Unusual Fibrillation in the Emergency Department After Fall

47-year-old man with dilated cardiomyopathy, ambulatory left ventricular assist device (Heartmate II, Thoratec Corporation, Pleasanton, CA), and biventricular pacemaker/implantable cardioverter-defibrillator (ICD) (St. Jude Medical, St Paul, MN) presented with syncope to a local hospital. He was hemodynamically stable and otherwise asymptomatic. His electrolyte panel was unremarkable. Initial ECG diagnosis (Figure 1) was unusual atrial fibrillation. On transfer to our hospital, ventricular fibrillation (VF) was suspected (asterisk in Figure 1), with likely undersensing by a defective ICD resulting in lack of defibrillation and lack of inhibition of atrial-biventricular pacing (arrows). There was pacing noncapture due to VF.Figure 1. Twelve-lead ECG.The ICD interrogation (left half of Figure 2) revealed persistent VF (asterisk in Figure 2) for …