Atrial Fibrillation

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

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

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

Aetiology

      Rheumatic heart disease Coronary heart disease (MI) Hypertension Myopericarditis Hypertrophic cardiomyopathy Cardiac surgery       Thyrotoxicosis Infection Alcohol abuse Pulmonary embolism Caffeine Exercise  Lone AF

Incidence / Prevalence

  1.7 / 1000 patients / year 3 / 1000 patients / year (>60 years)    0.4 - 1% (overall) 2 – 4% (>60 years) >8% (>80 years)

Classification

 New / Recent onset  < 48 hours  Paroxysmal   variable duration self terminating  Persistent   Non-self terminating Cardiovertable  Permanent   Non-self terminating Non-cardiovertable

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)

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

Normal Sinus Rhythm

‘Fast’ AF

‘Slow’ AF

Atrial Flutter

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

Diagnosis



Based on:

  

ECG Presentation Response to treatment

Treatment objectives



Rhythm / rate control



Stroke prevention

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

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

 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

Acute AF

Treatment will depend on:

    History of AF Time to presentation (<> 24 hours) Co-morbidities (CHD, CHF/LVSD etc) Likelihood of success (History)

 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)

Paroxymal AF

 Rhythm control*   Beta-blocker Class 1c agent or sotalol    If CHD - sotalol If LVD: Amiodarone Antithrombotic therapy as per risk assessment   Aspirin 75-300mg warfarin to INR 2-3  See later  Dronedarone?

*May be “Pill in the pocket”

Persistent AF

 Rhythm control  Beta blocker  No structural heart disease: Class 1c* or sotalol  Structural heart disease: amiodarone  Rate control  As for permanent AF   Antithrombotic therapy as per risk assessment Pre-cardioversion thromboprophylaxis of at least 3 weeks  If rate control, as for permanent AF * not if CHD present

Permanent AF

   Beta blocker or Calcium channel blocker and/or Digoxin  Antithrombotic therapy as per risk assessment  Aspirin 75-300mg  Warfarin to INR 2-3  See later  Amiodarone?

Stroke prevention

(non-rheumatic AF)

Stroke Risk Assessment (CHADS

2

)

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

Stroke Risk Assessment (CHA

2

DS

2

VASc)

 Alternative to CHADS 2         C H A D Chronic Heart Failure (1 point) Hypertension (1 point) Age > 75 years

(2 points)

Diabetes (1 point) S

V

Stroke, TIA or systemic embolisation (2 points)

vascular disease (1 point) A Age 65-74 years (1 point) Sc Sex category (1 point if female)

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

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

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