The MAGiC™ Cardiac Ablation European Study (MAGiC-FEST)

Inclusion Criteria: Adult (aged 18 or older at time of consent); Eligible for ablation procedures of an atrial or ventricular arrhythmia per European Heart Rhythm Association (EHRA) guidelines, with at least one (1) documented episode of the tachyarrhythmia to be treated within the previous six (6) months; Able to be safely exposed to magnetic fields; Willing and capable to attend scheduled follow up visits at the investigational site for the study duration (up to 12 months) Willing and able to provide informed consent. Exclusion Criteria: Unable to be safely exposed to magnetic fields due to Magnetic Resonance Imaging Unsafe device (implanted device or device that cannot be safely removed for the procedure) Unable to remain comfortable or hemodynamically stable in the supine position for an extended period of time Weight exceeding 200 kg (the weight limit of the table) For female patients of childbearing potential: pregnancy at the time of the procedure or unwilling to take a pregnancy test Presence of intracardiac thrombus at the time of the procedure Where MAGiC would need to cross a prosthetic valve Use of MAGiC in the coronary arteries A history of sensitivity to foreign objects or extreme allergies Acute illness or active systemic infection Histological or anatomical abnormalities that may lead to post-operative complications including diminished resistance to infection Hemodynamic instability Unable to receive heparin or an acceptable alternative to achieve adequate anticoagulation Acute myocardial infarct (within the previous 30 days) Recent cardiac surgery (within the previous 60 days) Unstable angina History of embolism (cerebrovascular accident, transient ischemic attack, systemic embolism) in the previous 30 days Previous cardiac ablation within the previous 30 days Concomitant arrhythmia(s) requiring active treatment at this time or in the 90 days prior to enrollment (Day -90 to Day 0) Currently or in the 30 days prior to consent, participation in an interventional clinical trial Significant uncontrolled or unstable medical problems which, in the opinion of the Investigator, would preclude enrollment in and completion of the study (limitation on survival). Any reason or condition that, in the judgement of the investigator, makes the patient ineligible for the investigation. For Atrial Fibrillation only: persistent Atrial Fibrillation (continuous Atrial Fibrillation lasting longer than 7 days) For Atrial Fibrillation only: Presence of any device that would interfere with planned access: Patent Foramen Ovale occlusion/closure device, patch