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Page 10 of 21 Dokko et al. Vessel Plus 2022;6:37 https://dx.doi.org/10.20517/2574-1209.2021.121

randomized controlled trial of patients with long-lasting persistent atrial fibrillation and rheumatic heart
[102]
disease, Liu et al. observed that 82% of patients who underwent concomitant surgical ablation with MV
surgery maintained sinus rhythm at 12 months compared to 55% of patients who underwent a single
[103]
procedure of radiofrequency catheter ablation after MV surgery (P < 0.001). More recently, Chen et al.
conducted a retrospective observational study on patients with nonparoxysmal atrial fibrillation and
moderate mitral regurgitation and observed that significantly more patients who underwent concomitant
surgical ablation with MV surgery maintained sinus rhythm at 12 months (69.6%) compared to patients
who underwent a single procedure of radiofrequency catheter ablation (38.8%). At 24 months, concomitant
surgical ablation with MV surgery remained superior with 64.2% of patients maintaining sinus rhythm
compared to 38.3% of patients maintaining sinus rhythm after multiple procedures of radiofrequency
catheter ablations. Patients with radiofrequency catheter ablation were also more likely to have recurrent
atrial tachyarrhythmia . However, complications were also present in concomitant surgical ablation
[103]
patients with a few developing pneumonia and requiring permanent pacemaker implantations, similar to
reports in other studies [75,103] . Considering the risk of permanent pacemaker implantation following
concomitant surgical ablation and the possible need for multiple procedures of transcatheter ablation,
concomitant surgical ablation with MV surgery at present appears to offer better long-term outcomes than
transcatheter ablation for patients with MV disease and pre-operative atrial fibrillation.

POST-OPERATIVE ATRIAL FIBRILLATION IN MITRAL VALVE SURGERY
Etiology
New-onset post-operative atrial fibrillation (POAF) is a condition that is neither well understood nor
defined, particularly in patients undergoing MV procedures. POAF is frequently grouped with perioperative
atrial fibrillation due to unclear consensus on the timing of POAF [104-107] . Mitral stenosis and LAE are
identified risk factors for the development of atrial fibrillation after cardiac surgery . POAF following MV
[108]
replacement occurs more often in rheumatic than non-rheumatic mitral stenosis . Age and concomitant
[109]
aortic or tricuspid valve surgery have been identified as important risk factors associated with POAF
[5]
following MV surgery .
LA size prior to MV surgery for mitral regurgitation has been associated with risk of early POAF [7,110] , while
LA diameter and pressure half time are risk factors for late POAF, occurring after hospital discharge . LA
[111]
volume index after MV surgery also independently predicts the development of POAF . In a cohort of
[112]
patients with rheumatic MV disease undergoing MV replacement, transmitral A waves as measured on
echocardiogram were predictive of POAF occurring or lasting 1 year after surgery .
[113]

Electrocardiogram findings may yield insights into the etiology of this condition as well. Mitral
regurgitation patients undergoing percutaneous MV repair via MitraClip had several changes in
electrocardiogram findings after surgery, including decreased P wave duration, P wave amplitude, and PR
[114]
interval, which suggest alterations in atrial conduction patterns . Similarly, in percutaneous MV
commissurotomy for rheumatic mitral stenosis, atrial effective refractory periods (AERP) increased and
AERP dispersion decreased after resolution of atrial stretch . These changes in conduction may be of
[115]
significance in delaying or preventing the development of atrial fibrillation.

Genetic factors may be involved in the development of POAF, as demonstrated by RNA sequencing of
tissue samples from the LA collected just prior to MV surgery . Expression of genes involved in potassium
[116]
current-modulated resting membrane potential, metabolism of cyclic GMP, and wingless integrated (Wnt)
signaling varied between patients with and without POAF. Alterations in resting membrane potential due to
changes in potassium currents provide a feasible explanation for arrhythmogenesis. Cyclic GMP is involved