Long-term prognosis of successfully resuscitated patients with idiopathic ventricular fibrillation after out-of-hospital cardiac arrest

Abstract Background Although previous studies reported that coronary artery disease is the most frequent cause of out-of-hospital cardiac arrest (OHCA), fatal ventricular arrhythmia is also a major contributor to OHCA. In-hospital examinations after successful resuscitation often detect arrhythmic diseases that trigger fatal ventricular arrhythmia. However, in some OHCA patients, no underlying organic cardiac disease is identified as the cause of cardiac arrest. These patients are diagnosed with idiopathic ventricular fibrillation (IVF). The Long-term prognosis of IVF patients after successful resuscitation has not been adequately reported. Methods A total of 2,593 OHCA patients were transferred to the institutional critical care center from January 2015 to December 2021. We ultimately included 256 patients, who achieved the return of spontaneous circulation and underwent in-hospital tests to determine the cause of cardiac arrest. These tests included electrocardiograms, coronary angiography, cardiac imaging evaluations (computed tomography, magnetic resonance imaging, or echocardiography) and drug-induced stress tests to detect severe coronary artery spasm, long QT syndrome, and Brugada syndrome. Among this cohort, 29 patients were diagnosed with IVF, in which no identifiable cause was found through in-hospital examination. We investigated their long-term clinical prognosis, including 30-day and 1-year survival rate, neurological status, and recurrence of VF. Neurological status was evaluated using the cerebral performance category (CPC) scale. Results Of the total cohort, the cause of VF was not identified in 29 patients (1.1%), who were diagnosed with IVF in the present cohort. Among them, 21 patients (72.4%) survived until discharge, and 19 patients exhibited favorable neurological outcomes: CPC scale 1 (65.5%) at 30 days. Sixteen patients (55.2%) survived one year later with a CPC scale of 1. Among the 21 patients who survived until discharge, an implanted cardiac defibrillator (ICD) was implanted in 15 patients as secondary prevention before discharge. During the long-term follow-up period, appropriate defibrillation was performed in 3 patients (3/15, 20%) and inappropriate defibrillation was detected in 3 patients (3/15, 20%). Short-coupled premature ventricular complexes (SC-PVCs) were not preceded in any patients who experienced recurrent VF (0/3, 0%), whereas Longer-coupled premature ventricular complexes were present in 2 patients (2/3, 66.7%). Conclusions Although more than half of IVF patients who experienced OHCA achieved 1-year favorable neurological outcomes at one year, some of them experienced recurrent VF after discharge according to institutional data.