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Dokko et al. Vessel Plus 2022;6:37 https://dx.doi.org/10.20517/2574-1209.2021.121 Page 11 of 21

in the nitric oxide signaling pathway, which has influences on myocardial ion currents, such as the
potassium current. Wnt signaling may promote cardiac fibrosis, which can also contribute to
[116]
arrhythmias .

[117]
Although POAF may be common, it may be a transient condition . The transient nature of POAF
suggests surgical techniques or approaches may be related to the development of this potentially temporary
post-procedural complication. For example, POAF occurs at similar frequencies following transcatheter MV
(MitraClip) procedures , as it does following transcatheter ablation for AF itself , POAF may be related
[119]
[118]
to fluid shifts, oxidative stress, inflammation, catecholamine release, and altered sympathetic and
parasympathetic activity during cardiac surgery [120,121] . Additionally, direct injury to the atria either from
manipulation or incision during surgery may disrupt electrical conduction . This may contribute to
[120]
refractoriness and the formation of reentry wavelets. However, minimizing cardiac manipulation using an
off-pump technique did not lead to a POAF post-CABG decrease .
[103]

POAF is a complex and multifactorial condition. Development of POAF likely depends on both pre-
operative patient-specific factors, such as LA size and genetic alterations, and factors related to surgery.
Understanding the etiology and predictors of POAF development is essential for risk stratification and
treatment decisions in patients undergoing MV repair or replacement. While some risk factors predisposing
to new-onset POAF have been identified for specific cardiac surgery populations, there is a paucity of data
regarding the longer-term impact on MV patients. Future research will be necessary to evaluate the role of
these patient risk characteristics vs. the role of surgery-specific factors, such as surgical “low touch” (i.e.,
reduced manipulation) techniques. Furthermore, to date very little is known about pharmacologic
prophylaxis in this patient population.

Incidence
New-onset POAF is especially common after MV procedures compared to other cardiac procedures .
[8,9]
New-onset POAF has been seen in 24% of patients after surgery for mitral regurgitation and in 39% of
[7]
patients after surgery for mitral stenosis . Overall, the incidence of new-onset POAF in patients undergoing
[8]
[5,6]
MV procedures is between 14%-42% , with approximately 23% of patients developing new-onset POAF
after MV replacement and 15% after MV repair , In patients with transcatheter MV repair using MitraClip,
[5]
the incidence of new-onset POAF was very rare with one study reporting 1.5% .
[122]
Prophylaxis
Prophylactic management of new-onset POAF for patients undergoing MV surgery is primarily through
medical therapy as recommended by the 2014 AHA/ACC/HRS guidelines on the management of atrial
fibrillation (Class IIa, Level A; Class IIb, Level B). Under these guidelines, amiodarone (Class IIa, Level A)
may be recommended prior to surgery or sotalol (Class IIb, Level B) post-surgery when patients are at high
risk of POAF . A recent randomized control trial using one prophylactic dose of intravenous amiodarone
[37]
and magnesium sulfate showed significant differences in post-cardiopulmonary bypass arrhythmia
incidence in patients undergoing surgical MV replacement. This study population included patients with
and without pre-operative atrial fibrillation. At discharge, 30% of patients treated with amiodarone and
magnesium sulfate had atrial fibrillation, compared to 73.3% of patients who did not receive this
[123]
intervention . This finding was in agreement with a previous study of the same framework but using only
a single dose of amiodarone prior to valve replacement .
[124]
As POAF may be in part due to post-surgical inflammation, anti-inflammatory therapies have been
suggested as prophylaxis following cardiac surgery. Several meta-analyses found that prophylactic treatment
with colchicine or dexamethasone decreased POAF after cardiac surgery [125,126] . However, evidence from