title: Prolonged QT interval in ST-elevation myocardial infarction and mortality: new prognostic scale with QT, Killip and age.
abstract: OBJECTIVE
  To analyze the relation between prolonged QT interval and mortality in patients with ST-elevation myocardial infarction and complementarity with Killip, Thrombolysis in Myocardial Infarction (TIMI) and Acute Physiology and Chronic Health Evaluation-II (APACHE-II) scales.
  
  
  METHODS
  A nested cohort case-control study was conducted in a Spanish hospital. The cohort consisted of patients with ST-elevation myocardial infarction admitted between 2008 and 2010 (n = 524). The cases were the patients who died (n = 38) and the controls (n = 81) were a random sample of those who survived (one of every six).
  
  
  RESULTS
  The corrected QT (QTc) interval of first ECG (prehospital-or-hospital admission) was prolonged in 18 of the 35 patients who died (51.4%) and in 12 of the controls (16.7%; P < 0.001). APACHE-II, TIMI and Killip scores were higher in the patients who had died (P < 0.001). Mortality with prolonged QTc (19.3%) was 20%, and 4.5% were with normal QTc (80.7%; P < 0.001).Logistic regression showed a relation between mortality with prolonged QTc and TIMI [odds ratio (OR) 3.57(1.16-10.97)]. A second model was constructed with APACHE-II and prolonged QTc [OR 6.47(1.77-23.59)]; receiver operating characteristic (ROC) curve area [0.92(0.87-0.97)], and individually, for APACHE-II was 0.88 (0.81-0.95). A new score was constructed: QTc (not prolonged: 0 points, prolonged: 7 points), age (<65 years: 0 points, 65-74 years: 6 points, ≥75 years: 9 points), Killip (I: 0 points, II-III: 4 points, IV: 17 points). ROC area: 0.88.
  
  
  CONCLUSIONS
  Hospital mortality was higher with prolonged QTc at prehospital-or-hospital admission, given equal Killip, TIMI and APACHE values. Discrimination of Killip, TIMI and APACHE values can be improved with prolonged QTc. Discrimination of a model including Killip, age and prolonged QTc is quite good. We have made a new simple prognostic scale with these variables.
authors.affiliation: aIntensive Care Unit bCoronary Care Unit, Hospital Carlos Haya, Malaga cCIBERESP, Preventive Medicine and Public Health, University of Jaen dIntensive Care Unit, Hospital Infanta Margarita, Cabra (Cordoba), Spain.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Rivera-Fernández
authors.forename: Maria Dolores
authors.initials: MD
authors.lastname: Arias-Verdú
authors.forename: Teresa
authors.initials: T
authors.lastname: García-Paredes
authors.forename: Miguel
authors.initials: M
authors.lastname: Delgado-Rodríguez
authors.forename: José Andrés
authors.initials: JA
authors.lastname: Arboleda-Sánchez
authors.forename: Eduardo
authors.initials: E
authors.lastname: Aguilar-Alonso
authors.forename: Guillermo
authors.initials: G
authors.lastname: Quesada-García
authors.forename: Antonio
authors.initials: A
authors.lastname: Vera-Almazán
mesh_terms: D018806:APACHE; D054058:Acute Coronary Syndrome / Q000150:complications / Q000175:diagnosis / Q000401:mortality; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D004562:Electrocardiography; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D008133:Long QT Syndrome / Q000150:complications* / Q000175:diagnosis / Q000401:mortality; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications* / Q000175:diagnosis / Q000401:mortality; D011379:Prognosis; D018570:Risk Assessment / Q000379:methods; D012720:Severity of Illness Index; D013030:Spain / Q000453:epidemiology