title: Does rich coronary collateral circulation distal to chronically occluded left anterior descending artery compete with graft flow?
abstract: OBJECTIVE
  In coronary artery bypass grafting (CABG), graft flow distal to a mild stenosis can compete with relatively preserved native flow through the stenosis and the competition can result in graft stenosis. In chronic total occlusion (CTO), coronary collateral circulation, which is essential to maintain myocardial viability distal to CTO, varies in extent among patients and the extent can be scored by Rentrop grade in coronary angiography. We investigated whether rich collateral circulation distal to CTO competes with distally anastomosed graft flow in association with Rentrop grade.
  
  
  METHODS
  Of 666 patients who underwent CABG from January 2001 to December 2012, 70 patients whose left internal thoracic artery (ITA) was grafted distal to CTO in the left anterior descending artery (LAD) were divided into three groups: Poor collaterals (Rentrop grades 0 and 1, Group P, n = 22), Moderate collaterals (grade 2, Group M, n = 23) and Rich collaterals (grade 3, Group R, n = 25). The intraoperative measurements of mean graft flow (MGF) and pulsatility index (PI) of left ITA grafts, early graft patency and long-term clinical outcomes were compared.
  
  
  RESULTS
  The MGF and PI of left ITA grafts differed significantly among the three groups (P = 0.025 and P = 0.046, respectively). Lower Rentrop grade was associated with preferable results of higher MGF and lower PI. The graft flow pattern in Group P showed a significantly higher MGF (P = 0.020) and lower PI (P = 0.041) than those in Group R. All early postoperative coronary angiograms showed patent left ITA grafts. Serial echocardiographic evaluations, survival rates and cardiac event-free rates were comparable with the follow-up of 5.00 ± 3.11 years.
  
  
  CONCLUSIONS
  Rich collateral circulation distal to CTO in LADs can potentially compete with graft flow, although the competition seems not to affect clinical outcomes probably due to the regression of collaterals surmounted by the graft flow. Rentrop grade is shown to certainly reflect the degree of collateral haemodynamic circulation distal to CTO and especially important to evaluate intraoperative graft flow appropriately, considering the possible phenomenon of graft flow competition.
authors: Department of Cardiovascular Surgery, Osaka City University Graduate School of Medicine, Abeno-ku, Osaka, Japan.
authors: Daisuke
authors: D
authors: Kaku
authors: Atsushi
authors: A
authors: Nakahira
authors: Hidekazu
authors: H
authors: Hirai
authors: Yasuyuki
authors: Y
authors: Sasaki
authors: Mitsuharu
authors: M
authors: Hosono
authors: Yasuyuki
authors: Y
authors: Bito
authors: Yasuo
authors: Y
authors: Suehiro
authors: Shigefumi
authors: S
authors: Suehiro
mesh_terms: D000368:Aged; D001783:Blood Flow Velocity; D003097:Collateral Circulation; D017023:Coronary Angiography; D001026:Coronary Artery Bypass / Q000009:adverse effects; D003326:Coronary Circulation; D054059:Coronary Occlusion / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D003331:Coronary Vessels / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D063177:Pulse Wave Analysis; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013997:Time Factors; D016896:Treatment Outcome; D014654:Vascular Patency
keywords: Collateral circulation; Coronary artery bypass grafting; Coronary circulation; Coronary occlusion; Pulse wave analysis
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