Introduction: Peri-mitral atrial flutter (PMFL) remains challenging target of catheter ablation. Success rates of achieving conduction block of mitral isthmus is not satisfactory even in the recent clinical studies.
Purpose: The aim of this study was to evaluate the efficacy of ablation at the left atrial anterior wall for the treatment of PMFL as an alternative to the mitral isthmus ablation.
Methods: We studied twenty-seven consecutive patients (16 males, 65±12 y.o.) with PMFL (clinically macro-reentrant atrial tachycardia) undergoing catheter ablation. We retrospectively analyzed the clinical and electrophysiologic properties. Therapeutic outcomes after ablation were compared between targeting anterior wall and mitral isthmus.
Results: Eleven patients (40%) had underlying heart diseases (valvular heart disease 5 and cardiomyopathy 6). Diameter of left atrium was 47±6mm. Thirteen patients had previous ablation for atrial fibrillation among which 9 had continuous fractionated atrial electrogram (CFAE)-guided ablations. Ablation for PMF was performed at the mitral isthmus (MI) in 16 patients (MI group) and at the left atrial anterior wall in 11 (AL group). An anterior line was created when a regional scar or low voltage area was observed at the anterior wall. According to voltage maps, anterior lines were created between mitral annulus and the pulmonary veins (PV) (right superior PV 9, left superior PV 2). Acute procedural success defined as conduction blockade was achieved among 13 patients (81%) in the MI group, and 9 patients (82%) in the AL group (p=0.97). Mitral isthmus ablation required epicardial ablation from the coronary sinus in 8 patients (62%). Clinical success defined as freedom from atrial tachycardia recurrence was achieved in 24 patients (88.9% in total) at the 1-yr follow-up.
Conclusion: The left atrial anterior line can be an useful alternative to the mitral isthmus line for treating PMFL. This strategy may be especially feasible in patients with degeneration or scar at the anterior wall or with anatomical difficulties at the mitral isthmus such as long distance. An electro-anatomical map may help selecting an appropriate therapeutic target in PMFL ablation in a patients basis.