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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 31, No 3, May/June 2020
156
AFRICA
demonstrated that patients with persistent AF for less than 60
days who received early DCC had a significant reduction in AF
recurrence risk, while in those with persistent AF for more than
60 days, there was no benefit of early DCC.
29
Conversion of AF to sinus rhythm is associated with an
increased risk of stroke. Two strategies of anticoagulation are
available for reducing thromboembolic risk. The first is warfarin
for three weeks prior to DCC and continues for four weeks after
cardioversion. The second is transoesophageal echocardiography
and combination treatment with an anticoagulant using heparin,
enoxaparin or one of the NOACs immediately before DCC
and followed by warfarin or NOACs for four weeks after
cardioversion.
Radiofrequency catheter ablation (RFCA)
An important mechanism of AF is abnormal electrical activity
surrounding the vestibule of the pulmonary veins (PVs).
RFCA is primarily a treatment outcome achieved through
isolation of the PVs. A long-term follow up showed the rate
of freedom from atrial arrhythmia with a single procedure was
54.1% in paroxysmal AF patients and 41.8% in patients with
non-paroxysmal AF. With multiple procedures, the long-term
success rate improved to 79.8%.
30
Collective data from a number
of randomised clinical trials had demonstrated the superiority
of RFCA over drug therapies in maintaining sinus rhythm,
reducing cardiovascular events, and improving quality of life.
31,32
RFCA is highly recommended for symptomatic paroxysmal
AF patients aiming to prevent recurrent AF and improve
symptoms, especially when anti-arrhythmic drug therapy
is unsuccessful. It is also a reasonable alternative for those
symptomatic AF patients with heart failure, low ejection fraction
or AF-related bradycardia.
A worldwide survey of 85 institutions indicated a 4.5% rate
of major complications of RFCA. Specifically, the rate of
procedure-related deaths was 0.15%, stroke or transient ischaemic
attack were 0.94%, cardiac tamponade was 1.31% and atrial–
oesophageal fistula was 0.04%.
33
RFCA is a therapy that highly
depends on clinicians’ experience and skill, which are related
to the success rate and incidence of complications. Individual
characteristics, patient preferences, as well as experience and
skill of the clinician should be taken into consideration before
making a decision.
Cryoballoon ablation
Catheter ablation using technical requirements with three-
dimensional mapping systems with a point-by-point ablation
strategy is time-consuming, and clinical outcomes and
complications depend on the operator’s experience and skill. To
overcome these limitations, cryoballoon ablation was developed.
34
As a single-shot device, cryoballoon ablation markedly simplifies
the ablation procedure and shortens the procedure time.
35
Cryoablation systems work by delivering liquid nitrous oxide
under pressure through the catheter to its tip or within the
balloon, where it changes to gas, resulting in cooling and damage
to the surrounding tissue, thus resulting in a reduction in the
risk of AF.
36
A first-generation cryoballoon (CB-1) was released
in 2010 and the more developed second-generation cryoballoon
(CB-2) was developed in 2012. The one-year success rate of CB-2
was improved from CB-1, and the complication rates decreased
in the former.
36
Data from recent studies have demonstrated the clinical
benefit of cryoballoon ablation for paroxysmal AF patients.
35,37
It is a promising, effective and safe alternative technique for
paroxysmal AF patients. However, cryoablation is specially
designed for dissection of the pulmonary artery. Pulmonary vein
isolation is the cornerstone of cryoablation and other treatments
should be considered for AF that does not originate in the
pulmonary veins.
Left atrial appendage closure (LAAC)
Studies have shown that 91% of strokes occur in the left atrial
appendage of non-rheumatic AF patients and 57% in rheumatic
AF patients.
38
This understanding has prompted the development
of novel percutaneous strategies for LAAC as an alternative to
anticoagulation therapy for AF patients. Briefly, LAAC is
recommended for elderly patients and those who can tolerate
short-term anticoagulation but are not optimal candidates for
long-term anticoagulation.
39
A meta-analysis that compared LAAC with warfarin for
stroke prevention in AF included 2 406 patients with a mean
follow up of 2.69 years. It found that Watchman LAAC had
significantly fewer haemorrhagic strokes and better clinical
outcomes compared with warfarin therapy.
40
A network meta-
analysis found that Watchman LAAC and NOAC therapy were
both superior to warfarin for preventing haemorrhagic strokes,
and that there were no significant differences in clinical outcomes
between Watchman LAAC and NOACs.
41
According to the latest
ESC guidelines, LAAC is a good alternative for AF patients with
contra-indications to OAC (Class IIB, level of evidence B).
Surgical management
The Cox maze I procedure, introduced by James Cox in 1987,
interrupted the aberrant re-entrant circuits in the atrium by
‘cutting and sewing’. After iterative improvements, Cox maze I
was modified into the Coxmaze III procedure.
42
But the Coxmaze
III did not gain widespread acceptance due to its complexity and
technical demand. It is mainly used in AF patients undergoing
open-heart surgical procedures. Development in technology led
to shortening and simplification of the operation to the Cox
maze IV, which utilises new ablation technologies to replace
the ‘cut-and-sew’ technique, and has decreased morbidity and
mortality rates.
43
Cox maze IV is currently the gold-standard
surgical treatment for AF, with a 93% freedom from AF at one
year, and a 78% freedom from AF at five years.
44
The totally thoracoscopic maze procedure (TT-maze) was
developed in 2003. It was a minimally invasive alternative for
treating AF with limited complications and high success rates.
45
Future studies are needed to determine whether the high success
rates after TT-maze are stable over time.
Conclusions
Management of AF has evolved greatly in the past few years and
there have been substantial advances and developments, which
help clinicians to deliver better care to AF patients (Fig. 1).
Treatment of AF is an individual therapy and the characteristics