Study design
This retrospective study was performed reviewing the procedural reports patients undergoing a repeat ablation. Data collection included patients’ characteristics at initial and redo procedures, number and characteristics of previous ablations, type and location of accessory pathway, type of access, type of catheter and energy used, type of imaging to guide the procedure and procedure duration. The most probable reason for recurrence was determined by the operator based on the prior reports and on the findings during the redo procedure. The initial reasons for failure and /or recurrence were classified as 1, inaccurate mapping or diagnosis, 2, inadequate lesion formation due to poor contact, deep/epicardial location or inadequate energy delivery, 3, inadequate long-term lesion consolidation due to the use of cryoenergy as source of energy, or 4, unknown (in the case the cause remained unclear). The differences between the initial procedure and the final procedure were compared. Recurrence was defined as reappearance of anterograde accessory pathway conduction or documented supraventricular tachycardia. Long-term success was defined as no recurrence of accessory pathway conduction, no documented supraventricular tachycardia, or palpitations during at least 6 months of follow-up after the redo procedure.