Endocardial ablation
All patients underwent an endocardial catheter ablation as second step procedure, after a median time from surgery of 34 [IQR] days. At the time of endocardial ablation, 26 (43%) patients were in sinus rhythm, 27 (45%) in AF and 7 (12%) patients in atypical atrial flutter. No significant differences in rhythm type at endocardial ablation presentation were observed between the two groups.
At the beginning of the endocardial procedure, complete isolation of the posterior LA wall was observed in 22 (36%) patients (n = 10 in BB group, n = 12 in conventional group (P=NS)). Achievement of electrical box isolation required endocardial ablation of the septal aspect of the box in 14/38 patients (36%); of the roof of the box in 12/38 patients (31%); of the lateral aspect of the box in 23/38 patients (60%); of the inferior aspect of the box in 32/38 patients (84%). After the box lesion spontaneous restoration of the sinus rhythm occurred in 2 patients of the Bachmann’s group.
A bidirectional conduction block across the mitral isthmus line was achieved in all patients in the Bachmann’s group compared with 21 patients (70%) in the conventional group (P=0.039). All patients received ablation of the ligament of Marshall, coronary sinus septal inter-caval, cavo-tricuspidal isthmus and superior vena cava isolation. Finally, 3 patients in Bachmann’s group and 2 patients in conventional group received additional ablations for focal atrial arrhythmias.
Total duration of the endocardial ablation was (126±42 min) in BB group vs 143 (±39min) in the CONV group (p = NS). Average hospital stay resulted 2.6 days in BB group vs 2.5 days for the CONV group (p = NS). During endocardial ablation, a spontaneous restoration of sinus rhythm was observed in all patients (n=16) in the BB group versus 5 patients (28%) in the CONV group (p<0.001). Patients in the CONV group still presenting AF (n=9) or atrial flutter (n=4) were successfully converted to sinus rhythm by electrical cardioversion.
After completion of endocardial ablation, incremental atrial pacing was conducted to test arrhythmia inducibility. Sustained atrial arrhythmias (lasting >30 seconds) were observed in 1/30 patients in the Bachmann’s group (3.6%), versus in 19/30 patients (64.4%) in the CONV group (P= 0.0025). No major complications were recorded during the endocardial procedures. Three patients showed modest groin hematoma that non required intervention or transfusion.