Is Endothelial Function a Predictor of Successful Ablation Therapy Provided to Patients With Atrial Fibrillation?

Inclusion Criteria: * All patients with AF considered eligible for ablation treatment may be included in this study (following unsuccessful attempts with AAD). * Patients on optimal anticoagulation therapy * The minimum AF documentation required as defined by the Heart Rhythm Society Exclusion Criteria: * Patients age below 18 years * Cases with extremely abnormal anatomy (i.e., inverted heart) * Moderate or severe mitral valve disease or mitral prosthetic valve * Ejection fraction less than 30% * Left atrial anteroposterior diameter more than 50 mm evaluated by echo or CT data (up to 6 months old).. * Previous atrial fibrillation ablation occurred less than 6 months prior * Left atrium thrombus * Acute infective disease or sepsis in the last 3 months * Acute myocardial infarction in last 3 months * Reduced expectancy of life (less than 12 months) * Patient participating in another clinical study that investigates a drug or device unless prior approval is given by the sponsor * Psychologically unstable patient or denies to give informed consent * Deformities of the digits of the upper extremities, which preclude adequate signal acquisition * Patients under the effect of short-acting Nitroglycerin (3 hours washout period) * Patient suffering from a medical condition prohibiting blood flow occlusion in both arms