Clinical Electrophysiology -> Ventricular Arrhythmias -> Mapping & Imaging D-AB10 - Ventricular Arrhythmias from Mechanism to New Ablation Targets (ID 52) Abstract Plus

D-AB10-02 - Alternating Impulse Formation In Left Sided Papillary Muscles. A Possible Role Of Inter Papillary Muscle Connections? (ID 1417)

  S. Rivera: Speakers' Bureau - Biosense Webster, Inc.; Medtronic.


Background: Papillary muscles (PMs) arrhythmia frequently exhibit multiple QRS configurations, which can impair mapping and treatment results. Occasionally, a shifting QRS axis suggests origins at both PMs.
Objective: To describe the incidence of bidirectional arrhythmia from the papillary muscles and propose possible mechanisms.
Methods: Patients (N=71) selected for PM arrhythmia ablation were analysed. Those with myocardial disease or anatomical variations were excluded. Patients with a shifting QRS axis during the same arrhythmia run (ventricular tachycardia or couplets) suggesting an origin at both papillary muscles were analysed. Their site of origin was determined by activation mapping. Cardiac resonance was analysed for the presence of Inter-papillary muscle connections (Inter-PMC) suggesting a sub-valvular mitral valve apparatus disarray and correlate them to those with and without bidirectional arrhythmia.
Results: Eleven out of 44 patients (25%) presented arrhythmias originating at both papillary muscles. Nine of them showed QRS axis alternation, which in six was eliminated by single papillary muscle ablation. Inter papillary muscle connections were observed in 32% (N=14). A strong correlation with biventricular arrhythmia was observed (100% vs. 11%; P=<0.001). Overall recurrence rate was 32% (N=14) at 411 ± 380 days mean follow-up. Survival free rate of clinical arrhythmia after catheter ablation was 56% and 81% comparing those with and without Bidirectional papillary muscle arrhythmia.
Conclusion: Bidirectional papillary muscle arrhythmia is a novel observation. Our findings suggest a strong correlation with the presence of muscular connections between both papillary muscles. Impulse propagation or stretching-like phenomena could occur simultaneously between these structures, resulting in bidirectional beats. This is supported by the fact that 66% of patients exhibiting bidirectional arrhythmia were eliminated by ablating a single papillary muscle. Recurrence was higher in those with a complex anatomy.