EndoMAZE HYBRID

Atrial fibrillation (AF) represents the most common sustained cardiac arrhythmia with a prevalence of nearly 2% in general population [1]. It increases with age and the number of patients suffering from AF in Europe is expected to double within next 10 years. Presence of any type of AF is associated with two-fold raise of mortality, five-times increased risk of cerebrovascular thromboembolic events (mainly stroke), increased rate of cardiac-related hospitalisations and also a deteriorative quality of life [2]. It can be unrecognised for a long time and manifest suddenly as a stroke or stealthily as limitation of exercise, fatigue and shortness of breath. With a rapid response of ventricules, it can sometimes lead up to cardiac insufficiency. Because of its serious social and financial impact, AF is sometimes called an epidemic of the 21st century. One of the reasons is that an effective treatment of AF still remains an unresolved problem.

Atrial fibrillation is a chronically progressing arrhythmia. It usually starts with self-terminating paroxysms. Those paroxysms gradually become more often or later do not terminate spontaneously at all (persistent form of AF). Its pathophysiology becomes more and more complicated as it persists over time, and its treatment also becomes more complicated and less successful. It can be treated with two basic strategies. First strategy leaves patients in AF. Medicaments are given to control the heart rate (beta-blockers, digoxin etc.) and to prevent the thromboembolic events (anticoagulants, mainly warfarin or new oral anticoagulants - NOAC). However, the stroke volume remains decreased, as it is without the contribution of heart atrias systole and patients remain in a risk of thromboembolism or more frequently of bleeding, because of anticoagulants. The frequency of any (major or minor) bleeding during NOAC treatment was described approximately 6-16% per year.

The second strategy tries to convert the AF back to the normal sinus rhythm (SR) and maintain it (rhythm-control strategy). This can be done either with medicaments (antiarrhythmic drugs, AADs) or electric cardioversion, but these methods are failing especially in treatment of persistent and long-standing persistent AF. This imperfect efficacy and also a potential toxicity of AADs have prompted electrophysiologists and cardiac surgeons to create and to improve interventional ways of AF treatment in the past decades. A breakthrough discovery was published by Haissaguerre in 1998, who has described the key role of pulmonary veins in formation of AF [3]. Since then, the isolation of pulmonary veins is a key component of very most of AF ablation procedures. In cardiac surgery, the Cox-Maze procedure and its modifications [4] have been successfully incorporated into current recommendations and guidelines for treatment of patients with AF who undergo a cardiac surgery for some structural heart disease [5].

Different treatment options exist for patients with stand-alone type of AF (SA-AF), i.e. where AF is present without any other significant structural heart disease. For those patients, a big, open heart arrhythmia surgery is in most centres considered too invasive. Therefore a plenty of minimally invasive surgical procedures and transvenous catheter procedures were introduced and currently present a very dynamically evolving part of cardiology and cardiac surgery.

Paroxysmal AF is standardly treated in electrophysiology (EP) laboratories nowadays [6]. Recent systematic review and meta-analysis of catheter ablation long-term outcomes describes efficacy of 60% after one procedure and 80% after multiple procedures for patients with paroxysmal AF [7]. In field of minimally invasive cardiac surgery for AF, an early review of mid-term results of those methods was published by Mack in 2009: an overall freedom from AF off of AADs after 6-12 months was 65% (57-87%) with better results for paroxysmal AF [8]. For patients with persistent and long-standing persistent type of SA-AF, the situation is much more complicated. In catheter ablation, many different methods have been added to pulmonary veins ablation, such as the deployment of a very wide ablation around the PV ostia [9, 10], linear ablation lesion (roof or mitral line), ablation of complex atrial fractionated electrograms [11], ganglionated plexi ablation [12], and non-PVI trigger (such as superior vena cava) ablation. However, results of catheter or miniinvasive surgical ablation of non-paroxysmal AF remain unsatisfactory [7, 8, 13].

Most lately, a hybrid approach for treatment of SA-AF was introduced, combining an epicardial minimally-invasive surgery with a following percutaneous catheter ablation [14]. It represents a very elegant option of how to use the advantages of both surgical and electrophysiological procedures and also how to avoid their disadvantages. Recent review of initial results was published by Gelsomino in 2014. The success rates of freedom from AF without AADs after one year ranged from 85.7% to 92% in papers employing bipolar radiofrequency, and from 36.8% to 88.9% with the usage of monopolar radiofrequency [14]. With those results, the hybrid procedure may represent a potential method of stand-alone AF treatment with higher success rates than other concurrently existing methods.

The aim of our project is to describe in detail the efficacy and safety of two-stage hybrid ablation of persistent and long-standing persistent, stand-alone atrial fibrillation. The hybrid procedure will consist of fully thoracoscopic, bilateral surgical posterior left atrial wall ablation (creation of box lesion) and left atrial appendage (LAA) closure and subsequent electrophysiological examination with the box lesion evaluation (or completion) and right cavotricuspid isthmus catheter ablation.

• Expert guarantors: Petr Budera, MD, PhD (Department of Cardiac Surgery, Third Faculty of Medicine at Charles University), Assoc. Prof. Pavel Osmančík, MD, PhD (3rd Department of Internal Medicine and Cardiology, Third Faculty of Medicine at Charles University)

References

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