Transvenous pulmonary vein (PV) isolation using radiofrequency energy is an effective treatment for atrial fibrillation (1-4). However, rare but potentially life threatening complications such as thromboembolism (5), PV stenosis (5-10), left atrium-oesophageal fistula (11) and inflammatory syndromes (12) have been described. In preliminary studies an alternate approach using cryoenergy induces less endothelial disruption/ thrombus formation (13), preserves the extra cellular matrix and creates lesions with well-delineated border zones (14). Therefore, cryoenergy seems to be the ideal form of energy to safely perform PV isolation.

We therefore hypothesise that in the setting of PV isolation for the treatment of atrial fibrillation (AF) cryoenergy is less traumatic and therefore reduces systemic inflammatory responses compared to radiofrequency energy.

78 patients presenting with symptomatic intermittent or persistent AF will be randomised to PV isolation with either radiofrequency (26 patients open irrigated tip, 26 patients closed irrigated tip) or cryoenergy (26 patients with cryoballoon). Systemic markers of cell damage and inflammatory response (t-troponin, CK, CK-MB, vWF, PAI-1, micro particles, platelet activation/overall function, CRP, IL-6, IL-8, IL-10, TNF alpha, procalcitonin) will be monitored before, during and 48h after the procedure. Further endpoints include time to PV-isolation and procedure related complications. Six month clinical follow-up will focus on freedom from AF and cardiovascular events.

Inclusion Criteria:

• Age between 18 and 75 years
• Symptomatic drug refractory (more than 2 antiarrhythmic drugs) paroxysmal or persistent AF
• Documentation of AF on 12 lead ECG and/ or Holter
• Left atrium of less than 55 mm
• Informed consent signed by the patient

Exclusion Criteria:

• Previous Ablation or operation for AF
• Contra-indication for heart catheterisation
• Cardioversion for AF during the 2 weeks before the procedure