Absence of a J-wave may be predictive of worse outcomes during therapeutic hypothermia in post cardiac arrest patients

Background The presence of Osborn or J-waves during hypothermia may be associated with increased propensity of arrhythmias, However, J-waves may be a normal physiologic response to hypothermia, since the activity of many... [ view full abstract ]

Background
The presence of Osborn or J-waves during hypothermia may be associated with increased propensity of arrhythmias, However, J-waves may be a normal physiologic response to hypothermia, since the activity of many cardiac ion channels is altered by temperature.

Objective
We sought to investigate if the absence of J-waves during hypothermia was associated with clinical outcome among cardiac arrest survivors and accidental hypothermic patients.

Methods
Cardiac arrest survivors undergoing mild therapeutic hypothermia and accidental hypothermic patients were evaluated for the presence or absence of J-waves during hypothermia (28-33 °C) using standard 12-lead electrocardiograms (ECGs). ECGs were assessed blinded to clinical outcome and using standard criteria. Subjects were followed an average of 6-years. The primary outcome was total mortality. In-hospital ventricular tachycardia or ventricular fibrillation were secondary outcomes.



Results
J-waves were present in 9 of the 44 (20%) cardiac arrest survivors and in all 10 of the accidental hyopthermia patients. Cardiac arrest survivors without J-waves had a higher rate of death (56%) as compared to cardiac arrest survivors with J-waves (34%) or accidental hypothermic patients (30%). Differences were largely related to in-hospital death. Survival among the groups remained significant, when stratified by clinically important variables including the presence of left ventricular dysfunction, prolonged down-time and the initial rhyhm at the time of initial resucitation; Log-rank p=0.05. Rates of in-hospital ventricular tachycardia or ventricular fibrillation were similar among the three groups.

Conclusion
The absence of J-waves during therapeutic hypothermia is associated with increased risk of death among cardiac arrest survivors.