Atrial Tachyarrhythmias With Ultra-Rapid Ventricular Response and Sudden Death in Patients Without Structural Heart Disease.

Background: Sudden cardiac death (SCD) is generally associated with life-threatening ventricular arrhythmias. Supraventricular arrhythmias are an accepted cause of SCD in Wolff-Parkinson-White syndrome and complex congenital heart disease. However, the role of atrial tachyarrhythmias (ATAs) in SCD in patients with structurally normal hearts is unclear.

Objectives: The goal of this study was to present data on resuscitated patients without structural heart disease (SHD), experiencing recurrent implantable cardioverter-defibrillator (ICD) shocks, who share common clinical and electrical features suggesting that ATAs can cause SCD.

Methods: We describe the clinical characteristics and ICD analysis of syncopal events terminated with shock delivery in 5 young SCD survivors without SHD. Details on the follow-up after ablation of the arrhythmia causing the syncopal episode are also reported.

Results: In all patients (4 male, 1 female; median age 23 years; age range 15-47 years), a surface electrocardiogram recording in the resuscitation setting suggested ventricular fibrillation. After the index event, all patients exhibited recurrent arrhythmic syncopal episodes in a setting of elevated adrenergic tone, treated with ICD shocks. ICD interrogation suggested ATAs (atrial fibrillation in 4 patients, atrial tachycardia in 1 patient), conducting to the ventricles at rates approaching 300 beats/min, as the underlying arrhythmia leading to the syncopal events. ATA ablation abolished episodes of arrhythmic syncope and shock delivery in all patients after a median follow-up of 34 months. No patient died suddenly during follow-up.

Conclusions: Common clinical and electrical features define a distinct entity of SCD caused by ATAs with ultra-rapid ventricular response in otherwise healthy patients. Catheter ablation of the ATA is an effective treatment in these patients.