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Atrial Fibrillation

A 60 year old male patient with a history of hypertension isreferred for assessment.He informs you that he has been well except for a slight stroke

4 years ago but made a full recovery from same.Apart from an irregular pulse there is no other relevant historyand he is not diabetic.Clinical examination suggests atrial fibrillation which is

confirmed on ECG. Examination was otherwise normal. Youare aware of the relationship between atrial fibrillation andstroke.What are the treatment options for this man ?

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Atrial Fibrillation

Ruth Barrett

Meena GrewalKaren Whelan

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Atrial Fibrillation

Atrial Fibrillation is a chaotic, irregular atrial rhythm at 300-600 bpmthe AV node responds intermittently, hence an irregularventricular rate.

It occurs in 5-10% of patients >65.It also occurs, particularly in a paroxysmal form, in youngerpatients.

Classification:Continuous

Acute ( 48 hrs) Chronic

Paroxysmal

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Causes

Cardiac causes:Ischaemic Heart Disease

Hypertensive Heart Disease (LVH)Valvular Heart Disease (esp Mitral Stenosis)Pericarditis

Cardiomyopathy, heart failure

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Metabolic:Thyrotoxicosis

Alcohol (acute or chronic)Pulmonary

Pulmonary EmbolismPneumoniaCOPDCor Pulmonale

OtherIdiopathic/ lone AF

K, MgPost-opInfection e.g UTI

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Symptoms

May be asymptomaticChest painPalpitations

DyspnoeaFaintness

Signs

Irregularly irregular pulseSigns of LVF

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Investigations

ECGAbsent P wavesIrregular QRScomplexes

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Investigations

Look for an underlying causeU&Es

Cardiac enzymesTFTsConsider ECHO to look for left atrial

enlargement, mitral valve disease, poor LVfunction and other structural abnormalities

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Chronic AF

1. Rate or Rhythm control

2. Warfarin or Aspirin/Clopidogrel or

no anticoagulation

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Rate Control

Rate control is the first option if

>65 yearsCoronary artery diseaseUnsuitable for cardioversion

Anticoagulants contraindicated

AF lasting longer than 1 year Mitral stenosis present Past attempts have failed An ongoing reversible cause (eg. Thyrotoxicosis)

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Rate control

1. Beta blockeror2. Rate limiting Ca channel blocker

-Verapamil / DiltiazemIf no effect - add3. Digoxin

Rate control is as effective as rhythm control in decreasingmorbidity and mortality in most people with chronic AF.

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Beta Blockerpropranolol, metoprolol

C/I2nd or 3 rd degree heart blockunstable heart failureasthmaPeripheral vascular disease ( intrinsic sympathomimetic BB preferred)

Cau tionDiabetes masking of hypoglycaemia (cardioselective BB preferred)COPD (c/i if exacerbation of COPD occurs)Renal Failure patients water soluble BB may accumulate (atenolol)

Other SEimpotencesedation, sleep alteration

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Rate limiting CCBVer ap amil most cardioselective CCB.

Potent negative chronotropic and inotropic effectsDilti azem cardio and vasculitic effects

C/IHypotension2nd /3 rd degree HBHeart Failure

SEVasodilator effects headache, flushing, dizziness.Constipation

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DigoxinC/I

WPW syndromeHOCM2nd degree Hb

SE Cardiac- bradycardia, HB, arrythmiasParasympathetic activity n&v, diarrhoea, blurry yellow vision.

toxicity with renal failure, hypokalemia, amiodarone, verapamil

NotesDose is individualised (+/- plasma monitoring)Low dose for elderly/renal impairment.Amiodarone and Verapamil increase digoxin levels

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Rhythm Control

Rhythm control is first choice if

Younger patientSymptomaticCCF

Px for first time with lone AFAF is secondary to a corrected precipitant

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Rhythm Control

DC Electrical CardioversionPre-cardioversion echoPre treat x4 weeks with sotolol or amiodaroneif risk failure (past failure or AF recurrence)

Pharmacological CardioversionF lec a inide if no structural heart diseaseIVamiod a rone if structural heart disease

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FlecainideClass 1C (Na+ channel blocker)

C/I

Heart Failure

Hx of MI

valvular disease

SE

dizziness

visual disturbances

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AmiodaroneClass 3 ( K+ channel blocker)

M onitorTFTS x6monthsLFTs x6monthsCXR and PFTs prior to initiation

SEHypo/hyperthyroidismphotosensitivity rashescorneal microdeposits dazzled by headlightsperipheral neuropathy and myopathy

Noteslong half-life. Use other antiarrythmics with caution in following 3months.Drug interactions warfarin, digoxin, phenytoin.Suspect pneumonitis if progresssive SOB occurs.

