Left sided Wall Stress Causing Arrhythmia | 203 INTRODUCTION Idiopathic ventricular fibrillation (IVF) is diagnosed in patients with ventricular fibrillation of unknown origin that remains unidentified after extensive diagnostic testing.1,2 The diagnosis IVF depends on the absence of a substrate for VF by exclusion of both structural cardiac diseases and primary arrhythmia syndromes. In the follow-up of these patients, a continuing search for previously unknown pro-arrhythmic factors is driven by the evolution of medical knowledge and diagnostic techniques.3 Decades ago, mitral valve prolapse (MVP) and mitral annulus disjunction (MAD) have already been associated with ventricular arrhythmias and sudden cardiac arrest (SCA) in young patients.4–13 In recent years, MAD regained attention in association with MVP and ventricular arrhythmias.8,14–17 MAD is defined as an abnormal atrial displacement of the mitral valve leaflet hinge point, away from the ventricular myocardium. Close relation has been shown to MVP and SCA but recent studies also showed an association with ventricular arrhythmias independently of MVP.8–10 Imaging with cardiac magnetic resonance imaging (CMR) and echocardiography is included in the standard work-up for IVF patients. Previous studies have reported a high prevalence of MVP in patients with aborted cardiac arrest of unexplained etiology9, but until now no specific attention has been given to the presence of MAD in IVF patients. We hypothesize that this abnormality might often have been overlooked in the routine clinical work up of IVF patients. The aim of this study was to describe MAD and MVP prevalence and morphology in a multicenter cohort of IVF patients and matched controls. METHODS Study population Patients were derived from a large Dutch registry of IVF patients. Details of the cohort have been published in previous studies.2,18 In summary, we enrolled patients with an unexplained cardiac arrest with an initial rhythm of ventricular fibrillation, in whom known cardiac, respiratory, metabolic, and toxicological causes were excluded at first presentation. Comprehensive clinical investigation was performed, and accepted diagnostic criteria were used to exclude specific disease.19 For this multicenter retrospective cohort study, we included IVF patients who were evaluated in three tertiary referral centers in the Netherlands (University Medical Center Utrecht, Amsterdam University Medical Center and Radboud University Medical Center) between September 2004 and December 2020 and underwent CMR imaging of sufficient image quality (Figure 1). Age- and sex-matched controls with no history of cardiovascular disease were selected from a previous prospectively included cohort of healthy non-athletes.20,21 The study complied with the Declaration of Helsinki and was approved by the Regional Committee for Medical Research Ethics in all participating centers and the subjects gave informed consent when appropriate. The data that support the findings of this study are available from the corresponding author upon reasonable request. 10
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