Commentary to: ‘Comparing Mid-Term Outcomes of Cox-Maze
Procedure and Pulmonary Vein Isolation for Atrial Fibrillation After
Concomitant Mitral Valve Surgery: A Systematic Review’
Marco Moscarelli1, Khalil Fattouch1
1 Dept of Cardiovascular Surgery, Maria Eleonora
Hospital, GVM Care&Research, Palermo, Italy
Corresponding author:
Marco Moscarelli
GVM Care & Research, Eleonora Hospital
Via Regione Siciliana
Palermo (PA) 90135, Italy
Tel: +39 091 698 1111
E-mail: m.moscarelli@imperial.ac.uk
Funding : this research received no specific funding.
Conflict of interest : none.
In 1987 Dr James Cox described the first surgical technique to treat
atrial fibrillation (AF). This procedure was based on a standardized
‘cut-and-sew’ approach with the aim to convey the native sinus impulse
to both atria and atrioventricular node while suppressing re-entrant
circuits (1). This original version (named ‘Cox-Maze’) was affected by
high rate of post-operative pacemaker implantation. Further versions
were introduced to improve the outcomes, finally resulting in the
Cox-Maze III. Prasad and Colleagues examined the long-term performance
of Cox-Maze III either as a lone operation or as concomitant procedure
and reported excellent freedom from atrial fibrillation at distance (2).
In order to achieve an even more simple and less invasive approach, in
2002, Damiano and colleagues replaced the majority of the incisions of
the Cox-Maze III with sets of bipolar radio-frequency (RF) and
cryothermal ablations lines and finally this approach was named Cox-Maze
IV. This simplified technique led to a significant increase in the
number of operations performed annually for AF (3).
Pulmonary vein isolation (PVI) is however, a more popular approach for
treating AF given its simplicity and rapidity. In contrast to the
bi-atrial maze lesion set that requires right and left atriotomies, the
PVI involves the creation of circumferential ablation lesions around the
pulmonary veins. In addition, it can be performed also without the need
of cardiopulmonary bypass (4).
PVI technique is directed mainly at the triggers of AF, whereas maze
lesions ablations lines aim to interrupts pathways needed for
maintenance of the arrhythmia (4).
Surgical ablation concomitant to mitral valve surgery has been shown to
be associated with improved early outcomes as such as reduced early
mortality and post-operative stroke (5).
Data on the comparative effectiveness of the Cox-Maze vs. PVI during
concomitant mitral valve surgery are very limited.
To address this gap in literature, Sef and Colleagues conducted a
systematic review and meta-analysis to compare mid-term mortality (after
12 months follow-up) and recurrence of AF after concomitant Cox-Maze and
PVI in patients with AF undergoing mitral valve surgery (6). Secondary
outcomes included: cardiopulmonary bypass and cross clamp time, rate of
mitral valve repair and duration of preoperative AF.
After literature search, three randomized controlled trials (RCT) and
three non-randomized studies of intervention (NRSI) were included with
790 patients in total (532 concomitant Cox-Maze and 258 PVI 45 during
mitral valve surgery surgery).
There was no difference in terms of mortality after 12-months between
the two procedures. Nevertheless, considering the limited number of
enrolled patients, meta-analysis resulted in wide confidence interval,
hence substantial uncertainty remains.
With regard to AF recurrence, most of the studies reported that Cox-Maze
was associated to higher freedom form arrythmia at 12-months follow-up
when compared to PVI. On this basis, they concluded that concomitant
Cox-Maze in patients undergoing mitral valve surgery was associated with
a strong tendency of better mid-term freedom from AF.
Authors have to be commended for this interesting quantitative synthesis
that compare Cox-Maze with PVI during mitral valve surgery. First and
foremost, they are shedding light to the need and benefits of addressing
AF at the time of surgery.
It is important to underscore that nowadays many mitral procedures are
carried out in the minimally invasive way, hence the Cox-Maze approach
may be not entirely feasible in such context.
It is also noticeable that evidences from literature are scares, with
many underpowered studies and with high heterogeneity. As such certain
ambiguity remains and more studies are needed to established what
procedure is more effective.
Although the Cox-Maze may be linked with higher success rate, in an era
of less invasive, hybrid and wire skilled techniques, more practical,
fast and reproducible approaches are probably to be preferred.