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Dokko et al. Vessel Plus 2022;6:37 https://dx.doi.org/10.20517/2574-1209.2021.121 Page 9 of 21

day mortality in patients with pre-operative atrial fibrillation undergoing repair with MitraClip compared to
those without pre-operative atrial fibrillation. However, both groups had a similar rate of stroke at 30-
[89]
day . Although studies conflict on short-term outcomes, many report pre-operative atrial fibrillation as an
[91]
independent predictor of 1-year mortality [86,87] and 3-year mortality with increased MACCE . A
multicenter study with 5-year follow-up also showed an association between atrial fibrillation and reduced
[92]
long-term survival in patients with MitraClip repair but showed no difference in stroke incidence . Most
recently, randomized clinical data from the COAPT trial for Heart Failure Patients with Functional Mitral
Regurgitation trial has shown that history of atrial fibrillation is associated with increased mortality or
hospitalization for heart failure within two years of follow-up compared to patients without a history of
atrial fibrillation. Despite these adverse outcomes, patients with a history of atrial fibrillation still
experienced many benefits, such as reduced rates of mortality and heart failure hospitalization after
MitraClip compared to patients without this intervention .
[93]
Although the association between atrial fibrillation and increased risk of stroke is well-known , recent
[94]
meta-analyses of transcatheter MV repair without ablation procedures have reported no significant
difference in risk of stroke between patients with and without atrial fibrillation. Instead, these studies have
shown increased risk of bleeding in patients with atrial fibrillation, which they suggest may be due to the
administration of oral anticoagulant therapy after MV procedures to prevent stroke [88,90] .

While the impact of pre-operative atrial fibrillation on short-term outcomes of MitraClip intervention is
controversial, it has a clear negative influence on long-term outcomes. Nevertheless, transcatheter
interventions are generally considered last resort options - normally reserved for patients at prohibitive
surgical risk. The pre-operative atrial fibrillation patient population tends to be older and have more
[87]
comorbidities . Thus, these patients may more frequently be poor surgical candidates, necessitating
transcatheter interventions instead. Additional research to mitigate the poor outcomes of transcatheter MV
repair in patients with pre-operative atrial fibrillation is warranted.

Transcatheter ablation
In a recent 3-dimensional echocardiographic study, patients with persistent atrial fibrillation and less than
severe mitral regurgitation were provided radiofrequency catheter ablation and not only maintained sinus
rhythm after 6 months, but also had MV apparatus remodeling with significantly decreased left atrial
[95]
volume, decreased mitral annular diameter, and improved annular contraction . A more recent
retrospective cohort study with a longer mean follow-up time of 20.7 months for patients with paroxysmal
or persistent atrial fibrillation and functional mitral regurgitation showed similar results with decreased left
atrial size in patients who maintained sinus rhythm, but required multiple ablation procedures . This
[96]
finding was in agreement with previously published studies with 5- and 10-year follow-up that reported
success in maintenance of sinus rhythm or decreased rates of permanent atrial fibrillation development with
repeated transcatheter ablation [97,98] .

Comparison of outcomes between mitral valve surgery with concomitant ablation and transcatheter ablation
Both transcatheter and surgical ablation are recommended for the treatment of atrial fibrillation, but few
studies exist comparing the efficacy of transcatheter ablation to mitral valve surgery with concomitant
surgical ablation. Studies on transcatheter ablation have shown that at 12 months, 24%-39% of patients with
MV disease maintained sinus rhythm after a single procedure and 32%-52% after multiple procedures [96,99] .
Studies on concomitant surgical ablation have shown higher rates of success with 63%-90% of patients
maintaining sinus rhythm at 12 months [59,77,100,101] . Similar results were seen in studies directly comparing
concomitant surgical ablation with MV surgery to transcatheter ablation in patients with MV disease. In a