Abstract 136: QTc Prolongation During Therapeutic Hypothermia: Does It Deserve Attention?
Background: Therapeutic hypothermia (TH) has become a standard of care for management of patients following sudden cardiac arrest (SCA). Hypothermia is associated with prolongation of the QTc interval which could lead to other cardiac dysrhythmias. We describe the effects of induced hypothermia on QTc prolongation and associated arrhythmic events in patients undergoing TH following SCA.
Methods: We retrospectively studied patients undergoing TH for SCA from June 2006 to December 2009. Baseline characteristics and serial 12 lead electrocardiograms prior to, during and post TH were analyzed. Using Bazett's formula the QTc interval was determined. Any ventricular dysrhythmia occurring during TH was identified.
Results: We identified thirty one patients with sufficient data and included in the analysis. A significant prolongation of the QTc from the baseline precooling value (QTc1) of 473 msec to 532 msec during cooling phase (QTc2) was seen (p=0.007). The QTc reverted back to the baseline value once the body temperature reached more than 36°C (p=0.98). The mean QTc during cooling phase (QTc2) of the patients who survived (13 patients) was 522 ± 87 msec vs 541 ± 76 msec among those who did not survive (p=0.5). Torsades de pointes occurred in 2 patients during the cooling phase, which terminated spontaneously. Two patients had monomorphic nonsustained VT; one during the cooling and the other during the warming phase. These arrhythmic events did not contribute to any death.
Conclusions: TH results in a transient prolongation of the QTc interval. This transient QTc prolongation does not appear to result in excess mortality even though ventricular dysrhythmias may occur during the period of hypothermia.
- © 2010 by American Heart Association, Inc.