Cardiovascular Journal of Africa: Vol 31 No 3 (May/June 2020)

CARDIOVASCULAR JOURNAL OF AFRICA • Volume 31, No 3, May/June 2020

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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.

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%.

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%.

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.

As a single-shot device, cryoballoon ablation markedly simplifies

the ablation procedure and shortens the procedure time.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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