Atrial Fibrillation

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Atrial Fibrillation

• Steve McGlynn
• Specialist Principal Pharmacist (Cardiology),
• Greater Glasgow and Clyde
• Honorary Clinical Lecture,
• University of Strathclyde

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Some types of arrhythmia

• Supraventricular
• Sinus Nodal
• Sinus bradycardia
• Sinus tachycardia
• Sinus arrhythmia
• Atrial
• Atrial tachycardia
• Atrial flutter
• Atrial fibrillation
• AV Nodal
• AVNSVT
• Heart blocks
• Junctional
• Ventricular
• Escape rhythms
• Ventricular tachycardia
• Ventricular fibrillation

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Atrial fibrillation

• A heart rhythm disorder (arrhythmia). It usually
  involves a rapid heart rate, in which the upper
  heart chambers (atria) are stimulated to contract
  in a very disorganized and abnormal manner.
• A type of supraventricular tachyarrhythmia
• The most common arrhythmia

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Aetiology

• Rheumatic heart disease
• Coronary heart disease (MI)
• Hypertension
• Myopericarditis
• Hypertrophic cardiomyopathy
• Cardiac surgery

• Thyrotoxicosis
• Infection
• Alcohol abuse
• Pulmonary embolism
• Caffeine
• Exercise
• Lone AF

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Incidence / Prevalence

• 1.7 / 1000 patients / year
• 3 / 1000 patients / year (gt60 years)

• 0.4 - 1 (overall)
• 2 4 (gt60 years)
• gt8 (gt80 years)

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Classification

• New / Recent onset
• lt 48 hours
• Paroxysmal
• variable duration
• self terminating

• Persistent
• Non-self terminating
• Cardiovertable
• Permanent
• Non-self terminating
• Non-cardiovertable

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Symptoms / Signs

• Breathlessness / dyspnoea
• Palpitations
• Syncope / dizziness
• Chest discomfort
• Stroke / TIA
• 6 x risk of CVA
• 2 x risk of death
• 18 x risk of CVA if rheumatic heart disease

• Irregularly irregular pulse
• Atrial rate
• 300-600bpm
• Ventricular rate depends on degree of AV block
• 120-160bpm
• Peripheral rate slower (pulse deficit)

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Investigations

• Electrocardiogram (ECG)
• All patients
• May need ambulatory monitoring
• Transthoracic echocardiogram (TTE)
• Establish baseline
• Identify structural heart disease
• Risk stratification for anti-thrombotic therapy
• Transoesophogeal echocardiography (TOE)
• Further valve assessment
• If TTE inconclusive / difficult

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Normal Sinus Rhythm
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Fast AF
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Slow AF
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Atrial Flutter
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Investigations

• Electrocardiogram (ECG)
• All patients
• May need ambulatory monitoring
• Transthoracic echocardiogram (TTE)
• Baseline
• Structural heart disease
• Risk stratification for anti-thrombotic therapy
• Transoesophogeal echocardiography (TOE)
• Further valve assessment
• TTE inconclusive / difficult

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Diagnosis

• Based on
• ECG
• Presentation
• Response to treatment

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Treatment objectives

• Rhythm / rate control
• Stroke prevention

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Treatment strategies

• New / Recent onset
• Cardioversion
• Rhythm control
• Paroxysmal
• Rate control or cardioversion during paroxysm
• Rhythm control if needed

• Persistent
• Cardioversion
• Rhythm control
• Peri-cardioversion thromboprophylaxis
• Permanent
• Rate control
• Thromboprophylaxis

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Pharmacological Options

• Class Ic Anti-arrhythmics
• Flecainide / Propafenone
• Rhythm control
• May also be pro-arrhythmic
• Class II Anti-arrhythmics
• Beta-blockers
• Mainly rate control
• Control rate during exercise and at rest
• Generally first choice
• Choice depends on co-morbidities

