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Page 4 of 21 Dokko et al. Vessel Plus 2022;6:37 https://dx.doi.org/10.20517/2574-1209.2021.121

atrial fibrillation and can be performed through a cut-and-sew-technique, radiofrequency ablation, or
cryoablation [53,59,60] . The outcomes of concomitant surgical ablation for patients with pre-operative atrial
fibrillation are detailed in Sections 1.4.2. and 1.4.6.

A subset of patients may have symptomatic pre-operative atrial fibrillation unresponsive to medical
management with low severity of MV disease that does not warrant MV surgery. For these patients who are
not candidates for MV surgery or who are at high risk for concomitant surgical ablation, transcatheter
A
a b l a t i o n , a m o r e m i n i m a l l y i n v a s i v e a p p r o a c h , i s available . c c o r d i n g t o t h e 2 0 1 7
[61]
HRS/EHRA/ECAS/APHRS/SOLAECE Expert Consensus Statement on Catheter and Surgical Ablation of
Atrial Fibrillation and 2014 AHA/ACC/HRS guidelines, transcatheter ablation is recommended for
paroxysmal atrial fibrillation when Class I or Class III antiarrhythmic drugs are ineffective (Class I, Level
A) [37,61] . Pulmonary vein isolation is considered to be the key element of transcatheter ablation; however,
recent literature has demonstrated that it may not be enough, especially in cases of persistent AF. A recent
meta-analysis has demonstrated that left atrial appendage ablation, in addition to pulmonary vein isolation,
had decreased recurrence of AF when compared to patients who received pulmonary vein isolation ablation
[62]
alone . In a propensity score-matched study of persistent AF with a mean follow-up of 30.5 months,
patients who received both left atrial appendage and pulmonary vein isolation (75.7%) had significantly
greater freedom from atrial tachyarrhythmia with no difference in cerebrovascular events or all-cause
mortality compared to patients who received only pulmonary vein isolation (61.6%). Furthermore,
[63]
pulmonary vein isolation alone was a significant predictor of recurrent atrial tachyarrhythmia . As such,
transcatheter ablation now often involves a combination of pulmonary vein isolation and ablation of the left
atrial appendage. The outcomes of left atrial appendage exclusion and transcatheter ablation for pre-
operative atrial fibrillation are detailed in Sections 1.4.3 and 1.4.5-1.4.6, respectively.

When medical therapy is insufficient to address persistent or worsening symptoms of AF for MV patients,
as a last option AV nodal ablation may be considered (Class IIa, Level B) by AHA/ACC/HRS
guidelines [37,53,64] . Though successful in alleviating symptoms and improving quality of life, AV nodal
ablation is often performed only when necessary, such as in patients for whom both medical therapy and
catheter ablation are insufficient in addressing refractory, symptomatic and permanent AF and present with
LVEF < 35% and NYHA functional class I or II, due to it requiring the patient to live with a permanent
pacemaker and possible complications of sudden cardiac death and heart failure [65-71] . Permanent
pacemakers may further worsen left ventricular function in patients with AF, increasing the likelihood of
heart failure [68,71] .

Outcomes
Mitral valve surgery
Although studies differ on the impact of pre-operative atrial fibrillation on early mortality, studies with 5- to
10-year follow-up have shown pre-operative atrial fibrillation to be an independent predictor of increased
long-term mortality and other long-term adverse outcomes [2,4,72] . Furthermore, a study including 382
patients found that survival at 15 years following surgery was significantly lower in those with atrial
fibrillation (59.9%) compared to those without (86.5%). Patients with atrial fibrillation and/or pulmonary
hypertension also had reduced freedom from major adverse cardiac and cerebrovascular events (52.7% vs.
74.5%) and a decreasing trend in freedom from recurrent mitral regurgitation (65.1% vs. 87.0%), suggesting
decreased effectiveness of MV repair in that group . These studies imply that atrial fibrillation, although
[73]
often an independent variable for the outcome, may be a surrogate of worse myocardial conditions (e.g.,
heart failure).