title: Is there a referral bias against catheterization of patients with reduced left ventricular ejection fraction? Influence of ejection fraction and inducible ischemia on post-single-photon emission computed tomography management of patients without a history of coronary artery disease.
abstract: OBJECTIVE
  The objective of this work was to define the relationship between left ventricular perfusion/ function measures and referral rates to catheterization and revascularization early after stress gated myocardial perfusion single-photon emission computed tomography (MPS).
  
  
  BACKGROUND
  Although revascularization yields the greatest survival benefit in patients with low ejection fraction (EF) and extensive coronary artery disease, referral patterns to catheterization and revascularization after noninvasive testing are not well defined.
  
  
  METHODS
  We identified 3,369 patients without previous myocardial infarction or revascularization who underwent exercise or adenosine stress MPS and who were followed-up (97% complete) for occurrence of early (<60 days) post-single-photon emission computed tomography (SPECT) revascularization. Multivariable logistic regression modeling was used to determine the association of various patient characteristics and test results with performance of catheterization and revascularization as separate end points.
  
  
  RESULTS
  In the first 60 days after stress MPS, 445 catheterizations (13.2%) and 254 revascularizations (7.5%) occurred, including 140 coronary artery bypass graft surgeries (4.1%) and 114 percutaneous coronary interventions (3.4%). Both post-stress gated EF and percent of the myocardium ischemic by stress MPS were independent predictors of revascularization. Logistic regression revealed that the likelihood of catheterization increased with both increasing ischemia and decreasing EF (c-index = 0.94, chi-square = 590). Predicted referral rates to catheterization increased with decreasing EF except in patients with severe ischemia (>15% of myocardium), where rates decreased with decreasing EF. Similar modeling of revascularization (c-index = 0.94, chi-square = 329) revealed that the likelihood of revascularization increased with increasing ischemia but, in general, decreased with decreasing EF.
  
  
  CONCLUSIONS
  Although post-SPECT referral to both catheterization and revascularization is driven by ischemia, EF has the opposite effect on these two outcomes. Further studies evaluating the appropriateness of these referral patterns are warranted.
authors.affiliation: Cardiovascular Division, Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California, USA.
authors.forename: Rory
authors.initials: R
authors.lastname: Hachamovitch
authors.forename: Sean W
authors.initials: SW
authors.lastname: Hayes
authors.forename: John D
authors.initials: JD
authors.lastname: Friedman
authors.forename: Ishac
authors.initials: I
authors.lastname: Cohen
authors.forename: Xingping
authors.initials: X
authors.lastname: Kang
authors.forename: Guido
authors.initials: G
authors.lastname: Germano
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Berman
mesh_terms: D000241:Adenosine; D000368:Aged; D015906:Angioplasty, Balloon, Coronary / Q000706:statistics & numerical data; D002140:California; D005080:Exercise Test; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging* / Q000601:surgery*; D009204:Myocardial Revascularization / Q000706:statistics & numerical data*; D017063:Outcome Assessment, Health Care; D018579:Patient Selection; D012017:Referral and Consultation / Q000706:statistics & numerical data*; D013794:Thallium Radioisotopes; D015899:Tomography, Emission-Computed, Single-Photon / Q000706:statistics & numerical data; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging*
chemical_list: D013794:Thallium Radioisotopes; D000241:Adenosine