title: Long-term patency of internal mammary artery bypass grafts: relationship with preoperative severity of the native coronary artery stenosis.
abstract: BACKGROUND
  Internal mammary artery conduits (IMA) have an excellent long-term patency rate. Nevertheless, graft closure does occur and significantly limits future revascularization options. We sought to investigate the relationship between the long-term patency of IMA with clinical and angiographic parameters. Particularly, the preoperative degree of stenosis of the relevant bypassed coronary vessel was assessed to analyze the importance of chronic competitive flow on the arterial graft closure rate.
  
  
  RESULTS
  Consecutive patients in whom occlusion of at least 1 IMA had been documented at angiography (OCC group) were compared with a group of patients with patent IMA grafts (PAT group). The degree of stenosis in the native coronary artery on which the IMA was placed was analyzed by off-line quantitative coronary angiography. Multivariate stepwise logistic regression was used to identify independent clinical and angiographic predictors of occlusion. The OCC group comprised 96 patients (67+/-10 years) with 103 native bypassed arteries analyzed. The PAT group comprised 127 patients (69+/-8 years) with 170 native bypassed arteries analyzed. Both groups were similar except for gender (42% versus 32% female; P=0.04), height (166+/-8 versus 169+/-8 cm; P=0.006), minimum lumen diameter (0.76+/-0.7 versus 0.51+/-0.5; P=0.001), and diameter stenosis of the native artery (73+/-25% versus 84+/-16%; P<0.0001) in OCC versus PAT, respectively. In the multivariate analysis, only percent diameter stenosis was an independent and statistically significant predictor for graft patency. Among IMA placed on coronary arteries with a diameter of stenosis <50% (n=28), the occlusion rate was very high (79%).
  
  
  CONCLUSIONS
  The degree of stenosis in the native vessel is a major predictor of internal mammary artery bypass graft patency. The association between nonsignificant stenosis of the native artery and high occlusion rate of the arterial bypass conduit raises concerns about the use of IMA in the treatment of native vessels with only mild or moderate stenosis.
authors.affiliation: Cardiovascular Center, OLV Ziekenhuis, Aalst, Belgium.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Berger
authors.forename: Philip A
authors.initials: PA
authors.lastname: MacCarthy
authors.forename: Uwe
authors.initials: U
authors.lastname: Siebert
authors.forename: Stéphane
authors.initials: S
authors.lastname: Carlier
authors.forename: William
authors.initials: W
authors.lastname: Wijns
authors.forename: Guy
authors.initials: G
authors.lastname: Heyndrickx
authors.forename: Jozef
authors.initials: J
authors.lastname: Bartunek
authors.forename: Hugo
authors.initials: H
authors.lastname: Vanermen
authors.forename: Bernard
authors.initials: B
authors.lastname: De Bruyne
mesh_terms: D000368:Aged; D001827:Body Height; D015897:Comorbidity; D017023:Coronary Angiography; D023903:Coronary Restenosis / Q000000981:diagnostic imaging / Q000453:epidemiology*; D023921:Coronary Stenosis / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D005260:Female; D006083:Graft Occlusion, Vascular / Q000000981:diagnostic imaging / Q000453:epidemiology*; D006801:Humans; D007387:Internal Mammary-Coronary Artery Anastomosis / Q000706:statistics & numerical data*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D012737:Sex Factors; D013997:Time Factors; D014654:Vascular Patency