Patients with atrial fibrillation (AF) and heart failure with reduced left ventricular ejection fraction (HFrEF) are at particularly high cardiovascular risk. Rhythm-control by means of catheter-based pulmonary vein isolation (PVI) reduces all-cause mortality and rehospitalization for worsening heart failure in these patients. Considering the globally increasing use of the novel "pulsed-field ablation", it is necessary to determine whether this technique can be performed with the same safety and efficacy as the established cryoballoon ablation (CRYO) in this critically ill patient population.

This retrospective, international, multicenter study compares the efficacy and safety of PFA versus CRYO in patients with AF and HFrEF (LVEF ≤40%) undergoing a first-time PVI-only procedure.

Using propensity-score matching to minimize selection bias, the study will retrospectively evaluate whether a non-thermal PFA approach is non-inferior to the established thermal CRYO technique regarding rhythm control, while comparing procedural safety and efficiency in this high-risk population. Non-inferiority is tested against the assumption of a 12-month recurrence rate of 30% with a prespecified non-inferiority margin of 12% (corresponding to a hazard ratio of 1.53).

Inclusion Criteria:

1. Patients with paroxysmal or persistent AF and echocardiographically confirmed HFrEF (LVEF ≤ 40%)
2. Patients who underwent their first PVI using pulsed field or cryoballoon ablation as part of clinical routine
3. Patients with regular follow-up via 12-lead ECG or Holter ECG following PVI
4. Patients with at least three months of follow-up

Exclusion Criteria:

1. Patients who did not undergo pulsed field or cryoballoon ablation for first-time PVI
2. Patients with LVEF > 40%
3. Patients who declined the use of their data during initial collection

Patients with atrial fibrillation and heart failure (LVEF ≤ 40%)