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Dokko et al. Vessel Plus 2022;6:37 https://dx.doi.org/10.20517/2574-1209.2021.121 Page 5 of 21

Few studies have examined the use of concomitant ablation for patients with pre-operative atrial fibrillation
undergoing isolated MV surgery [17,74] . Further detailed in Section 1.4.2, concomitant ablation has been
associated with reduced thromboembolic risk and atrial fibrillation recurrence [58,59] . In the few studies that
have been reported on isolated MV surgery, pre-operative atrial fibrillation was associated with increased
risk of stroke and bleeding complications. Bando et al. conducted a multicenter retrospective study
[17]
comparing outcomes in three groups of patients: patients in sinus rhythm who underwent isolated mitral
valvuloplasty for mitral regurgitation, patients with pre-operative atrial fibrillation who underwent isolated
mitral valvuloplasty, and patients with pre-operative atrial fibrillation who underwent concomitant ablation
with mitral valvuloplasty. They observed that of the three groups, survival and eight-year freedom from
stroke were worst for patients with pre-operative atrial fibrillation who underwent isolated mitral
[17]
[74]
valvuloplasty . A study by Ngaage et al. comparing outcomes between patients with pre-operative atrial
fibrillation and patients in sinus rhythm after isolated repair for MV regurgitation reported similar results
with higher mortality and reduced freedom from cardiac death in patients with pre-operative atrial
fibrillation compared to patients in sinus rhythm. Most importantly, pre-operative atrial fibrillation was
reported to be an independent risk factor for adverse cardiac events and stroke .
[74]
To summarize, Tables 1 and 2 list several multivariate models predicting short- and long-term post-
procedural morbidity and mortality where pre-operative atrial fibrillation was a model-eligible variable.
Based on this evaluation of MV multivariable models’, it is striking that pre-operative atrial fibrillation
appears as an important risk factor predictive of adverse MV surgical outcomes; thus, additional research
appears warranted to identify the atrial fibrillation-related management strategies to improve the future
quality of MVR patient care.

Mitral valve surgery with concomitant surgical ablation
Concomitant surgical ablation therapy has been associated with decreased adverse outcomes in patients
with pre-operative atrial fibrillation undergoing MV procedures. Due to increased long-term mortality risk
with pre-operative atrial fibrillation, concomitant surgical ablation is recommended in patients undergoing
MV procedures to restore sinus rhythm [2,54-58] . Although concomitant surgical ablation with MV surgery has
been associated with increased risk for permanent pacemaker implantation compared to MV surgery
[55]
[75]
alone , several studies have shown reduced incidence of late stroke , improved sinus rhythm [56,57] , and
lower risk of mortality in patients who underwent concomitant surgical ablation [58,76] .
In a randomized multi-center clinical trial following patients with persistent or long-term persistent atrial
fibrillation for 1 year, patients who underwent MV surgery and concomitant ablation via pulmonary-vein
isolation or biatrial Maze procedure demonstrated greater freedom from atrial fibrillation at 6 months and
12 months than patients who only received medical therapy (63.2% vs. 29.4%). However, 1-year mortality
and 1-year risk of MACCE were similar between both groups, with more frequent permanent pacemaker
[59]
implantation in patients who received concomitant ablation (21.5% vs. 8.1%) . A more recent study with
longer follow-up demonstrated similar benefits in patients with pre-operative atrial fibrillation who
underwent concomitant surgical ablation via Cox Maze III/IV using radiofrequency ablation, cryoablation,
or both during only MV surgery. This sample of patients had freedom from atrial fibrillation without the
need for antiarrhythmics at rates of 85%, 79% and 64% at 1, 5, and 7 years, respectively. Only 2% of patients
experienced embolic stroke and 9% required pacemaker placement. Atrial fibrillation recurrence was
associated with longer duration of pre-operative atrial fibrillation and the surgeon’s experience with
ablation . Although pacemaker implantation is considered a negative outcome of ablation procedures, it
[77]
may be associated with less morbidity than previously thought. A prospective study of pacemaker
implantation following Cox Maze procedures for AF found that pacemakers are actually implanted at lower