Importance of the distinction between recurrent and shock-resistant ventricular fibrillation: Call for a uniform definition of refractory VF

摘要

Sir, With great interest we read the article on double sequential defibrillation (DSD) for refractory ventricular fibrillation (VF) during out-of-hospital cardiac arrest (OHCA). The authors provide an extensive overview of the available evidence on DSD, a treatment strategy aimed to improve the outcome of patients with refractory VF. In this study, another important issue is highlighted that goes beyond the scope of DSD alone, i.e. the lack of a universal definition of a patient with refractory VF. In the guidelines, refractory VF refers to VF that persists despite shock delivery (i.e. shock-resistant VF). This is distinguished from recurrent VF, which is VF that re-appears after it has been terminated. Importantly, some studies on refractory VF include only patients with shock-resistant VF, whereas others include all patients that need multiple shocks, regardless of the type ofVF. Inthe latter, itis likely that patients with both recurrent and shock-resistant VF have been included. This was also the case in at least one of the two studies included in the meta-analysis by Delorenzo et al. However, the distinction between recurrent and shock-resistant VF seems important, as the type of VF impacts chances of shock success. Appreciating that outcome has been related to the number of shocks needed, distinction between these two VF-types may also have prognostic consequences.