Open Heart. 2026 Sep 22;13(2):e004173. doi: 10.1136/openhrt-2026-004173.
ABSTRACT
BACKGROUND: Out-of-hospital cardiac arrest (OHCA) treatment often requires multiple defibrillatory shocks due to failed defibrillation or refibrillation. The complete nature of refractory ventricular fibrillation (VF) is unknown, as many studies do not consider shocks delivered by lay rescuers prior to the arrival of basic life support (BLS)/advanced life support (ALS) when quantifying refractory VF. ERC guidelines define refractory VF as continuous VF after three consecutive shocks, not differentiating between patients who refibrillate and those with shock-resistant VF (three consecutive failed shocks) which may contribute to this variation in reported incidence. There are some differences in treatment recommendations for patients who refibrillate and those with shock-resistant VF. Therefore, understanding the number of shocks delivered by lay-rescuers with public access defibrillators (PADs) and the patient's response to them prior to BLS/ALS arrival may inform treatment strategies.
METHODS: ECG data collected retrospectively from OHCAs treated by lay-rescuers using PADs were analysed. Cardiac rhythm, shock success, refibrillation, time to refibrillation and presence of shock-resistant VF (three consecutive failed shocks) were determined by two investigators.
RESULTS: Data were available for 1459 patients receiving at least one shock. Refibrillation occurred in 498 (34.1%) patients. The median number of refibrillations per patient was 1 (IQR 1, 2). Median time to refibrillation was 29.8 s. Three consecutive shocks were observed in 231 of the 1459 (15.8%) patients, 11 patients (4.8% of 231 patients) had shock-resistant VF.
CONCLUSION: When treated by lay-rescuers with PADs, refibrillation occurrence is lower than that reported for patients treated by BLS/ALS. However, aligned with BLS/ALS studies, in lay-rescuer treated OHCA, refibrillation typically occurs within the first 30 s following a successful shock. Therefore, patients who refibrillate are typically in VF for an additional 1.5 min before receiving a subsequent shock for PADs with a 2 min cardiopulmonary resuscitation (CPR) cycle. This finding emphasises the need for investigation into optimal CPR duration for patients requiring multiple shocks.
PMID:42772919 | DOI:10.1136/openhrt-2026-004173