Study population
This was a retrospective, single centre analysis of consecutive patients with systolic heart failure undergoing catheter ablation for AF at the Barts Heart Centre from 1st January 2008 to 30th March 2018. Patients were included if they: (1) had documented pre-procedural LVEF ≤45% as determined by either echocardiography or cardiac MR within 6 months of the index procedure; (2) underwent index catheter ablation for AF incorporating de-novo pulmonary vein isolation with cyroballoon (CRYO). Patients were excluded if (1) they had <12 months of follow up; (2) had previous left atrial ablation for AF; (3) if clinical data was incomplete. This study was approved by the hospital’s relevant governing body (clinical effectiveness unit approval number: 10573).