title: Changes in myocardial ischemic burden following percutaneous coronary intervention of chronic total occlusions.
abstract: OBJECTIVE
  We assessed the potential for percutaneous coronary intervention (PCI) of a chronic total occlusion (CTO) to decrease myocardial ischemia and established objective criteria to predict post-procedure improvement.
  
  
  BACKGROUND
  Optimal treatment for CTO of coronary arteries is controversial, and selection criteria for PCI of CTO are subjective.
  
  
  METHODS
  All patients undergoing CTO PCI at a single center between 2002 and 2007 were included if myocardial perfusion imaging (MPI) was performed within 12 ± 3 months before and a follow-up study within 12 ± 3 months after PCI. Average summed difference scores were calculated and converted to percent ischemic myocardium to classify patients as having normal/minimal, mild, moderate, or severe ischemia. A significant improvement in ischemia following PCI was classified as an absolute ≥5% decrease in ischemic myocardium. Receiver operating characteristic (ROC) curves were used to identify ischemic thresholds predictive of decreased and increased ischemic burden on follow-up MPI.
  
  
  RESULTS
  In 301 patients, average baseline ischemic burden was 13.1% ± 11.9% and decreased to 6.9% ± 6.5% (P < 0.001) during follow-up. Overall, 53.5% of patients met criteria for improvement following PCI. These patients were more likely to be male, without diabetes, with CTO in the left anterior descending artery, and classified as having high ischemic burden at baseline. ROC analysis identified a baseline 12.5% ischemic burden as optimal in identifying those most likely to have a significantly decreased ischemic burden post-PCI. Those with a baseline ischemic burden less than 6.25% were more likely to have an increased ischemic burden post-PCI.
  
  
  CONCLUSIONS
  Ischemic burden is reduced following CTO PCI, and the decrease is greater at high ischemic burden. A threshold of 12.5% ischemic burden is suggested as a criterion for performing PCI in the setting of CTO.
authors.affiliation: Mid America Heart and Vascular Institute, St. Luke's Hospital, Kansas City, Missouri, USA. dsafley@cc-pc.com
authors.forename: David M
authors.initials: DM
authors.lastname: Safley
authors.forename: Sindhu
authors.initials: S
authors.lastname: Koshy
authors.forename: J Aaron
authors.initials: JA
authors.lastname: Grantham
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Bybee
authors.forename: John A
authors.initials: JA
authors.lastname: House
authors.forename: Kevin F
authors.initials: KF
authors.lastname: Kennedy
authors.forename: Barry D
authors.initials: BD
authors.lastname: Rutherford
mesh_terms: D000368:Aged; D015906:Angioplasty, Balloon, Coronary / Q000009:adverse effects / Q000401:mortality; D002908:Chronic Disease; D017023:Coronary Angiography; D003326:Coronary Circulation; D054059:Coronary Occlusion / Q000150:complications / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D008923:Missouri; D017202:Myocardial Ischemia / Q000175:diagnosis / Q000209:etiology / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*; D055414:Myocardial Perfusion Imaging / Q000379:methods; D018579:Patient Selection; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D012372:ROC Curve; D012042:Registries; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon; D016896:Treatment Outcome