Electroanatomic mapping of recurrent atrial arrhythmias after surgical cryomaze: insights from a single-center retrospective study

Background/Introduction

Surgical cryoablation performed during open heart surgery provides an effective rhythm control strategy for atrial fibrillation (AF) or atrial flutter. However, recurrences may occur due to incomplete lesion sets or conduction recovery. Understanding the electrophysiological characteristics of these recurrences can improve both surgical and catheter ablation strategies.

Purpose

To analyse electroanatomic mapping findings in patients presenting with recurrent atrial arrhythmias after surgical cryoablation and to identify incomplete or non-conductive lesions requiring complementary radiofrequency (RF) ablation.

Methods

We conducted a retrospective single-centre study of consecutive patients referred for redo catheter ablation between January 2024 and January 2025 after undergoing surgical cryoablation (CryoMaze III) during open heart surgery (notably valve replacement or repair). Electroanatomic maps were reviewed to assess left atrial activation patterns, completeness of prior cryomaze lines, and the distribution of residual conduction gaps. Complementary RF lesions were documented and classified according to their anatomical location.

Results

A total of 10 patients (median age 65.8 y ; 50% male) were included. At the time of the redo procedure, the clinical arrhythmia was persistent AF in 4 patients, and left atrial flutter in 5 patients and one patient with right atrial flutter. Mapping revealed incomplete lesion sets in 80% of cases, including 80% with a least 1 VP connected, 70% >=2 VP connected. Roof line was connected in 50%.

The most frequent residual gaps were observed along the left pulmonary veins (40%), the mitral isthmus (40%), atrial roof (50%) and the anterior wall (10%). Additional RF ablation successfully achieved bidirectional block in all treated lines. No major procedural complications occurred. During a median follow-up of 6 months, 90% of patients remained free from arrhythmia recurrence without anti arrhythmic therapy.

Conclusion(s)

In patients with recurrent atrial arrhythmias after surgical cryomaze, electroanatomic mapping frequently identifies incomplete or reconnected lesions, most commonly involving the roof and mitral isthmus lines. Complementary RF ablation allows restoration of durable conduction block with favourable short-term outcomes. These findings highlight the value of detailed cartography to guide tailored redo ablation strategies following surgical maze procedures.Figure 1