[Interventional therapy of atrial fibrillation: possibilities and limitations]

Abstract

Recently, significant progress has been made treating atrial fibrillation (AF) with catheter ablation emerging as an increasingly important technique. Electrical disconnection of the pulmonary veins (PV) is a widely accepted endpoint for interventional treatment of paroxysmal AF (PAF). According to the current guidelines, catheter ablation can be considered as a therapeutic option in patients who failed antiarrhythmic drug treatment for PAF. The procedural endpoint for PVI is achievement of permanent electrical isolation of the PVs, which in the vast majority of patients harbor triggered electrical activity inducing and maintaining PAF. The success rate of this approach in patients with PAF ranges between 60 and 80% after a single procedure and augments to > 80 % in patients undergoing a repeat procedure to abolish recovered PV connection. However, it is now evident that persistent or long-standing persistent AF may not be successfully treated by PVI alone since the majority of patients have AF maintaining substrate beyond the PV. From a pathophysiological perspective this is explained by structural and electrical remodeling of the atrial myocardium in patients with persistent AF. Therefore, it is today widely accepted that additional substrate modification is required to effectively address persistent AF using catheter ablation. It has been shown that a combined approach of PV isolation, ablation of fractionated atrial electrograms and application of lines to treat atrial macro-reentrant tachycardias ("stepwise approach") aiming for restoration of sinus rhythm is a favorable strategy to treat persistent AF. However, significant expertise is needed to accomplish all steps within these complex procedures. Therefore, catheter ablation for persistent AF cannot yet be considered "clinically established" and should only be performed in high volume centers. Additional data is needed to verify the beneficial effect of this strategy and determine "predictors" identifying patients profiting most from these ablation strategies. In patients with PAF, catheter ablation has emerged as an established therapy also in comparison to antiarrythmic drug treatment. Recent studies have shown that catheter ablation for PAF is superior to antiarrhythmic drug treatment with regard to mid-term suppression of any atrial arrhythmia. Overall, catheter ablation for AF has still to be considered as a symptomatic treatment since evidence for beneficial effects with regard to more robust clinical endpoints such as death, rehospitalization and ischemic cerebral events are not yet available.