Remodeling of the 12-lead electrocardiogram in immediate survivors of sudden cardiac arrest

Background: The ECG is a critical diagnostic tool for the management of immediate sudden cardiac arrest (SCA) survivors, but can be altered as a consequence of the SCA event. A limited number of studies report that electrical remodeling post SCA is due to prolonged myocardial repolarization, but a better understanding of this phenomenon is needed. Aim: To identify specific ECG abnormalities that follow SCA in immediate survivors. Methods: SCA survivors with a pre-arrest ECG and an ECG obtained within 48 h post-SCA were prospectively collected in the Oregon Sudden Unexpected Death Study (Portland metro region) from 2002–2015. Ventricular depolarization and repolarization measurements were compared between pre-arrest and post-arrest ECGs using paired t-tests and assessed for association with survival using unpaired t-tests and Pearson's chi-square tests. Results: A pre-arrest ECG and post-arrest ECG were available for 297 SCA cases (67.8 ± 13.4 years; 65.3% male). From the pre- to post-arrest setting, there was a significant mean increase in QRS (21 ms, p < 0.001) and QTc (35 ms, p < 0.001) in each SCA case, while there was no significant change in the JTc (4 ms, p = 0.361). Post-arrest QRS duration was significantly shorter in cases who survived to hospital discharge compared with those who did not survive (mean QRSD 115 ± 29 ms vs 127 ± 34 ms; p = 0.006). Conclusions: Contrary to expectations, electrical remodeling of the ECG due to SCA occurs due to prolongation of ventricular depolarization (QRSD), and not repolarization (JTc). Prolonged QRSD may also assist with prognostication and warrants further evaluation.