LCX) angles and their cyclic changes. Calculations and assessment of angles, angular variability, and how these angles change throughout the cardiac cycle were analyzed.

RESULTS: Forty-four patient scans were analyzed. The median end-diastolic LM-LCX angle was 130° and the LAD-LCX was 74°. Median end-systolic angle for the LM-LCX was 133°, and LAD-LCX was 69°. Large differences were found across all three absolute angles (LM-LCX, LAD-LCX, LM-LAD). Marked variability also occurred in how these angles changed throughout the cardiac cycle.

CONCLUSIONS: LM bifurcation geometry in patients shows marked absolute angle variability, as does diastolic-systolic angle movement. LM bifurcation stents should accommodate wide interpatient bifurcation angles at rest for both the LM-LAD and LM-LCX angles.