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Other options

AV node ablationPacemakerPulmonary vein ablation

Notes on anti-arrythmicsNegative inotropic effects tend to be additiveUsually initiate on an inpatient basisCheck QT interval on initiation

K+ enhances arrythmogenic effect of manydrugs.

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Thromboprophylaxis

Major complication of AF is thromboembolismresulting in:

Ischemic stroke (emboli to cerebral circulation) NOTE:AF is an independent risk factor for stroke

Systemic emboli to renal arteries, cornary arteries,superior mesenteric artery , splenic or femoral arteries

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Anticoagulation

Continous AF:Valvular AF : anticoagulate with warfarin (INR 2-3, formechanical valves INR 2.5-3.5)

Non-valvular AF: whether or not to anticoagulatedepends on the risk of ischemic stroke which isestimated with CHADS 2 score

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CHADS2 Score: Risk Assessment Tool

C = Congestive Heart Failure (EF 160mmHg) (1)A = Age > 75 years old (1)D = Diabetes (1)S = Prior cerebral ischemia (stroke or TIA) (2)

Note: the higher the score, the higher the riskof stroke

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How to interpret CHADS 2 score

CHADS2 2: treat with warfarin (INR 2-3)unless contraindicated or annual major bleeding risk exceeds3%

CHADS2= 1: treat with aspirin or warfarincan perform ECHO and if underlying structural abnormality,use warfarin

CHADS2 = 0: treat with aspirin81-325 mg daily or if warfarin is contraindicated

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Contraindications to Warfarin use

Bleeding diathesisPlatelets < 50 x 109/LBP>160/90 (consistently raised)

Renal impairment Creatine clearance< 10ml/min

Peptic ulcer diseasePregnancy

Bacterial endocarditisCaution: Hepatic or Renal disease, recent surgery,patient factors falls risks, compliance issues

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Note on ClopidogrelIf patients are aspirin intolerant, clopidogrel may be used

Clopidogrel is contraindicated in: Active pathological bleeding, especially GI or intracranial Severe liver impairment Pregnancy and breastfeeding

Side effects:risk of bleedingGI upset

Note: when compared to warfarin, aspirin and clopidogrel togetherare not superior in preventing ischemic stroke

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No Thromboprophylaxis

If stable sinus rhythm has been restoredNo risk factors for emboli

AF recurrence unlikely (i.e. no failedcardioversions, no structural heart disease, noprevious recurrences, and no sustained AF for>1 year)

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Acute AF

Acute AF (48 hours since onset and undergoing either electrical or

drug cardioversion, there is a risk of thromboembolismfrom the left atrium or left atrial appendage

therefore, anticoagulate with warfarin at least 3 weeks

prior and 4 -6 weeks after cardioversion. However, if 48hour time period has elapsed, cardioversion withoutanticoagulation is okay if trans-oesophageal echo shows nointracardiac thrombus.

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Acute AF

Chest 2009;135;849-859

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Paroxysmal AF(NICE 2006)

Pill in the PocketFlecainide PRN may be tried if:

-infrequent AF- BP >100 systolic- no past LV dysfunction

If this fails, try regular Beta BlockerAnticoagulate (Aspirin/Warfarin)

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Summary

AF

Continuous

Acute

Digoxin

B-Blocker

Verapamil

Amiodarone

DC shock

Chronic

Digoxin

B-Blocker

Amiodarone

anticoagulation

Paroxysmal

Flecainide

Sotalol

Amiodarone

+/- anticoagulation

1. Treat any reversible cause2. Control ventricular rate3. Consider cardioversion4. Prevent emboli

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References

Oxford handbook pages 116-117European Journal of Internal Medicine 20 (2009)672-681, Review article: Atrial Fibrillation:

Mechanistic insights and treatment optionsBlood Reviews 23 (2009) 241-244: AtrialFibrillation and Coagulation: who and when?Chest 2009;135;849-859: Acute Management of Atrial FibrillationSt James Prescriber s guide 2009