Ablation in Patients With HF and Symptomatic AF: PULVERISE-AF-CRT

Inclusion Criteria: * Presence of a cardiac resynchronization therapy device (CRT-D or CRT-P) and optimal medical therapy according to current guidelines. * Patients with paroxysmal or persistent AF, having AF or HF related symptoms. * Patient with paroxysmal AF should have \>25% burden or inadequate biventricular pacing (\<95%) based on device counters. * The patient is willing and able to comply with the protocol and has provided written informed consent. * Age ≥ 18 years Exclusion Criteria: * Documented left atrial diameter \> 6 cm (parasternal long axis). * Longstanding persistent AF longer than 2 years. * Contraindication to chronic anticoagulation therapy or heparin * Previous left heart ablation procedure for AF * Acute coronary syndrome, cardiac surgery, angioplasty or stroke within 2 months prior to enrolment * Untreated hypothyroidism or hyperthyroidism * Enrolment in another investigational drug or device study. * Woman currently pregnant or breastfeeding or not using reliable contraceptive measures during fertility age. * Mental or physical inability to participate in the study. * Listed for heart transplant. * Cardiac assist device implanted. * Planned cardiovascular intervention. * Life expectancy ≤ 12 months. * Uncontrolled hypertension. * Requirement for dialysis due to terminal renal failure. * Participation in another telemonitoring concept