Introduction
Atrial fibrillation (AF) is the most common arrhythmia, and the
incidence and prevalence are increasing.1 Recently,
the benefits of rhythm control strategies in AF patients has been
spotlighted to a greater extent.2 For successful
rhythm control and prevention of complications, appropriate patient
selection is essential. In particular, the rhythm control strategy in AF
patients with slow ventricular response (SVR), who might have underlying
sick-sinus syndrome (SSS) or atrioventricular (AV) conduction
disturbance, requires greater attention. In these patients, pacemaker
implantation is an established treatment modality when the HR is less
than 40 bpm. The management of symptomatic AF patients with SVR, in whom
heart rate (HR) is in the gray zone between 40 and 60 bpm, is uncertain.
There is no definitive recommendation for electrical cardioversion in
patients with AF with SVR, and the outcome of rhythm control is unknown
for these populations. We present two cases of sudden cardiac arrest
with sustained ventricular tachycardia/fibrillation (VT/VF) after
electrical cardioversion of persistent AF with SVR.