Novel approaches to mechanism-based atrial fibrillation ablation.

Modern cardiac electrophysiology has reported significant advances in the understanding of mechanisms underlying complex wave propagation patterns during atrial fibrillation (AF), although disagreements remain. One school of thought adheres to the long-held postulate that AF is the result of randomly propagating wavelets that wonder throughout the atria. Another school supports the notion that AF is deterministic in that it depends on a small number of high-frequency rotors generating three-dimensional scroll waves that propagate throughout the atria. The spiralling waves are thought to interact with anatomic and functional obstacles, leading to fragmentation and new wavelet formation associated with the irregular activation patterns documented on AF tracings. The deterministic hypothesis is consistent with demonstrable hierarchical gradients of activation frequency and AF termination on ablation at specific (non-random) atrial regions. During the last decade, data from realistic animal models and pilot clinical series have triggered a new era of novel methodologies to identify and ablate AF drivers outside the pulmonary veins. New generation electroanatomical mapping systems and multielectrode mapping catheters, complimented by powerful mathematical analyses, have generated the necessary platforms and tools for moving these approaches into clinical procedures. Recent clinical data using such platforms have provided encouraging evidence supporting the feasibility of targeting and effectively ablating driver regions in addition to pulmonary vein isolation in persistent AF. Here, we review state-of-the-art technologies and provide a comprehensive historical perspective, characterization, classification, and expected outcomes of current mechanism-based methods for AF ablation. We discuss also the challenges and expected future directions that scientists and clinicians will face in their efforts to understand AF dynamics and successfully implement any novel method into regular clinical practice.

Long-term follow-up of right atrial ablation in patients with atrial fibrillation:.

INTRODUCTION: The aim of this study was to evaluate the efficacy and the impact on quality of life of a new ablative approach to the right atrium in patients with atrial fibrillation (AF). METHODS AND RESULTS: Seventy-four symptomatic patients with paroxysmal (n = 49) or permanent (n = 25) refractory AF underwent radiofrequency ablation. A nonfluoroscopic electroanatomic mapping system was used to perform the following lesions: (1) an isthmus line between the tricuspid annulus and the inferior vena cava; (2) a posterior intercaval line from the superior vena cava and the inferior vena cava; (3) a septal line from the superior vena cava to the fossa ovalis, proceeding to the coronary sinus ostium where a circumferential line around the ostium was performed, and then on to the inferior vena cava; and (4) a transversal lesion connecting the posterior intercaval and the septal lesions. In addition, electrical disconnection of the superior vena cava was performed. There were no complications. Postablation remapping showed the absence of discrete electrical activity inside and just around the ablation lines. Electrical disconnection of the superior vena cava was obtained in all patients. After 21 +/- 6 months, 49 patients (66%) had stable sinus rhythm with continuation of the previous antiarrhythmic drug therapy, 13 patients (18%) were considered improved, and 12 (16%) received no benefit (unsuccessful procedure). After ablation, quality of life was significantly improved, reaching the levels of the general Italian population. Ejection fraction and the extent of the low-voltage area were found by multivariate analysis to be independent predictors of AF recurrence. CONCLUSION: The results of the present study suggest that this ablative approach in combination with antiarrhythmic drugs is safe and effective in treating AF, leading to a marked increase in quality of life in patients with refractory AF.