ausdoc . |
com . au |
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X OCTO- MONTH library at www . ausdoc . com . au / therapy-update
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2022
BER
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Drug |
Indication |
Adverse effects |
Precautions and |
contraindications |
Digoxin |
Rate control |
Generally well tolerated Overdose results in severe bradycardia , ventricular arrhythmias , nausea , abdominal pain |
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Amiodarone
Sotalol
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Rhythm control ( occasionally also rate control )
Rhythm control
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Extensive side effect profile including acute and delayed pneumonitis , liver injury , thyroid dysfunction , skin discolouration , prolonged QTc
Prolonged QTc and ventricular arrhythmias , symptomatic hypotension / bradycardia
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Limit prolonged use in younger patients who are at greater risk of cumulative toxicity Monitor for drug-drug interactions ( eg , increases in warfarin and digoxin levels ) Minimise maintenance dose Check liver and thyroid function at baseline and six monthly
Close monitoring of QTc interval Monitor for symptoms of postural hypotension
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Figure 5 . Cardiac event recorder as seen on chest X-ray . The event recorder is implanted too high cranially . |
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Flecainide |
Rhythm control |
Unstable fast ventricular rhythms in the setting of atrial flutter Increased risk of death in those with a history of MI or abnormal left ventricular structure / function |
Monitor QRS interval Avoid in those with CAD , moderate or greater left ventricular hypertrophy , or reduced left ventricular ejection fraction Always use in combination with an AV nodal blocking agent ( eg , a beta blocker or non-dihydropyridine CCB ) Do not use in the cardioversion of atrial flutter |
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the source of ectopic atrial beats that may trigger AF ( see figure 7 ). Other parts of the atria are also frequently ablated in an attempt to increase the success of this procedure . While ablation carries the risk of damage to nearby structures ( which can lead to cardiac perforation , complete heart block or oesophageal injury ), it potentially avoids the need for oral antiarrhythmics and may reduce hospitalisations in selected patients with heart failure associated with left ventricular systolic dysfunction . 25
Stroke prevention
While AF is associated with a fivefold
increased risk of stroke , this risk is not equal in all subgroups with AF . 26 In addition , interventions to prevent stroke , such as anticoagulation , are associated with adverse effects , for example , bleeding . Clinical calculators are available to stratify patients with AF according to their risk of stroke ; this will identify those in whom anticoagulation likely outweighs the risk of harm from therapy . The score recommended by the Cardiac Society of Australia and New Zealand is the CHA 2
DS 2
-VA score ( see table 2 ), which is the non-gender specific version of the CHA 2
DS 2
-VASc score . 12 Anticoagulation is recommended in those with a CHA 2
DS 2
-VA score of 2 or greater and is considered in those with a CHA 2
DS 2
-VA score of 1
( see table 2 ). Other clinical calculators , such as the HAS-BLED score , will determine
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the risk of bleeding , however they do not provide a cut-off above which anticoagulation is contraindicated . This is partly because higher scores on such clinical calculators are associated with an increased risk of both bleeding and cardioembolic stroke . 12 , 27 For example , three of the seven HAS-BLED score components ( hypertension , previous stroke and older age ) are also risk factors for cardioembolic stroke , which are incorporated into the CHA 2
DS 2
-VA score . Thus , higher HAS-BLED scores are not sufficient to inform the need to withhold anticoagulation ; however , they are useful in making patients aware of their bleeding risk on anticoagulant therapy , and assisting in shared decision-making about starting , ceasing , or continuing an oral anticoagulant . There are few absolute contraindications to anticoagulation . These include severe bleeding diathesis ( for example , platelets less than 50 / μL ), active bleeding , severe anaemia under investigation or
11 , 12 recent high-risk bleeding events . Notably , a history of falls on its own is not a contraindication to the use of oral anticoagulants . 28
Anticoagulant choice
When choosing an anticoagulant , it
is important to make a distinction between valvular AF and non-valvular AF . Valvular AF is somewhat confusingly defined as AF occurring in a patient with a mechanical heart valve , or at least moderate mitral
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Figure 6 . Inpatient monitoring .
stenosis , or any degree of mitral stenosis ( see figure 8 ) in a patient with rheumatic heart disease . All other AF is defined as non-valvular AF , even in the presence of bioprosthetic heart
11 , 12 valves or other valvular disease . Those with valvular AF have a higher risk of ischaemic stroke than their non-valvular counterparts . 29 While there are limited data on the use of NOACs in valvular AF , the existing data point to the inferiority of NOACs when compared with warfarin in this cohort . RE-ALIGN ,
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a 2014 phase II randomised controlled trial ( RCT ) comparing warfarin with dabigatran in patients with mechanical heart valves , was ceased early because of excess strokes in the dabigatran arm . 30 The 2022 INVIC- TUS RCT , which compared warfarin to rivaroxaban in those with AF and rheumatic heart disease , showed greater all-cause mortality in the rivaroxaban arm . For these reasons , warfarin is the anticoagulant of choice for those with valvular AF . 31
In those with non-valvular heart
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disease , NOACs have been shown to be superior to warfarin in the absence of severe renal dysfunction that precludes NOAC use , providing a 19 % reduction in stroke and systemic embolism , and a 51 % reduction in haemorrhagic stroke when compared with warfarin in one RCT meta-analysis . 32 There are various considerations in NOAC dosing , with poor renal function the most common reason for dose reduction ( see table 3 ). Dabigatran is predominantly renally excreted in an unmetabolised form , |