title: Therapeutic hypothermia-induced electrocardiographic changes and relations to in-hospital mortality.
abstract: BACKGROUND
  Therapeutic hypothermia improves survival for selected patients who remain comatose after cardiac arrest. Hypothermia triggers changes in electrocardiographic (ECG) parameters; however, the association of these changes to in-hospital mortality remains unclear.
  
  
  OBJECTIVE
  QT interval changes induced by therapeutic hypothermia are not associated with in-hospital mortality.
  
  
  METHODS
  We retrospectively compared precooling ECG parameters to ECG parameters during hypothermia on all consecutive patients with available information who received hypothermia at our academic medical center between December 2006 and July 2012 (N = 101; 24% women). Paired 2-sample t test was used to compare precooling vs cooling ECG parameters. In-hospital mortality related to ECG parameter changes was compared using the Pearson χ(2) test.
  
  
  RESULTS
  Therapeutic hypothermia resulted in increases in PR and QTc intervals and decreases in heart rate and QRS intervals (P for all <0.02). During hospitalization, 45 of the 101 patients died. Survivors vs nonsurvivors did not differ in heart rate change (P = 0.74), PR change (P = 0.57), QRS change (P = 0.09), or QTc change (P = 0.67). Comparing patients who had reduced QTc intervals with hypothermia to those who had prolonged QTc with hypothermia, 14 out of 30 died in the former group, whereas 31 out of 71 died in the latter group (46.7% vs 43.7%, odds ratio [OR]: 1.13, 95% CI: 0.48-2.66). Patients presenting with right bundle branch block (RBBB) had a higher risk of in-hospital death compared to those without RBBB (72.2% vs 38.6%, OR: 4.14, 95% CI: 1.35-12.73).
  
  
  CONCLUSIONS
  Therapeutic hypothermia prolonged QTc interval with no association to in-hospital mortality. Presence of RBBB on initial presentation was related to increased mortality.
authors: Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire; Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts.
authors: David H
authors: DH
authors: Lam
authors: Ravi
authors: R
authors: Dhingra
authors: Sheila M
authors: SM
authors: Conley
authors: Alan T
authors: AT
authors: Kono
mesh_terms: D000046:Academic Medical Centers; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002037:Bundle-Branch Block / Q000209:etiology / Q000401:mortality / Q000503:physiopathology; D016009:Chi-Square Distribution; D003128:Coma / Q000175:diagnosis / Q000209:etiology / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*; D004562:Electrocardiography; D005260:Female; D006323:Heart Arrest / Q000150:complications* / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology; D006339:Heart Rate; D017052:Hospital Mortality; D006801:Humans; D007036:Hypothermia, Induced / Q000009:adverse effects / Q000401:mortality*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009513:New Hampshire; D016017:Odds Ratio; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult