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ATRIAL FIBRILLATION
Dr ABHAY BAJPAIConsultant Cardiologist & Electrophysiologist
Epsom & St Helier University Hospitals NHS Trust St George’s Hospital NHS Foundation Trust
Electrical system
What characterises AF?
• AF is a rhythm disorder (arrhythmia) of the top chambers
• Rapid, disorganized electrical signals in the atria
• Conduction to the ventricles is limited by the AV node. AF leads to:– Irregular ventricular rate (pulse)
ECG tracing
Normal - Sinus rhythm
Atrial Fibrillation
AF Burden in England
• 2.4% = 1.36 million people in England have AF
• Only 1.6% diagnosed – 474,000 undiagnosed!
AF Burden in England
• Prevalence increases with age
• 2.9% in people aged < 45 • 16.6% in people aged 45-
65 • 80.5% in people aged >
65.
• Greater in men vs women, 2.8% vs 2.0%.
0
5
10
15
20Women (n=4,053) Men (n=2,590)
Pre
vale
nce
(%
)
The Rotterdam study
Age (years)55–59
65–6960–64
70–7475–79
80–84 85
AF Burden in England
Lifetime risk of developing AF
• At ≥40 years of age, the remaining lifetime risk for developing AF is:– 26.0% for men – 23.0% for women
• In the absence of previous chronic heart failure or heart attacks, the lifetime risk of AF at age ≥40 years is reduced similarly for both men and women:– 16.3% for men– 15.6% for women
Why do we develop AF?• Cardiovascular conditions
– High Blood pressure– Heart attacks / Angina (ischaemic heart disease)– Heart failure– Heart Valve disease
• Metabolic conditions– Obesity
– Diabetes mellitus
– Overactive Thyroid - Hyperthyroidism• Other
– Obstructive sleep apnoea syndrome – common in obese people – Pneumonia / chest infections / other lung conditions – Heart - Lung surgery – High alcohol intake– Familial
Lone AF
AF Epidemic has begun!
Year
2.08 2.442.26
5.1
5.1
0
2
4
6
8
10
12
14
16
1990 1995 2000 2005 2010 2015 2020 2025 2030 2035 2040 2045 2050
Patie
nts
with
AF
(mill
ions
)
5.42
11.7
15.2
4.34
9.4
11.7
3.33
7.5
8.9
2.94
6.8
7.7
8.4
10.2
3.804.78
10.3
13.1
5.16
11.1
14.3
5.61
12.1
15.9
5.6
5.9
2.66
6.1
6.7
Olmsted County data, 2006(assuming a continued increase in AF incidence)
ATRIA study data, 2000
Olmsted County data, 20061
(assuming no further increase in AF incidence)
Why treat AF ?• Independent risk factor for stroke
– Approximately 5 x increased risk1
– 1 in 6 strokes occur in patients with AF2
– AF-related strokes are typically more severe than strokes due to other aetiologies3,4
• Independent risk factor for mortality– Approximately twofold increased risk5
• Independent risk factor for heart failure – Heart failure further aggravates AF, worsening
overall prognosis6
1. Wolf PA et al. Stroke 1991;22:983–988; 2. Fuster V et al. Circulation 2006;114:700–752; 3. Lin HJ et al. Stroke 1996;27:1760–1764; 4. Jørgensen HS et al. Stroke 1996;27:1765–1769;5. . Benjamin EJ et al. Circulation 1998;98:946–952; 6. Wang T et al. Circulation 2003;107:2920–2925
AF significantly impairs quality of life
0
10
20
30
40
50
60
70
80
90
100
General health Physical health Social function Mental health
AF patients (n=152) Post MI patients (n=69) Healthy subjects (n=47)
**
*
*
1. Dorian P et al. J Am Coll Cardiol 2000;36:1303–1309; 2. Van den Berg MP et al. Neth J Med 2005;63:170–174
SF
-36
mea
n s
core
Patients with AF experience significant impairments to their QoL1–3
* p<0.001 compared to AF patients
Symptoms of AF
• Typical symptoms of AF include:– Palpitations (a sensation of rapid irregular heartbeat)– Fatigue– Shortness of breath– Dizziness/light headedness ...... Or Stroke– Chest pain - uncommon– Blackout - uncommon
• AF may not cause any symptoms– Approximately 1/3rd of patients
1. Fuster V et al. Circulation 2006;114:700–752; 2. Moran PS et al. The Cochrane Collaboration, April 2013
Classification of AF
Paroxysmal < 7 days , commonly < 48hrs
Persistent > 7days and < 1 year
Long standing persistent > 1year
Permanent
Progression of AF
1. Camm AJ et al. Eur Heart J 2010;31:2369–2429
Progression of AF is thought to be driven by structural changes in the atria,including electrical, contractile changes, known as atrial remodelling1
Different types of AF. The arrhythmia tends to progress from paroxysmal (self-terminating, usually <48 hours) to persistent (non-self-terminating or requiring cardioversion), long-standing persistent (lasting longer than 1 year) and eventually to permanent (accepted) AF. First-onset AF may be the first of recurrent attacks or already be deemed permanent1
