1. Atrial fibrillation

2. What is it?
AF is an arrhythmia is which electrical activity in the atria is disorganised
The AV node receives more electrical impulses than it can conduct, and many are blocked, resulting in an irregular ventricular rhythm
If untreated the ventricular rate averages bpm (or even lower)

3. AF is the most common arrhythmia in clinical practice
Prevalence doubles with each advancing decade from the age of 50 years
AF doubles mortality rate
Stroke risk is increased 6x and in AF with rheumatic heart disease 18x

4. What causes it? Most common
IHD, Hypertension, Mitral stenosis, Hyperthyroidism
Cardiac &/or valve conditions
Heart failure, rheumatic heart disease, pre-excitation syndromes (eg Wolff Parkinson White syndrome)
Non cardiac conditions
Lung cancer, acute infections
Dietary and lifestyle factors
Excess alcohol, excess caffeine, obesity

5. How might AF present in GP?
People with an irregular pulse +/-
Asymptomatic
Palpitations
Chest pains
Breathlessness
Syncope / giddiness
Reduced exercise tolerance, malaise or polyuria
A potential complication of AF such as stroke, TIA or heart failure

6. Diagnosis
Manual pulse palpation very sensitive but specificity less good
ECG
No P waves
Chaotic baseline
Irregular ventricular rate
Ventricular complexes look normal unless there is a conduction defect
If paroxysmal AF suspected AF and 12 lead ECG is normal then arrange ambulatory ECG
Bloods
CXR

7. Bloods? FBC – exclude anaemia
U+Es, bone profile, glucose – exclude electrolyte disturbances which may precipitate AF
LFTs and clotting – suitability for warfarin
CXR – lung cancer, detect heart failure

8. When to urgently refer
Pulse >150bpm &/or low BP (systolic < 90 mmHg)
Loss of consciousness, severe dizziness, ongoing chest pain or increasing breathlessness
Complication of AF
Stroke, TIA, acute HF

9. Key priority ― Detection and diagnosis NICE clinical guideline 36, June 2006
Case detection
Assessment
Rate- control
Rhythm- control
Referral
Follow-up OR
An ECG should be
performed in all patients,
whether symptomatic or
not, in whom AF is
suspected because an
irregular pulse has been
detected

10. Classification Paroxysmal
Intermittent and recurrent, but terminates spontaneously (35-65% of all cases)
Reverts to sinus rhythm within 7 days
Persistent
Does not convert spontaneously, but may be converted electrically or by the use of drugs
Lasts over 7 days and less than a year
Permanent
Long standing and resistant to cardioversion. Also term for long-standing AF (>1year) where cardioversion has not been attempted

11. Complications Stroke and thromboembolic events 6x greater risk
Heart failure
Tachycardia-induced cardiomyopathy
Critical cardiac ischaemia
Poorer life quality

12. Prognosis Mortality from AF up to 2x general population
Linked to severity of underlying heart disease (eg heart failure, cardiomyopathy or myocardial ischaemia)

13. Acute onset AF
Requires immediate hospitalisation and urgent intervention
Those at highest risk include:
Ventricular rate >150bpm
Ongoing chest pain
Critical ischaemia

14. Antithrombotic therapy
Treatment options
Antithrombotic therapy

15. Treatment options – antithrombotic therapy
Warfarin is more effective but balance this against a higher risk of a major bleed
Warfarin reduces relative risk of all strokes vs placebo by 60%
Aspirin reduces relative risk of all strokes vs placebo by 20%
Actual benefit is based on persons baseline risk

16. Key priority ― Assess for risk of stroke & thromboembolism NICE clinical guideline 36, June 2006
Case detection
Assessment
Rate- control
Rhythm- control
Referral
Follow-up OR
- Use the stroke risk
Stratification algorithm
to assess risk
- Use antithrombotic
therapy as appropriate
- Initiate antithrombotic
therapy without minimal
delay in patients newly
diagnosed with AF

17. Determine stroke/thromboembolic risk
Assess for risk of stroke and thromboembolism NICE clinical guideline 36, June 2006
Determine stroke/thromboembolic risk
High risk:
Previous ischaemic stroke/TIA or thromboembolic event
Age >75 with hypertension, diabetes or vascular disease
Clinical evidence of valve disease, heart failure, or impaired left ventricular function on echocardiography
Moderate risk:
Age >65 with no high risk factors
Age <75 with hypertension, diabetes or vascular disease
Low risk:
Age <65 with no moderate or high risk factors

18. Patients with AF NICE clinical guideline 36, June 2006
Determine stroke/thromboembolic risk
Low risk
High risk
Moderate risk
Consider anticoagulation
Consider anticoagulation
or aspirin
Aspirin 75 to 300 mg/day
if no contraindications
Contraindications to
warfarin?
YES NO
Reassess risk stratification
whenever individual risk
factors are reviewed
Warfarin, target INR = 2.5
(range 2.0 to 3.0)

19. CHADS2 Congestive heart failure = 1
Hypertension (or treated hypertension) = 1
Age older than 75 years = 1
Diabetes mellitus = 1
Previous Stroke or TIA = 2
Treat with aspirin if total score is 0 or 1
Use warfarin if score is 2 or more

20. Possible questions? How do the harms and benefits of aspirin compare?
How does low dose warfarin compare with adjusted dosing?
What about using clopidogrel instead of aspirin?

