title: A novel clinically relevant segmentation method and corresponding maximal ischemia score to risk-stratify patients undergoing myocardial perfusion scintigraphy.
abstract: BACKGROUND
  Myocardial perfusion scintigraphy (MPS) represents a key prognostic tool, but its predictive yield is far from perfect. We developed a novel clinically relevant segmentation method and a corresponding maximal ischemia score (MIS) in order to risk-stratify patients undergoing MPS.
  
  
  METHODS
  Patients referred for MPS were identified, excluding those with evidence of myocardial necrosis or prior revascularization. A seven-region segmentation approach was adopted for left ventricular myocardium, with a corresponding MIS distinguishing five groups (no, minimal, mild, moderate, or severe ischemia). The association between MIS and clinical events was assessed at 1 year and at long-term follow-up.
  
  
  RESULTS
  A total of 8,714 patients were included, with a clinical follow-up of 31 ± 20 months. Unadjusted analyses showed that subjects with a higher MIS were significantly different for several baseline and test data, being older, having lower ejection fraction, and achieving lower workloads (P < .05 for all). Adverse outcomes were also more frequent in patients with higher levels of ischemia, including cardiac death, myocardial infarction (MI), and their composites (P < .05 for all). Differences in adverse events remained significant even after extensive multivariable adjustment (hazard ratio for each MIS increment = 1.57 [1.29-1.90], P < .001 for cardiac death; 1.19 [1.04-1.36], P = .013 for MI; 1.23 [1.09-1.39], P = .001 for cardiac death/MI).
  
  
  CONCLUSIONS
  Our novel segmentation method and corresponding MIS efficiently yield satisfactory prognostic information.
authors.affiliation: Service of Nuclear Cardiology, Madonna della Fiducia Clinic, Via Cesare Correnti 6, 00179, Rome, Italy, francesco.nudi@etisan.eu.
authors.forename: Francesco
authors.initials: F
authors.lastname: Nudi
authors.forename: Annamaria
authors.initials: A
authors.lastname: Pinto
authors.forename: Enrica
authors.initials: E
authors.lastname: Procaccini
authors.forename: Giandomenico
authors.initials: G
authors.lastname: Neri
authors.forename: Maurizio
authors.initials: M
authors.lastname: Vetere
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Tomai
authors.forename: Achille
authors.initials: A
authors.lastname: Gaspardone
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Biondi-Zoccai
authors.forename: Orazio
authors.initials: O
authors.lastname: Schillaci
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging* / Q000401:mortality; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D011379:Prognosis; D012189:Retrospective Studies; D012306:Risk