A novel ECG-biomarker for cardiac arrest during hypothermia

Abstract

Background Treatment of arrhythmias evoked by accidental or therapeutic hypothermia and rewarming remains challenging. We aim to find an ECG-biomarker that can predict ventricular arrhythmias at temperatures occurring in therapeutic and accidental hypothermia. Main body Evaluation of ECG-data from accidental and therapeutic hypothermia patients and experimental data on ECG and ventricular fibrillation (VF) threshold in hypothermic New Zealand White Rabbits. VF threshold was measured in rabbit hearts cooled to moderate (31 °C) and severe (17 °C) hypothermia. QRS-interval divided by corrected QT-interval (QTc) was calculated at same temperatures. Clinical QRS/QTc data were obtained after a systematic literature review. Rabbit QRS/QTc values correlated with risk for VF (correlation coefficient: 0.97). Human QRS/QTc values from hypothermic patients, showed similar correlation with risk for ventricular fibrillation in the experimental data (correlation coefficient: 1.00). Conclusions These calculations indicate that QRS/QTc has potential as novel biomarker for predicting risk of hypothermia-induced cardiac arrest. Our findings apply both to victims of accidental hypothermia and to patients undergoing therapeutic hypothermia during surgery or after e.g. cardiac arrest.

Resistance to ventricular fibrillation predicted by the QRS/QTc - ratio in an intact rat model of hypothermia/rewarming

“…This mismatch was prominent at 31 °C and was associated with a doubled risk for inducing ventricular brillation (VF) [7]. Further temperature reduction, towards 20 °C and below, appears anti-arrhythmic in these experiments [4,6,7].…”

“…Background pathophysiologic mechanisms for hypothermia-induced VF and cardiac arrest in patients has been largely unknown. However, recent efforts with translational research into this topic have given possible groundbreaking results [6]. In rabbit, both increased ventricular divergence [9] and heterogenic effect of hypothermia on transmural and longitudinal conduction [7] has been documented at 30 °C, with increased risk for developing VF.…”

“…Further, we found that a novel ECG-marker (QRS/QTc) could predict risk for VF in hypothermic rabbit hearts and advocated that this marker also show potential when assessing hypothermic patients [6].…”

“…In a series of recent preclinical experiments, we have investigated the pathophysiology of hypothermiainduced VF and cardiac arrest (HCA) [4,6,7]. Our ndings show that moderate hypothermia (32 − 28 °C)…”

“…is pro-arrhythmic [4,6,7]. An underlying depolarisation-repolarisation mismatch is apparent in rabbit hearts, a species with similar cardiac electrophysiology to humans.…”