This prospective observational study is designed to describe the factors determining the success of pulmonary vein isolation (PVI) for patients with persistent atrial fibrillation (AF). These factors - described as left atrial (LA) function - are simultaneously studied by multi-modal techniques in patients undergoing radiofrequency ablation. The simultaneous measurements are conducted before the PVI in AF and after the sinus rhythm converted due to PVI. These measurements include invasive LA pressure monitoring, LA voltage map creation, LA strain evaluation by transthoracal echocardiography, LA scar-mapping by cardiac MRI, defining biomarkers from blood samples. During the one year follow-up period rhythm monitoring is conducted by regular Holter-monitoring. Our aim is to define the predictive values of the above mentioned factors and to create a new score system for predicting PVI success in persistent AF population.

Inclusion Criteria:

• documented, symptomatic persistent atrial fibrillation (AF)
• catheter ablation is indicated
• aged 18-75 years
• signed Patient Informed Consent Form
• able and willing to comply with all pre-, post-, and follow-up testing and requirements

Exclusion Criteria:

• secondary AF
• paroxysmal, long-standing persistent or permanent AF
• ejection fraction < 30%
• GFR <30 ml/min/1.73m2
• unstable angina pectoris or myocardial infarction within the past 2 months
• severe heart failure (NYHA IV)
• severe COPD (GOLD III-IV)
• previous left atrial catheter ablation
• previous transthoracic cardiac surgery
• implanted cardiac device (pacemaker, ICD, CRT, VAD)
• awaiting cardiac transplantation or other cardiac surgery within the next 12 months
• any contraindication for pulmonary vein isolation, MRI or anticoagulation
• coagulopathy
• active malignancy, left atrial myxoma
• autoimmune disorder, chronic inflammatory disease
• acute illness, active systemic infection, sepsis
• women who are pregnant, breast feeding, or planning to become pregnant in the next 12 months
• aged under 18 years or above 75 years
• enrollment in other studies, which exclude participation in other studies
• patient not willing or not able to sign the informed consent form

Patients with persistent atrial fibrillation referred for pulmonary vein isolation at Heart and Vascular Center of Semmelweis University, Budapest, Hungary.