title: Impact of collateral flow on myocardial reperfusion and infarct size in patients undergoing primary angioplasty for acute myocardial infarction.
abstract: BACKGROUND
  The prognostic impact of baseline collateral flow of the infarct-related artery (IRA) in patients undergoing primary percutaneous coronary intervention (PCI) remains controversial. We sought to examine the impact of baseline collateral flow to the IRA on reperfusion success, infarct size, and clinical outcomes in patients undergoing primary PCI for acute myocardial infarction (AMI).
  
  
  RESULTS
  Acute procedural, 30-day, and 6-month clinical outcomes were assessed after primary PCI among patients enrolled in the EMERALD trial (n = 501 with AMI within 6 hours of onset). Patients with collateral flow to the IRA (Rentrop grade 2 or 3) more commonly had prior stable angina, less commonly had failed thrombolysis and left anterior descending artery occlusion, and presented with less ST-segment elevation. Myocardial reperfusion assessed by ST-segment recovery and myocardial blush was similar in patients with and without baseline collateral flow to the IRA. Infarct size (assessed by technetium Tc 99m sestamibi) was similar among patients with and without baseline collateral flow in anterior infarction (mean 28.5% vs 31.2%, respectively; P = .59) and nonanterior infarction (12.5% vs 12.1%, respectively; P = .81). There were no differences in the rates of major adverse cardiac events at 30 days or 6 months according to baseline IRA collateral flow.
  
  
  CONCLUSIONS
  Among patients undergoing primary PCI for AMI within 6 hours of symptom onset, we found no significant relationship between baseline collateral flow and either reperfusion success, infarct size, or subsequent clinical outcomes.
authors.affiliation: Mayo Clinic, Rochester, MN, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Sorajja
authors.forename: Bernard J
authors.initials: BJ
authors.lastname: Gersh
authors.forename: Roxana
authors.initials: R
authors.lastname: Mehran
authors.forename: Alexandra J
authors.initials: AJ
authors.lastname: Lansky
authors.forename: Mitchell W
authors.initials: MW
authors.lastname: Krucoff
authors.forename: John
authors.initials: J
authors.lastname: Webb
authors.forename: David A
authors.initials: DA
authors.lastname: Cox
authors.forename: Bruce R
authors.initials: BR
authors.lastname: Brodie
authors.forename: Gregg W
authors.initials: GW
authors.lastname: Stone
mesh_terms: D000368:Aged; D015906:Angioplasty, Balloon, Coronary; D003097:Collateral Circulation / Q000502:physiology*; D003326:Coronary Circulation / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000628:therapy*; D011379:Prognosis; D011877:Radionuclide Imaging; D016896:Treatment Outcome