21. How do the harms and benefits of aspirin compare?

22. Harms from aspirin Take 1000 patients
6 will have a major extracranial bleeding in 1 year anyway
If they take aspirin 1 more will have a bleed caused by aspirin

23. Harms from warfarin Take 1000 patients
6 will have a major extracranial bleeding in 1 year anyway
If they take warfarin 3 more will have a bleed caused by warfarin

24. Anticoagulation
Assessment of bleeding risk should be part of clinical assessment prior to starting anticoagulation
Benefits and potential risks of anticoagulation should be discussed
Aim for INR between 2 and 3

25. Benefits of aspirin (low risk eg 1% per year)
Take 1000 patients
10 will have a stroke in 1 year (1%)
If aspirin is taken 8 will have a stroke
2 will be prevented from having a stroke

26. Benefits of warfarin (low risk eg 1% per year)
Take 1000 patients
10 will have a stroke in 1 year (1%)
If warfarin is taken 4 will have a stroke
6 will be prevented from having a stroke

27. Benefits of aspirin (moderate risk eg 3.5% per year)
Take 1000 patients
35 will have a stroke in 1 year (3.5%)
If aspirin is taken 28 will have a stroke
7 will be prevented from having a stroke

28. Benefits of warfarin (moderate risk eg 3.5% per year)
Take 1000 patients
35 will have a stroke in 1 year (3.5%)
If warfarin is taken 14 will have a stroke
21 will be prevented from having a stroke

29. Benefits of aspirin (higher risk eg 6% per year)
Take 1000 patients
60 will have a stroke in 1 year (6%)
If aspirin is taken 48 will have a stroke
12 will be prevented from having a stroke

30. Benefits of warfarin (higher risk eg 6% per year)
Take 1000 patients
60 will have a stroke in 1 year (6%)
If warfarin is taken 24 will have a stroke
36 will be prevented from having a stroke

31. How does low dose warfarin compare with adjusted dosing?

32. Adjusted dosing is better with no obvious increased harms

33. What about using clopidogrel instead of aspirin?

34. No evidence of significant benefit
Clopidogrel alone (within its unlicensed indications) is recommended for people who are intolerant of low dose aspirin and either have:
Experienced an occlusive vascular event
Have symptomatic PAD
Aspirin intolerance is either:
Proven hypersensitivity to aspirin containing medicines
History of severe dyspepsia induced by low dose aspirin

35. Treatment options
Rate or rhythm control

36. Treatment for persistent AF
2 treatment options
Rate control involves the use of chronotropic drugs or electrophysiological / surgical interventions
Rhythm control involves the use of electrical or pharmacological cardioversion for persistent AF, or suppression of recurrent (eg paroxysmal) AF
There is a need for appropriate antithrombotic therapy if rhythm control is chosen

37. NICE clinical guideline 36, June 2006. Quick Reference Guide

38. Treatment for paroxysmal AF
Patients can be highly symptomatic
3 main aims of Rx are to :
Suppress paroxysms of AF and maintain sinus rhythm
Control heart rate during paroxysms of AF
Prevent complications
Treatment strategies include out of hospital initiation of antiarrhythmic drugs : ‘pill in the pocket’ approach
Patients with paroxysmal AF carry the same risks of stroke and thromboembolism as those with persistent AF

39. Key priority ― choosing the most effective treatment NICE clinical guideline 36, June 2006
Some patients with
persistent AF will satisfy
criteria for either an initial
rate or rhythm control strategy
Indications for each Rx are
not mutually exclusive
Involve the patient in the
treatment decision
Take comorbidities into
account
Antithrombotic therapy
should always be used
Case detection
Assessment
Rate- control
Rhythm- control
Referral
Follow-up OR

40. Rate control What is it? Control the ventricular rate (AF remains)
How is it done?
Drugs that block AV node conduction (B blockers, Ca channel blockers, digoxin)
Why is it done?
Reduce symptoms and myopathy
Prevention of embolism & cardiomyopathy
Advantages?
As effective as rhythm control
Lower risk of adverse events
Lower cost
Less hospitalisation
Avoids antiarrhythmics
Disadvantages?
May not remove symptoms
Requires anticoagulation
Risk of tachycardiomyopathy
Atrial remodelling (permanent)
When may it be appropriate?
First line particularly in elderly with minimal symptoms
Patients at high risk of stroke

41. Rate control strategy
Try rate control 1st for patients with persistent AF :
Over 65
With CHD
With contraindications to antiarrhythmic drugs
Unsuitable for cardioversion
Without CCF

42. Rhythm control What is it? Restore and maintain sinus rhythm
How is it done?
Electrical / drug conversion (plus maintenance antiarrhythmic drugs)
Why is it done?
Reduce symptoms and myopathy
Prevention of embolism & cardiomyopathy
Advantages?
Better exercise tolerance
Improved haemodynamic function
Reverse modelling?
Less need for, but still requires, antithrombotic treatment
Disadvantages?
Difficult to maintain in long term
High adverse event rate
More hospitalisation
High rates of recurrence
When may it be appropriate
Young patients
New onset AF
Where rate control ineffective or symptoms remain

43. Rhythm control strategy
Try rhythm control 1st for patients with persistent AF :
Who are symptomatic
Who are younger
Presenting for the 1st time with lone AF
Secondary to a treated / corrected precipitant
With CCF

44. What about restoring sinus rhythm?
DC cardioversion restores sinus rhythm in >80%
In AF of recent onset drugs have a success rate of 40-90%
Sinus rhythm at 1y is maintained in 30% without antiarrhythmic therapy but in 50% with such therapy

45. Follow up and referral
Follow up after cardioversion should be at 1 month and then tailored to the individual
Reassess the need for anticoagulation at each review
Referral for further specialist intervention should be considered in those :
In whom pharmacological therapy has failed
With lone AF
With ECG evidence of any underlying electrophysiological disorder