Localized Structural Alterations Underlying a Subset of Unexplained Sudden Cardiac Death

Area of Science:

• Cardiology
• Electrophysiology
• Sudden Cardiac Death

Background:

• Sudden cardiac death (SCD) due to ventricular fibrillation (VF) in young individuals often remains unexplained.
• Detailed electrophysiological mapping studies in these patients are scarce.

Purpose of the Study:

• To investigate the underlying mechanisms of idiopathic ventricular fibrillation (VF) in young survivors.
• To identify drivers of VF and associated structural or electrical abnormalities.

Main Methods:

• Evaluated 24 idiopathic VF survivors using multielectrode body surface recordings to map VF drivers.
• Performed endocardial and epicardial catheter mapping during sinus rhythm to analyze electrograms in driver regions.
• Assessed for structural alterations using established electrogram criteria.

Main Results:

• VF drivers were predominantly reentrant (87%).
• Localized structural alterations were found in 62.5% of patients, primarily on the epicardium and colocated with VF drivers.
• Purkinje triggers were more common in patients without structural alterations (7/9).
• Catheter ablation achieved an arrhythmia-free outcome in 15/18 patients.

Conclusions:

• Localized structural alterations are a significant cause of previously unexplained SCD.
• Purkinje electrical pathology appears to be a dominant mechanism in a subset of these patients.
• Electrophysiological mapping can identify specific targets for ablation, improving outcomes.