Fehmi Keçe

General Introduction 13 1 1.1 The Era of Atrial Fibrillation Ablation More than 33 million people worldwide have atrial fibrillation (AF), with a progressive increase in overall burden, incidence, prevalence and AF associated mortality (1). It is the most common tachycardia with reduction of quality of life necessitating frequent hospitalizations and high risk for complications, especially thrombo-embolic events (2). AF occurs more frequently in patients with underlying heart disease, e.g. heart failure, ischemic cardiomyopathy and valvular heart disease but it can also occur in the absence of structural heart disease. Besides these specific causes for AF, also risk factors (obstructive sleep apnoea syndrome, metabolic syndrome and hypertension) contribute to the genesis of AF and are therefore significant treatment targets. The general classification of AF, described in the European society of Cardiology Guidelines is that of paroxysmal versus persistent AF (3), which is a rhythm-based classification. While this classification system is clinically useful, it does not reflect the underlying pathophysiology and substrate characteristics of the atria (4). To improve the treatment of AF however, understanding the pathophysiology of AF is of great importance. The two main objectives in the treatment of symptomatic AF are stroke prevention and restoration and maintenance of sinus rhythm. While stroke prevention can be managed by oral-anticoagulation therapy, the pharmacological treatment to maintain sinus rhythm is limited by systemic toxicity, low efficacy and arrhythmogenicity (5). Therefore, interventional therapy of AF advanced to a serious alternative treatment strategy during the past decades (2). The first surgical AF ablation in humans, the Maze procedure, was performed in seven patients concomitant to cardiac surgery in 1987 (6). The Cox-Maze procedure was effective with AF-free survival of 94% at 12 months (7), however it was also associated with significant chronotropic incompetence and the requirement of pacemaker implantation. In current practice the Cox-Maze-IV procedure is the gold-standard surgical treatment with high efficacy and safety. Cather ablation was performed for the first time around the year 2000 and has undergone impetuous advances over the last 20 years. In the Introduction section of this thesis, the pathophysiology of AF and the development of catheter ablation tools will be further discussed, with emphasis on the tools, techniques and safety.