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Before cardiac ablation Cardiac ablation for AF After cardiac ablation

Left atrium Left atrium Mapping catheter Left atrium

Normal mitral valve

Mitral stenosis

Closed Closed

Mitral valve

Open Open

Figure 8 . Mitral stenosis .

whereas apixaban and rivaroxaban have shared renal and hepatic excretion . Current TGA product information allows for rivaroxaban use at a creatinine clearance ( CrCl ) of 15mL / min ; by comparison , apixaban is listed as contraindicated in those with a CrCl of less than 25mL / min . 33 Retrospective data suggest apixaban may be safer and more effective than warfarin in non-valvular AF in patients with a CrCl of less than 25 , and even in those with end-stage kidney disease on dialysis . However , the use of apixaban at these lower levels of CrCl is uncommon , is not recommended by any society guidelines , and has not been validated by any published RCTs . 34

Left atrial appendage interventions

Given the vast majority of cardioembolic strokes due to AF are thought to be due to thrombi that form in the LAA , interventions to occlude or exclude the LAA have been a recent source of interest . The most common intervention is percutaneous LAA occlusion ( see figure 9 ), although surgical occlusion and exclusion are also available . Two RCTs have examined percutaneous LAA closure , both comparing the Watchman LAA closure device to warfarin therapy .

Table 2 . CHA 2

DS 2

-VA score and stroke risk Score Points Definition

H 1 History of Hypertension , whether or not blood pressure is currently elevated

A 2

2 Aged 75 or older D 1 Diabetes

S 2

2 History of prior Stroke , TIA or systemic thromboembolism

A 1 Aged 65-74 HFrEF = heart failure with reduced ejection fraction ; HFpEF = heart failure with preserved ejection fraction . Source : Brieger D et al 2018 12

Table 3 . NOAC dose

Dabigatran Rivaroxaban Apixaban Standard dose 150mg bd 20mg daily 5mg bd Reduced dose 110mg bd 15mg daily 2.5mg bd

Dose reduction criteria

Dabigatran 110mg bd for :

• Age 80 and older

• Concomitant use of verapamil , or

• Increased bleeding risk

CrCl 15-49mL / min At least two of three criteria :

• Age 80 and older

• Body weight 60kg or less

• Serum creatinine 133 µ mol / L or greater

Source : Hindricks G at al 2021 11

Both demonstrated LAA closure to be non-inferior to warfarin with regard to risk of ischaemic stroke and major bleeding , with 3.6-4.9 % of patients experiencing a major adverse event from device implantation within 30 days of intervention . 35 , 36 There are no RCTs that have compared LAA closure to NOAC use . There are also no studies that have directly compared LAA closure with placebo in those where anticoagulation is contraindicated ; however , it is widely accepted that percutaneous LAA closure may be of benefit in this group .

Risk factor management

Treating the risk factors for AF supports prevention , reduces AF burden , and prevents associated mortality and morbidity . The five key risk factors to manage are obesity , OSA , alcohol intake , exercise and hypertension .

OBESITY AND OBSTRUCTIVE SLEEP APNOEA Risk of AF increases progressively with higher BMIs . 37 Animal-based studies have demonstrated that chronic obesity is associated with increased fat in the epicardial tissue lining the outside of the heart , and infiltration of this fat into atrial