Abstract 16463: Rotor-Based Ventricular Fibrillation Exhibits Greater Surface Electrogram Voltage Variation Compared to Focal Source-Based VF Due to Complex Rotor Behavior: A Clinical and Computational Study

Introduction: Ventricular fibrillation is a common fatal arrhythmia. The ECG of VF appears chaotic but may be useful to non-invasively identify VF-sustaining mechanisms to guide therapy. Hypothesis: We hypothesized that rotors and focal sources manifest distinct features on the ECG. Computational modeling may identify the mechanistic basis of these features. Methods: VF was induced at EP study in 31 patients referred for ventricular arrhythmia ablation. Simultaneous ECG and intracardiac recordings were obtained using biventricular basket catheters. Endocardial phase maps mechanistically classified each VF cycle as rotor or focal source. ECGs of each VF mechanism were compared using 3D voltage variation criteria. To control for patient differences, ECGs were analyzed only from patients demonstrating both mechanisms. Biventricular computer simulations of VF driven by focal sources or rotors were created. The ECGs and activation patterns of each simulated VF mechanism were analyzed. Results: Eight patients had periods of both VF mechanisms. Rotor-based VF exhibited greater voltage variation than focal source-based VF (57±15% vs 25±17%, p=0.004, Fig 1A-B). Simulations revealed similar differences between rotors (Fig 1E) and focal sources (41±15% vs 21±4%, p=0.02, Fig 1C). Modeling revealed that greater voltage variation may be due to wavebreak and secondary rotor initiation often in the contralateral ventricle. Conversely, single stationary rotors had minimal voltage variation (25±11% vs 41±15%, p=0.03, Fig 1D). Conclusions: In conclusion, controlled clinical and computational studies reveal that quantitative criteria of ECG voltage variation differ significantly between VF-sustaining mechanisms. Wavebreak and secondary rotor initiation contributes to such variation. Future studies should prospectively evaluate if these criteria can separate VF mechanisms and guide therapy such as anti-arrhythmic medication choice or substrate ablation.