A Prospective Multi Centre Trial on Bipolar Radiofrequency Ablation of Atrial Fibrillation

St. Olavs Hospital, Oslo University Hospital, Haukeland Sykehus HF, Ullevaal University Hospital, Regionssykehuset i Tromsø HF, Feiringklinikken

The study is a prospective multi-centre study to investigate the effect of a new bipolar ablation strategy of the left atrium in patients with paroxysmal or permanent atrial fibrillation over time.

Atrial fibrillation (AF) is the most common persistent arrhythmia, prevalent in about 6% of the population over 65 years of age. AF reduces the quality of life and increases mortality. AF is particularly common in combination with mitral valve disease, but is also detected in about 5% of patients with aortic valve and coronary artery disease. Surgical treatment of AF with the Cox-maze III operation was developed by J. Cox during the 80ies. The aim of the operation is to block spread of irregular electrical activity by creating lines of isolation in the atrial musculature. The operation achieves sinus rhythm in over 90% in selected patients. Nevertheless the method was only used in few heart surgical centres, because it is complex and time consuming.In recent years alternative energy sources have been developed to create isolating lines without cutting the tissue and thus making ablation treatment easier. Bipolar radiofrequency ablation is special because the energy is delivered feedback controlled until transmurality is achieved. This is a prerequisite for a good result and makes using the equipment safer. Since the development of the Cox-maze procedure, our knowledge of atrial fibrillation and its treatment has increased considerably. There is a consensus that the posterior part of the left atrium and in particular the pulmonary veins are an important target for treatment. Surgical ablation with alternative energy sources is a new method under continued development and evaluation. The optimal ablation treatment is unknown. A balance between invasiveness and achieving sinus rhythm in as many as possible has to be found. Creating numerous ablation lines in both atria is time consuming and leads probably to an increased need for permanent pacemaker implantation and reduced contractility of the atrial tissue. On the other hand can a simple bipolar ablation of pulmonary veins performed easily, but this is probably an insufficient treatment for most patients. In the protocol a new method using solely bipolar ablation for creation of several ablation lines in the left atrium is described. The study is a prospective multi-centre study to investigate the effect of a new bipolar ablation strategy of the left atrium in patients with paroxysmal or permanent AF over time.

Inclusion Criteria: referred for elective heart surgery with extracorporeal circulation suffers from AF for more than 6 months but less than 7 years aged between 18 and 80 years ejection fraction above 30 % Exclusion Criteria: Reoperations NYHA class IV Ischemic mitral incompetence Creatinine > 140 Transmural myocardial infarction < 4 weeks Endocarditis Serious peripheral vascular disease Pregnancy or breast-feeding Drug addiction Size of left atrium > 60 mm in preoperative echo-doppler investigation. Disease or other condition when the patient is unable to understand the objectives and the scope of the study.