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• Class III Anti-arryhthmics
• Amiodarone / Dronedarone
• Mainly rhythm control
• May be pro-arrhythmic
• Concerns over toxicity
• Class IV Anti-arryhthmics
• Calcium channel blockers (verapamil / diltiazem
  only)
• Rate control only
• Alternative to beta-blockers if no heart failure
• Digoxin
• Rate control only
• Does not control rate during exercise
• Third choice unless others contra-indicated

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Acute AF

• Treatment will depend on
• History of AF
• Time to presentation (ltgt 24 hours)
• Co-morbidities (CHD, CHF/LVSD etc)
• Likelihood of success (History)

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• Rate Vs. Rhythm control
• Rhythm control not feasible or safe
• Beta-blocker
• Verapamil
• Digoxin (CHF)
• Rhythm control if possible and safe
• DC cardioversion (if possible)
• Amiodarone (CHD or CHF/LVSD)
• Flecainide (Paroxysmal AF)

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Paroxymal AF

• Rhythm control
• Beta-blocker
• Class 1c agent or sotalol
• If CHD - sotalol
• If LVD Amiodarone
• Dronedarone?
• May be Pill in the pocket

• Antithrombotic therapy as per risk assessment
• Aspirin 75-300mg
• warfarin to INR 2-3
• See later

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Persistent AF

• Rhythm control
• Beta blocker
• No structural heart disease Class 1c or sotalol
  
• Structural heart disease amiodarone
• Rate control
• As for permanent AF
• not if CHD present

• Antithrombotic therapy as per risk assessment
• Pre-cardioversion thromboprophylaxis of at least
  3 weeks
• If rate control, as for permanent AF

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Permanent AF

• Beta blocker or
• Calcium channel blocker and/or
• Digoxin
• Amiodarone?

• Antithrombotic therapy as per risk assessment
• Aspirin 75-300mg
• Warfarin to INR 2-3
• See later

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Stroke prevention (non-rheumatic AF)
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Stroke Risk Assessment (CHADS2)

• C Chronic Heart Failure (1 point)
• H Hypertension (1 point)
• A Age gt 75 years (1 point)
• D Diabetes (1 point)
• S Stroke, TIA or systemic embolisation (2 points)
• Score lt 2 low risk, aspirin or anticoagulant
• Score 2 high risk, anticoagulant indicated

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Stroke Risk Assessment (CHA2DS2VASc)

• Alternative to CHADS2
• C Chronic Heart Failure (1 point)
• H Hypertension (1 point)
• A Age gt 75 years (2 points)
• D Diabetes (1 point)
• S Stroke, TIA or systemic embolisation (2 points)
• V vascular disease (1 point)
• A Age 65-74 years (1 point)
• Sc Sex category (1 point if female)

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Bleeding Risk Assessment(HAS-BLED)

• 1 point each for
• Hypertension
• Abnormal renal/liver function (1 for each)
• Stroke
• Bleeding history or predisposition
• Labile INR
• Elderly (age over 65)
• Drugs/alcohol concomitantly (1 for each)
• Drugs that increase bleeding, e.g. aspirin
• Alcohol excess

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Anticoagulants

• Warfarin remains standard anticoagulant at
  present
• 3 new oral anticoagulants (unlicensed for AF as
  of June 2011)
• Dabigatran (Direct thrombin inhibitor)
• Rivaroxiban (Factor Xa inhibitor)
• Apixaban (Factor Xa inhibitor)
• Fixed doses
• No monitoring
• At least as effective as warfarin
• Safer than warfarin?
• Much more expensive (even allowing for INR costs)
• Place in therapy not clear yet

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Conclusions

• AF is a common condition.
• Patients may be unaware of its presence and are
  therefore at risk of a stroke
• Alternative treatment strategies exist to control
  symptoms
• Alternative treatment strategies exist to reduce
  the risk of stroke
• Patient education and choice are central to
  improving the likelihood of treatment success