title: Single-photon emission computed tomography myocardial perfusion imaging-assessed stress perfusion defect severity is associated with mortality independent of ethnicity in an Asian population.
abstract: BACKGROUND
  Ischemic heart disease is growing by epidemic proportions in Asia. Among patients in Western populations with similar myocardial perfusion imaging (MPI) ischemia severity, ethnicity is independently associated with mortality. We aimed to determine the differential prognostic value of MPI abnormality severity among three major Asian ethnic groups.
  
  
  METHODS
  From 16,921 consecutive patients, we used summed stress score to define increasing abnormal scan severity groups (minimal, mild, moderate, and severe) among Chinese, Indian, and Malay patients. We determined mortality from the national death registry. Using multivariable Cox regression models, we examined the association between ethnicity and mortality.
  
  
  RESULTS
  Chinese patients were older than Indians or Malays. Annual all-cause death rates increased with increasing abnormal scan severity in all three ethnicities. After adjustment, ethnicity was not associated with mortality. With Chinese as the reference group, adjusted hazard ratio and 95% CI for Malays and Indians were 1.29 (0.95-1.77) and 1.06 (0.74-1.50) in the minimally abnormal scan group, and 1.20 (0.75-1.91) and 0.82 (0.47-1.45) in the severely abnormal scan group, respectively.
  
  
  CONCLUSIONS
  Mortality risk is related to the severity of scan abnormality and is independent of ethnicity in Asians. Our findings emphasize the continued utility of MPI in guiding risk stratification in Asia.
authors.affiliation: Department of Cardiology, National Heart Centre Singapore, Singapore, Singapore, chin.chee.tang@nhcs.com.sg.
authors.forename: Chee Tang
authors.initials: CT
authors.lastname: Chin
authors.forename: Fei
authors.initials: F
authors.lastname: Gao
authors.forename: Felix Y J
authors.initials: FY
authors.lastname: Keng
authors.forename: Bimal R
authors.initials: BR
authors.lastname: Shah
authors.forename: Angela S
authors.initials: AS
authors.lastname: Koh
authors.forename: Ru San
authors.initials: RS
authors.lastname: Tan
authors.forename: Terrance S J
authors.initials: TS
authors.lastname: Chua
mesh_terms: D017677:Age Distribution; D044466:Asian People / Q000706:statistics & numerical data*; D015897:Comorbidity; D003324:Coronary Artery Disease / Q000208:ethnology* / Q000401:mortality*; D016757:Death, Sudden, Cardiac; D005080:Exercise Test / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D055414:Myocardial Perfusion Imaging / Q000706:statistics & numerical data*; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D017678:Sex Distribution; D012846:Singapore / Q000208:ethnology; D015996:Survival Rate; D015899:Tomography, Emission-Computed, Single-Photon / Q000706:statistics & numerical data*