Extreme QT prolongation during therapeutic hypothermia after cardiac arrest due to long QT syndrome

Am J Emerg Med. 2012 May;30(4):638.e5-8. doi: 10.1016/j.ajem.2011.02.019. Epub 2011 Apr 2.


During therapeutic hypothermia, QT interval is prolonged. In patients with congenital long QT syndrome (LQTs), a longer QT interval was associated with significantly increased risk of cardiac arrest (CA). Therefore, therapeutic hypothermia may have proarrhythmic effects in survivors of CA due to congenital LQTs. A 27-year-old man was resuscitated from CA due to congenital LQTs type 3 and Brugada syndrome. Torsade de pointes (TdP) recurred spontaneously on admission (body temperature, 36.9°C). During mild hypothermia therapy, QTc increased from 499 (36.9°C) to 667 milliseconds (33.8°C), although TdP was not induced. A 13-year-old boy with congenital LQTs type 1 underwent therapeutic hypothermia after resuscitation. Short-acting β-blocker was administered intravenously during this treatment. The QTc increased from 534 (36.4°C) to 626 milliseconds (34.3°C). However, TdP did not recur during mild hypothermia therapy. In both patients, electrolyte abnormalities were checked frequently and corrected immediately. QT prolongation remained a couple of days after completion of rewarming. The withdrawal of sedative drugs and extubation were not pursued before QT shortening reached to a plateau. Both patients were fully recovered from neurologic damage. During therapeutic hypothermia, QT interval was extremely prolonged, although TdP did not recur in 2 patients with congenital LQTs. Therapeutic hypothermia may be beneficial for comatose survivors of CA due to LQTs.

Publication types

  • Case Reports

MeSH terms

  • Adolescent
  • Adult
  • Electrocardiography
  • Heart / physiopathology
  • Heart Arrest / etiology
  • Heart Arrest / physiopathology
  • Heart Arrest / therapy*
  • Humans
  • Hypothermia, Induced / adverse effects*
  • Long QT Syndrome / complications*
  • Long QT Syndrome / etiology
  • Long QT Syndrome / physiopathology
  • Male