Patients (pts) with atrial fibrillation (AF) and significant mitral valve regurgitation are supposed to have a poor outcome of catheter ablation (CA) of AF and ablation is reluctantly performed in this pts group in the absence of indication for heart surgery. On the other side also left atrial fibrosis have been linked to poor AF ablation outcome. Therefore, we analyzed the occurrence and the role of atrial fibrosis detected by low voltage areas in patients undergoing AF ablation at our center despite significant mitral regurgitation.
Seventy-seven pts with moderate (grade II: 82%) and severe (grade II-III und III: 18%) mitral valve regurgitation without planed heart surgery at the time point of ablation and with symptomatic AF (paroxysmal: 36%, persistent: 64%) underwent CA of AF after left atrial high density voltage mapping with multi-microelectrode catheters at our center in the years 2016-2020. Before CA all pts underwent a TEE for severity assessment of mitral regurgitation and significant mitral valve regurgitation was defined by vena contracta width of >0.4 cm. Mean age of this pts group was 68±9 years, mean left atrial diameter 43±5 mm and left atrial area 25±6 cm2. In all pts pulmonary vein isolation (PVI) was performed. Additional substrate ablation (mainly left atrial linear ablation) was performed in pts with inducible atrial flutter, or in patients with inducible AF after PVI and low voltage areas >20% or in pts with low voltage areas >40%.
Left atrial low voltage areas accounted for 33±29% of the atrial surface in all pts. No or modest low voltage areas (<10%) were found in 31% of pts, moderate low voltage areas (<20%) were found in 18% of pts, and severe low voltage areas were present in 51% of pts. Beyond PVI in 40% of pts additional fibrosis guided left linear ablation line were performed, in 25 pts a roof line, in 21 pts an anterior mitral line and in 4 pts box isolation of the four PVs. Furthermore, 20 pts underwent cavotricuspidal isthmus ablation due to documented or inducible typical atrial flutter. The overall one year freedom of atrial tachyarrhythmias without antiarrhythmics accounted for 49% (single procedure success). Procedure success in pts with low or modest low voltage areas was 78%, in patients with moderate low voltage areas was 58% and with severe low voltage areas was 41%.
Left atrial fibrosis as estimated by low voltage areas is more frequent in patients with mitral regurgitation than in other pts cohorts so far reported. Low voltage areas quantified by high density 3D mapping are a strong predictor of AF ablation success rate even in patients with significant mitral regurgitation. Although the outcome of AF ablation in pts with significant mitral regurgitation has been reported to be low, AF ablation seems to be highly effective in pts with no or modest left atrial fibrosis accounting for one third of such pts. With left linear ablation in addition to PVI a moderate success rate could be achieve with a single procedure even in pts with severe atrial fibrosis and significant mitral regurgitation.