Abstract 2316: Characteristics of Patients with Idiopathic Ventricular Fibrillation Triggered by High Vagal Tone
Background: Idiopathic ventricular fibrillation has been reported recently. Some of these patients experience ventricular fibrillation (VF) only during the high vagal tone period, such as during sleep or vasovagal reaction. Purpose: To investigate the clinical characteristics of idiopathic VF triggered by high vagal tone.
Methods and Results: Of 66 patients who underwent ICD implantation as a secondary prevention for VF, 10 patients had idiopathic VF (without structural heart disease including coronary spasm or obvious etiology of the VF, such as Brugada syndrome or long QT syndrome). Six out of 10 patients (3 male, age 35.8 +/− 16.9 y/o) were noted to have high vagal tone triggered VF. All patients had syncope, 3 with aborted sudden cardiac death, 1 with documented VF at vasovagal reaction while taking blood samples. ICD interrogation of these 6 patients showed 1.35 episodes/year (all during sleep), and 2 patients had electrical storm and underwent successful RF ablation; PVC trigger was found at tricuspid annulus in 1, RVOT in 1 patient). Although other patients had monomorphic PVC triggering VF, the episodes were very sporadic and not reproducible with EPS (including pharmacological test with edrophonium).
Conclusion: Patients with high vagal tone triggered VF are relatively young and have the monomorphic PVC triggering VF. Pharmacological stress test with vagotonic drugs may provoke the PVC, which may facilitate the successful ablation. Clinical entity of these patients should yet to be determined.