Self-terminated long-lasting ventricular fibrillation: What is the mechanism?

A 60-year-old woman with dilated cardiomyopathy was referred to our hospital due to recurrent syncope. The electrocardiogram recorded by an implantable loop recorder during a syncopal episode revealed an episode of ventricular fibrillation lasting almost 3 min that terminated spontaneously. A detailed analysis of the rhythm strip showed that the chaotic rhythm became an organized ventricular rhythm with a cycle length of 220 ms for the last 14 s before it terminated. <Learning objective: Ventricular tachyarrhythmias are one of the causes of syncope and have been observed in 1-3% of syncopal patients using an implantable loop recorder (ILR). However, long-lasting ventricular fibrillation (VF) as a cause of syncope is rare in clinical practice, because VF seldom terminates spontaneously. The long-lasting VF became an organized ventricular rhythm, and finally self-terminated as sinus rhythm was restored and this entire sequence of the arrhythmic events was recorded by an ILR.>.