Origin of recurrent syncope in patient with right ventricular outflow tract arrhythmias: evidence of autonomic modulation of the ectopic foci

To the Editor. Right ventricular outflow tract premature contractions (RVOT-PVCs) represent a subtype of idiopathic ventricular outflow tract arrhythmias characterized by a left bundle branch block (LBBB) and inferior-axis morphology [1]. RVOT-PVCs are more frequent during daytime than at night, are transiently suppressed by effort or sinus tachycardia, and occur in the absence of structural heart diseases. It has been hypothesized that RVOTPVCs are caused by triggered activity, possibly by a c-AMP-mediated mechanism [1]. However, a neural basis in animal and in human models has been reported [2,3]. Patients with RVOT-PVCs may present recurrent syncope or near-syncope, but most of the time it is not possible to establish a correlation between symptoms and rhythm changes by outpatient electrocardiogram (ECG) monitoring. Indeed, patients with recurrent syncope and RVOT-PVCs may present sustained ventricular tachycardia and/or not sustained ventricular tachycardia as the cause of syncope. However, syncope may also have a neurocardiogenic etiology. We present a case of recurrent syncope in a patient with RVOT-PVCs, in whom a neurocardiogenic etiology of syncope was diagnosed. Moreover, we demonstrate how the autonomic activity plays a relevant role in the modulation of RVOT-PVCs.