Soichi Muraoka

Characteristics of the conduction of the left atrium in atrial fibrillation using non-contact mapping

BACKGROUND We evaluated the conduction properties of the posterior left atrium (LA) using a non-contact mapping (NCM) system as well as the significance of linear ablation at the roof of the posterior LA (LA roof) and inferior region of the posterior LA (LA bottom). METHODS AND RESULTS In 133 patients with atrial fibrillation (AF) (83 paroxysmal type, 50 persistent/long-lasting persistent type), we performed complete isolation of the posterior LA including pulmonary veins (Box isolation) using NCM. Isochronal activation maps were analyzed during sinus rhythm (SR), during pacing from the proximal coronary sinus (CS), and during pacing within the posterior LA before and after ablation. In sinus rhythm, horizontal conduction along the LA roof line, but not into the posterior LA wall, was observed in 59% of the patients. During paroxysmal CS pacing, horizontal conduction along the LA bottom line was observed in 69% of the patients. Posterior wall pacing conducted vertically over the LA roof and bottom lines in 98% and 83% of the patients, respectively. During AF, rotor wave conduction into the posterior LA through the LA roof and bottom lines was observed in 85% of the patients. Heterogeneous conduction directions in the posterior LA at the LA roof and bottom lines were observed in 60% of the patients. CONCLUSIONS Heterogeneous conduction was observed at the roof and inferior region of the posterior LA in most of these AF patients. The conduction properties of the posterior LA are affected by the direction of the wavefronts, and this may play an important role in the initiation and maintenance of AF. The complete isolation of the posterior LA may prevent AF.

Efficacy and Safety of Catheter Ablation for Persistent or Permanent Atrial Fibrillation

Introduction: Radiofrequency catheter ablation (RFCA) that targets pulmonary veins (PV) is an established treatment for paroxysmal atrial fibrillation (PAF). Recent studies have demonstrated that RFCA can eliminate PAF in over 90% of patients. However, the effectiveness for persistent or permanent AF has not been clarified.

Efficacy of Additional Amiodarone Therapy in Patients with an Implantable Cardioverter-Defibrillator

Introduction: We examined whether the additional use of amiodarone (AMD) under implantable cardioverter‐defibrillator (ICD) therapy may have beneficial effects in patients at risk for lethal ventricular arrhythmias with structural heart diseases.

Does Atrial-Pacing from Different Intra-Atrial Sites for Atrial Fibrillation Effect Pulmonary Venous Pressure?

Introduction: Coronary sinus (CS) and biatrial pacing have been reported to be more effective than right atrial appendage (RAA) pacing for preventing atrial fibrillation (AF). However, the effects of atrial pacing on hemodynamics are still unknown.