Fehmi Keçe

Summary and Conclusions 185 9 9.1 Aim of this thesis The aim of the first part of this thesis was to study the impact of advances in the development of AF devices on the incidence of complications. More specifically, the safety of the improved non-irrigated catheter (PVAC-Gold) was investigated. The first generation of this catheter showed a high incidence of asymptomatic cerebral embolism. Subsequently, the ablation device and protocol were revised to improve the safety of this device. Therefore, we investigated whether these revisions improved the incidence of cerebral infarcts by comparing it in a randomized fashion with an irrigated catheter. In addition, we performed in-depth analyses on the relationships between cerebral infarcts, activation of the coagulation system and the genesis of cerebral micro-embolisms. In the second part of this thesis, the ablation protocol for another new ablation device for pulmonary vein isolation, the cryoballoon ablation catheter, was investigated to prevent complications by optimizing the ablation duration. The development of the second-generation cryoballoon brought a significant improvement in terms of efficacy. To prevent complications however, the ablation duration still needed to be optimized. The second aim of this thesis was therefore to optimize the ablation duration by randomizing patients to different ablation durations using the incidence of dormant conduction as an indicator for incomplete isolation. Furthermore we tried to predict the absence of incomplete cryoballoon applications, making the standard waiting period after ablation unnecessary. The third aim of this thesis was to improve the ablation protocol in patients with persistent AF. We focused on posterior left atrial box isolation in patients with progressive left atrium illness and investigated the effect of the ablation surface area on the outcome of the ablation. In the general introduction, chapter 1 of this thesis, it is explained that with improvement of the ablation tools and techniques, AF ablation evolved to a first-line therapy over the last 20 years. In this chapter the knowledge about the AF mechanisms and the different ablation methods and tools are summarized. In chapter 2 the introduction continues by describing the advances in AF ablation devices and the incidence and prevention of complications. An overview of point-by- point, multi-electrode and balloon-based devices for pulmonary vein isolation is given with a detailed description of the ablation tools, reported complications and device- related specific aspects. The development of new ablation devices is often directed at increasing procedural efficacy, improvement of the safety profile is often delayed until unexpected complications occur. For point-by-point irrigated contact-force radiofrequency