Ventricular ectopic burden in comatose survivors of out-of-hospital cardiac arrest treated with targeted temperature management at 33°C and 36°C

Purpose: Life threatening arrhythmias are increasingly frequent with lower body temperature. While targeted temperature management (TTM) with mild hypothermia following out-of-hospital cardiac arrest (OHCA) is generally considered safe and has been suggested as a potential antiarrhythmic add-on therapy, it is unknown whether the level of TTM affects the burden of ventricular ectopic activity. We sought to assess the ventricular ectopic burden between patients treated with TTM at 33°C or 36°C for 24h.

Methods: Continuous 12-lead digital Holter electrocardiograms performed during the intervention were analyzed blinded to treatment allocation in 115 comatose OHCA-survivors from a single center of the TTM-trial. The main study showed no difference with regards to mortality.

Results: Fifty-eight patients were randomized to 33°C and 57 to 36°C. Cardiac arrest characteristics were similar between the groups. The number of isolated ventricular ectopic beats (VEB) per hour was similar at the beginning of the maintenance phase of TTM and decreased over time in both groups (both ptime<0.001). The reduction in VEB per hour was significantly affected by target temperature (pinteraction<0.0001), with fewer VEB in the 36°C-group. The total number of isolated, couplets and number of runs of VEB per hour showed similar results, with less ventricular ectopic activity in the 36°C-group (pinteraction<0.0001). Increasing numbers of pre-hospital defibrillations (log2) were associated with a 46% increase in ventricular ectopic activity (p<0.01), adjusted for potential confounders.

Conclusions: Ventricular ectopic activity was reduced in comatose OHCA-survivors treated with TTM at 36°C compared to 33°C. Higher numbers of pre-hospital defibrillations were associated with higher incidence of ventricular ectopic activity.