Repolarization and ventricular arrhythmia during targeted temperature management post cardiac arrest

Area of Science:

• Cardiology
• Critical Care Medicine
• Electrophysiology

Background:

• Targeted temperature management (TTM) after out-of-hospital cardiac arrest (OHCA) is standard care.
• TTM's effect on QT-interval and arrhythmia risk at different temperatures requires further investigation.

Purpose of the Study:

• To evaluate QT, QT-peak (QTp), and T-peak to T-end (TpTe) intervals as markers of ventricular arrhythmia.
• To assess the impact of different TTM temperatures (33°C vs. 36°C) on these ECG parameters.

Main Methods:

• ECG substudy of the TTM-trial involving 680 patients.
• Serial ECG recordings with heart rate correction using Bazett's and Fridericia's formulas.
• Correlation of ECG intervals with ventricular arrhythmia (VT/VF) during the first three days post-arrest.

Main Results:

• QT and QTp intervals prolonged more at 33°C compared to 36°C.
• QTc intervals showed association with arrhythmia, but not after adjusting for arrest characteristics.
• Heart rate-corrected TpTe intervals were robustly associated with increased ventricular arrhythmia risk.

Conclusions:

• TTM prolongs the QT-interval via QTp prolongation, without increasing arrhythmia risk.
• TpTe intervals are not significantly affected by core temperature.
• Heart rate-corrected TpTe intervals are reliable predictors of ventricular arrhythmia risk post-cardiac arrest.