title: Intravascular ultrasound assessment of distal left main bifurcation disease: the importance of the polygon of confluence of the left main, left anterior descending, and left circumflex arteries.
abstract: BACKGROUND
  The polygon of confluence (POC) represents the zone of confluence of the distal left main (LM), ostial left anterior descending (LAD), and ostial left circumflex (LCX) arteries.
  
  
  METHODS
  We used intravascular ultrasound (IVUS) to assess the POC pre and post-drug-eluting stent implantation for unprotected distal LM disease. Four segments within 82 LM bifurcation lesions were defined by longitudinal IVUS reconstruction: (1) ostial LAD, (2) POC, and (3) distal LM (DLM)--from LAD-pullback, and (4) ostial LCX from LCX-pullback.
  
  
  RESULTS
  Preprocedural minimum lumen area (MLA) and poststenting minimum stent area (MSA) within the LM were mainly located within the POC (51 and 71%). On ROC analysis, a cut-off of the MLA within the POC of 6.1 mm(2) predicted significant LCX carinal stenosis (85% sensitivity, 52% specificity, AUC = 0.7, 95% CI = 0.57-0.78, P < 0.01). Poststenting MSA within the distal LM proximal to the carina (to include DLM and POC) positively correlated with the preprocedural MLA within the POC (r = 0.283, P = 0.02); it was significantly smaller in 48 lesions with a pre-PCI MLA within the POC < 6.1 mm(2) versus 25 lesions with a pre-PCI MLA ≥6.1 mm(2) (7.5 ± 2.1 mm(2) vs. 8.6 ± 2.0 mm(2), P = 0.04). Independent predictors for poststenting LCX carinal MLA also included preprocedural MLA within the POC (β = 0.240, 95% CI = 0.004-0.353, P = 0.04).
  
  
  CONCLUSIONS
  The MLA within the POC was a good surrogate reflecting the overall severity of LM bifurcation disease including ostial LCX stenosis pre-PCI and the ability to expand a stent within the distal LM as well as final ostial LCX lumen area post-PCI.
authors.affiliation: Department of Cardiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Soo-Jin
authors.initials: SJ
authors.lastname: Kang
authors.forename: Gary S
authors.initials: GS
authors.lastname: Mintz
authors.forename: Jun-Hyok
authors.initials: JH
authors.lastname: Oh
authors.forename: Duk-Woo
authors.initials: DW
authors.lastname: Park
authors.forename: Seung-Whan
authors.initials: SW
authors.lastname: Lee
authors.forename: Young-Hak
authors.initials: YH
authors.lastname: Kim
authors.forename: Cheol Whan
authors.initials: CW
authors.lastname: Lee
authors.forename: Seong-Wook
authors.initials: SW
authors.lastname: Park
authors.forename: Seung-Jung
authors.initials: SJ
authors.lastname: Park
mesh_terms: D017023:Coronary Angiography; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000628:therapy; D023921:Coronary Stenosis / Q000000981:diagnostic imaging* / Q000628:therapy; D003331:Coronary Vessels / Q000000981:diagnostic imaging*; D054855:Drug-Eluting Stents; D006801:Humans; D062645:Percutaneous Coronary Intervention / Q000009:adverse effects / Q000295:instrumentation; D058226:Plaque, Atherosclerotic; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D016896:Treatment Outcome; D018084:Ultrasonography, Interventional