Evolution of ECG after refractory out-of-hospital cardiac arrest
D Kollin, Š Havranek, J Neuhofer, K Morev, P Kavalkova, M Vesela, D Rob, M Dusik, J Pudil, J BelohlavekAbstract
Introduction
The electrocardiographic (ECG) pattern evolves after out-of-hospital cardiac arrest (OHCA). To date, ECG dynamics in patients after prolonged and refractory OHCA have not been described. The aim of this analysis was to characterize the early evolution of ECG changes in patients with refractory OHCA included in the Prague OHCA study.
Methods
We analyzed the temporal evolution of available standard 12-lead ECG recordings in patients admitted after refractory OHCA. We evaluated changes in conduction intervals, QRS morphology, ST-segment deviations, T-wave dynamics, and their relationship to cardiac recovery and 30-day mortality. Patients with pacing, ventricular rhythm, lack of return of spontaneous circulation (ROSC), or early in-hospital death were excluded.
Results
A total of 117 patients were included (median age 55.8 years [IQR, 47–64]; 80% male). 58 (50 %) of patients had acute coronary syndrome (ACS). The median (IQR) number of ECGs per patient was 6 (3; 14). A dynamic of conduction intervals is shown in the Table/Figure 1. Trend toward PR interval shortening (p <0.01) and QRS narrowing (p <0.001) was observed. QTc was significantly prolonged to above 480 ms (p < 0.001). When compared to survivors, patients who died within 30 days showed significantly greater QTc prolongation between 4–8 and 8-12 hours after arrest (for interval 4-8 hours - 513,9 ms ± 38,1 vs. 498,1 ms ± 44,8; p <0.01, for interval 8-12 hours - 517,9 ms ± 48,1 vs. 499,9 ms ± 44,7; p <0.01). On the initial ECG, left bundle branch block (LBBB) was present in 15 patients (12%), and right bundle branch block (RBBB) in 23 patients (20%). Pathological Q waves were present or developed in 48 patients (41 %), predominantly among those with ACS (56 %). ST-segment elevation (excluding patients with bundle branch block) was found in 28 (27.5 %) of patients, of whom 22 (78.5%) had ACS. During follow-up, ST-segment normalization occurred in 65 % of cases. T-wave inversion developed in 60 % of patients. The sensitivity and specificity of ST elevation in predicting ACS were 42,3% and 88,2%, respectively.
Conclusion
In patients after refractory OHCA, significant QTc prolongation is present, with greater prolongation between 4–12 hours post-arrest in those who died within 30 days. PR and QRS intervals tend to shorten over time. Common ECG findings include transient ST-segment elevations in the early phase, predominantly in ACS cases. T-wave inversion develops in the majority of patients.