Australian Doctor 12th July Issue 2024 | Page 37

Figure 2 . Treatment algorithm for symptomatic AF .

Reproduced with permission from Oxford University Press , G Hindricks et al , European Heart Journal , 2021 , 42 / 5 , 373-498 . 3

Box 1 : Recommended strategies to reduce AF progression and recurrence 3-5

puncture of the interatrial septum . Femoral vein access is obtained and transseptal puncture is performed .

Complications

High-volume centres for AF ablation have reported an acute complica-

• Blood pressure control ( class I recommendation )

• Weight loss in obese patients ( class IIa recommendation )

• Avoidance of excessive alcohol ( class IIa recommendation )

• Increased physical activity ( class IIa recommendation )

• Screening and treatment of obstructive sleep apnoea ( class IIb recommendation )

fraction , longer six-minute walk distance

and quality of life . 15

Given the superiority of catheter

ablation in maintaining sinus rhythm and improving arrhythmia-related symptoms , the 2020 European Soci-

A mapping catheter is then used , together with a 3D electro-anatomical mapping system , to reconstruct the left atrium and pulmonary veins and guide navigation of catheters to deliver circumferential ablation around the pulmonary veins , thus preventing propagation of AF triggering ectopic beats ( see figure 3 , video 1 ). 16

Conventionally , thermal ablation has been used to achieve pulmonary vein isolation . This has been applied either in the form of radiofrequency electrical current energy ( heat ) or cryoballoon ( cold ).

However , the technology for both mapping and ablation of AF is rapidly evolving , with many new ablation devices entering the mar-

Figure 3 . 3D electroanatomical map generated to guide catheter ablation .

Left atrial voltage mapping during AF ablation and radiofrequency ablation lesions ( red dots ) delivered to achieve pulmonary vein isolation . Purple represents electrogram voltage > 0.5mV ( considered normal myocardium ) and red < 0.05mV ( consistent with dense scar or pulmonary vein issue ). Note the myocardial muscle sleeves extending into the pulmonary veins .

LSPV = left superior pulmonary vein . LIPV = left inferior pulmonary vein . RSPV = right superior pulmonary vein . RIPV = right inferior pulmonary vein

tion rate of < 1-6 %. Bleeding complications at the vascular access site are the most common ( 1.31 %) followed by pericardial effusion ( 0.78 %). Less common complications include ischaemic stroke ( 0.17 %), pulmonary vein stenosis ( 0.07 %), phrenic nerve injury ( 0.08 %), and atrioesophageal fistula ( 0.04 %). Fortunately , the incidence of these acute complications has decreased significantly over the years . With increased technical expertise and improved technology , the sum risk of serious complications is now around 1.9 %, including about a one in 2000 risk of death . 29

Conclusion

Catheter ablation is a well-established

ety of Cardiology AF management

ket . Of particular interest is pulsed

may occur due to pericardial inflam-

Registry data show freedom from AF

and increasingly utilised treatment

guidelines have now positioned it as a

field ablation ( PFA ), a non-thermal

mation , and may not reflect true

at one year of 81.6 % for patients with

strategy for symptomatic AF . There

first-line therapy for symptomatic AF ,

modality whereby ultrarapid high

relapse . Symptomatic pericarditis

paroxysmal AF and 71.5 % for persistent

is increasing evidence demonstrat-

depending on patient preference . Addi-

voltage electrical fields are applied

may be managed with colchicine ,

AF , after treatment with one of the reg-

ing the superiority of catheter ablation

tionally , catheter ablation is now a class

to target tissue , to create pores in

which is usually quite effective as

istered proprietary PFA systems . 18

over anti-arrhythmic therapy for AF

I recommendation for patients with

the phospholipid membrane , lead-

monotherapy .

Recurrence of AF after pulmonary

control and it is now more likely to be

concomitant heart failure with reduced

ing to leakage of intracellular con-

According to Austroads , it is advisa-

vein isolation predominantly occurs as

offered as a first-line therapy option .

ejection fraction ( see figure 2 ). 3

tent and eventual cell death . The

ble to not drive for one week post-abla-

a result of reconnection of the pulmo-

Despite catheter ablation being a com-

Catheter ablation : techniques and technology

Pulmonary vein ectopy and tachycardia

are commonly responsible for initiating AF . The cornerstone of catheter

advantage of PFA is its ability to achieve efficient acute isolation of the pulmonary veins and its selectivity for myocardial tissue , potentially reducing the risk of collateral injury to vital surrounding struc-

tion on a private standard licence and four weeks for commercial licences .

Success rate

The success rate depends on the type

of AF ( paroxysmal , persistent or long-

nary veins due to failure of transmural ablation . This may necessitate a repeat ablation procedure . Newer technology and approaches may result in more durable results . 20 , 21 In patients with persistent AF , pulmonary vein isola-

plex procedure , major complications are relatively uncommon in large volume centres . Emerging technologies and procedural strategies continue to improve the efficacy and safety of catheter ablation therapy for AF .

ablation therapy is to achieve electrical isolation of the pulmonary veins , with complete electrical disconnec-

tures , including the phrenic nerve and oesophagus . Randomised clinical trials and a multicentre real-

standing persistent ), and presence of structural heart disease and comorbidities . One meta-analysis showed

tion alone may not be sufficient . These patients tend to have more advanced left atrial disease and regions of scar .

References on request from kate . kelso @ adg . com . au

tion of the pulmonary veins from the left atrium . 2 In Australia , the procedure is typically performed under general anaesthesia . The patient is fully anticoagulated before the procedure , using either a direct oral anticoagulant , or warfarin targeting an INR of 2-3 . Intraprocedural heparin is also given to minimise thrombus formation and stroke risk . At the time of the procedure , a transoesophageal echocardiogram is performed to exclude left atrial append-

world registry has shown that PFA has an excellent safety profile and

18 , 19 efficacy .

Post-procedural considerations

In the authors ’ practice , patients are

generally asked to lie flat for four hours post-procedure , and to avoid strenuous activity for one week to prevent bleeding from the groin access site .

In the first three months follow-

a 12-month success rate of 66.6 % for patients with paroxysmal AF , after a single pulmonary vein isolation procedure using radiofrequency ablation . For patients with persistent AF , catheter ablation has a lower success rate of 51.9 % at 12 months , which reflects extrapulmonary mechanisms that perpetuate AF . 21 The success rate using cryoballoon is similar to radiofrequency , with multiple meta-analyses showing freedom from AF is compa-

They may also have AF triggers outside the pulmonary veins , such as the superior vena cava , coronary sinus , crista terminalis , posterior left atrial wall and left atrial appendage . 22 , 23 Left atrial scar , either from disease or due to prior ablation , can give rise to atypical atrial flutters which can be targeted effectively with ablation . 24 Further ablation lines to isolate the posterior left atrium , or even the left atrial appendage in select patients , may be

Online resources

• Video footage of left atrial voltage mapping during AF ablation , and left atrial flutter , can be viewed in the online version of this article , at : www . ausdoc . com . au / therapy-update / a-gp-guideto-catheter-ablation-foratrial-fibrillation

age thrombus , and to guide transseptal

ing catheter ablation , recurrent AF

rable between these two methods . 26-28

beneficial . 25