Study design
Observational study in four European centres. We included all patients aged over 18 with confirmed diagnosis of HCM undergoing a catheter ablation for AF. According to the guidelines of the European Society of Cardiology [2], HCM was defined as a wall thickness ≥15 mm in one or more left ventricular myocardial segments (on either echocardiogram or cardiac magnetic resonance imaging) that is not explained solely by loading conditions. Participants needed to be on effective oral anticoagulation (VKA, apixaban, edoxaban, rivaroxaban, or dabigatran) for at least 30 days before the procedure to be considered for inclusion. Patients on VKA had a target INR of 2-3. Peri-procedure interruption or continuation of the oral anticoagulants, with or without heparin bridging, was based on the local protocol of each centre at the time of the ablation. In patients elected to VKA interruption with heparin bridging, the VKA was substituted 3 days before the procedure with enoxaparin 100 IU/kg twice a day or dalteparin 200 IU/kg daily. All patients provided written informed consent prior to the procedure. The study complied with the Declaration of Helsinki and the research protocol was approved by the local ethics or audit committees.