Pharmacological Tests in Atrial Fibrillation Ablation

Abstract

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia observed in clinical practice, occurring in approximately 2 % of the general population.1-3 A progressive increase in both the prevalence and incidence of AF has been demonstrated in recent years, defining AF as a major economic and public health issue. 1 The identification of sites of AF initiation and/or maintenance within the pulmonary veins (PVs) has led to the development of percutaneous procedures to electrically isolate the PVs from the left atrium (LA). 4 Large observational studies and multiple randomised-controlled trials have demonstrated that catheter ablation is universally superior to anti-arrhythmic drugs (AADs) for the maintenance of sinus rhythm (66-89 % versus 9-58 %, respectively) and results in a greater improvement in arrhythmia-related symptoms, exercise capacity and quality of life.1,2,5-8 As a result, catheter ablation has become the 'standard of care' for the maintenance of sinus rhythm in symptomatic patients in whom drugs are ineffective or poorly tolerated.While the results of ablation are unequivocally superior to medical therapy, they are unfortunately not flawless: approximately 30 % of paroxysmal AF patients will experience arrhythmia recurrence after a single ablation procedure.8 As most recurrences are in association with PV reconnection or as a result of non-PV triggers, several pharmacological challenges have been proposed to improve outcomes. [9][10][11][12] This article reviews the pathophysiological background and evidence for the use of pharmacological challenges during catheter ablation procedures. Pathophysiology of Atrial Fibrillation and Atrial Fibrillation Catheter AblationDespite decades of progress, there is no comprehensive pathophysiological explanation of AF. Early hypotheses postulated that AF resulted from the co-existence of multiple independent wavelets propagating randomly throughout the left and right atria (the 'multiple wavelet hypothesis'). 13,14 This hypothesis suggested that as long as the atria had a sufficient electrical mass, and an adequately short refractory period, AF could be initiated and indefinitely perpetuated. 15 Based on this theory, the early surgical interventions for AF were designed to reduce the excitable mass of atrial tissue by compartmentalising the atria into smaller regions incapable of sustaining a critical number of circulating wavelets. 16 Unfortunately this strategy has proved to be of limited efficacy and has been associated with a substantial risk of major complications. 17In the late 1990s, Haïssaguerre and colleagues demonstrated that AF is a triggered arrhythmia initiated by rapid repetitive discharges, predominantly from the proximal aspect of the PVs. 4 This discovery led to the development of percutaneous procedures to directly eliminate spontaneous focal ectopic activity within the PVs. However, early AF recurrences from the targeted and other nontargeted PVs led to modification of the ablation strategy to electrically isolate all of the PV...

Electrophysiological significance of the interatrial conduction including cavo‐tricuspid isthmus during atrial fibrillation

“…This is due to the developmental, anatomical, and electrophysiological differences between the LA and right atrium (RA) (Christoffels et al 2000;Mansour et al 2001). In addition, various ectopies originating from the LA, especially from the pulmonary veins or LA posterior wall, provide the induction mechanism of AF, and the action potential duration of the LA is shorter than that of the RA, facilitating the maintenance of the short wavelengths and micro-reentries (Qi et al 1994;Christoffels et al 2000;Aslanidi et al 2009;Gourraud et al 2016;Tutuianu et al 2016). Because of this, the main targets of radiofrequency AF catheter ablation are the pulmonary veins and LA posterior wall.…”

Catheter ablation of atrial fibrillation in heart failure with reduced ejection fraction

“…The complication rate per procedure ranged from 2.1% to 10.2% in the randomized trials with the exception of MacDonald et al . Most complications related to access site bleeding, and postprocedural infections.…”

“…Large‐scale observational studies and multiple randomized controlled trials have demonstrated that catheter ablation is universally superior to AADs for the maintenance of sinus rhythm (66–89% for ablation vs. 9–58% for AADs), and improving AF‐related symptoms, exercise capacity, and quality of life . The contemporary AF ablation procedure is centered on circumferential ablative lesions that are placed within the left atrial myocardium just outside the tubular veins with an ultimate goal of electrical pulmonary vein isolation (i.e., bidirectional conduction block).…”

Omega-3 Index and Anti-Arrhythmic Potential of Omega-3 PUFAs

“…Anti-arrhythmic drug therapies are often ineffective in terminating AF or preventing a recurrence of AF, possibly because these drugs target a single pathophysiological mechanism. Invasive approaches, using catheter ablation of arrhythmogenic triggers, do not prevent the recurrence of AF, likely because of the persistence of arrhythmogenic substrates and non-pulmonary vein triggers [ 46 ]. In advanced forms of AF, abnormal atrial substrates, including Cx43, Cx40 and Cx45 abnormalities, are thought to act as drivers of arrhythmia perpetuation.…”