Persistent(>7 days or requires
cardioversion)
Long-standingpersistent (>1 year)
Permanent(accepted)
Paroxysmal(usually ≤48 hours)
First diagnosed episode of AF
Diagnosis and monitoring of AF via ECG• An irregular pulse raises the clinical suspicion of AF• AF typically progresses from short, rare episodes to longer and more frequent
attacks
1. Camm AJ et al. Eur Heart J 2010;31:2369–2429
AF
Antiarrhythmic drugs
Anticoagulation
Rate control
Cardioversion
ParoxysmalSilent Persistent Long-standingpersistent
Permanent
‘Upstream’ therapy of concomitant conditions
Firs
t doc
umen
ted
Ablation
Cardiovascular conditions and risk factors are important predictors of AF
0 1 4 6 83 5 7 921 2 3 4 5 6 70
Diabetes mellitus 1.4 1.6
Hypertension 1.5 1.4
4.5 5.9
Valvular heart disease 1.8 3.4
Men (n=2,090)
MI 1.4 1.2; not significant
Women (n=2,641)
Odds ratio
The Framingham Heart Study
Heart failure
1. Benjamin EJ et al. JAMA 1994;271:840–844
Odds ratio
AF and stroke
• Stroke is the most serious ongoing risk associated with AF1
• In patients with AF, blood clots tend to form in the atria, particularly within the left atrial appendage, due to abnormal blood flow and pooling2
• These clots may travel to the brain, causing an ischaemic stroke2
• Around 20% of ischaemic strokes are caused by blood clots originating in the heart (cardioembolic); of these, AF is the most common cause3
1. Wolf PA et al. Stroke 1991;22:983–988; 2. Fuster V et al. Circulation 2006;114:700–752; 3. Paciaroni M et al. Stroke 2007;38:423–430
Patients with AF have an approximately fivefold increased risk of ischaemic stroke1
2-ye
ar a
ge-a
djus
ted
inci
denc
e of
str
oke/
1,00
0
Individualswith AF*
Individualswithout AF
Risk ratio=4.8p<0.001
0
10
20
30
40
50
60
Framingham Heart Study (N=5,070)
1. Wolf PA et al. Stroke 1991;22:983–988
*Patients were untreated with antithrombotic therapy when this study was performed in line with clinical practice at the time
AF-related stroke is preventable• By preventing clot formation in
the heart (thromboprophylaxis)
– Blood thinning therapy reduces the risk of stroke and thromboembolism but also increases the risk of bleeding
1. Fuster V et al. Circulation 2006;114:700–752; 2. Singer DE et al. Chest 2008;133:546S–592S; 3. Camm J et al. Eur Heart J 2010;31:2369–2429
Stroke risk in AF: the CHADS2 score
Congestive heart failure 1 point
Hypertension 1 point
Age >75 1 point
Diabetes 1 point
Stroke or TIA 2 points
CHADS2 score correlates with stroke rate
CHADS2 score
Str
oke
rat
e p
er 1
00 p
atie
nt
year
s w
ith
ou
t an
tith
rom
bo
tic
ther
apy
Gage et al, JAMA 2001;285:2864–2870.
CHA2DS2-VASc score: definition
Risk factor Points
Congestive heart failure/LV dysfunction +1
Hypertension +1
Age ≥75 years +2
Diabetes mellitus +1
Stroke/TIA/TE +2
Vascular disease (MI, aortic plaque, PAD)* +1
Age 65–74 years +1
Sex category (female) +1
Cumulative score Range 0−9
Score: 0 = low risk; 1 = intermediate risk; ≥2 = high risk
Lip et al Chest 2010;137:263–272
Blood thinning drugs
The Rat Poison ! WARFARIN
Warfarin significantly more effective than clopidogrel + ASA combined
Number at risk
Clopidogrel + ASA 3,335 3,168 2,419 941
Warfarin 3,371 3,232 2,466 930
Cumulative risk of stroke
0.05
0.04
0.03
0.02
0.01
00 0.05 1.0 1.5
Years
Cu
mu
lati
ve h
azar
d r
ates
Clopidogrel + ASA
RR=1.72 (1.24–2.37), ARR 0.99 p=0.001
Warfarin
An
nu
al in
cid
ence
(%
)
RR 1.44
ARR 1.67
p=0.0003
RR 1.10
ARR 0.21
p=0.53
10
8
6
4
2
0
5.60
3.93
2.42 2.21
Primary endpoint* Major bleeding
Clopidogrel/ASA
Warfarin
*Composite of stroke, non-CNS embolism, myocardial infarction and vascular death
1. ACTIVE Writing Group of the ACTIVE Investigators et al. Lancet 2006;367:1903–1912
ACTIVE-W results: patients with AF and ≥1 additional risk factor
Non-VKA Blood thinning drugs
Dabigatran
Rivaroxaban
Apixaban
Edoxaban
These drugs are not inferior to Warfarin and appear to have lesser risks of major bleeds
Less interaction with food or other drugs
No blood testing (no INR testing)
Rapid action, predictable action
Loss of action if not taken drug for 12-24 hrs
No antidote yet if bleeding
Anticoagulation carries a risk of bleeding
Thrombus prevention
Risk of bleeding
CHA2DS
2VASc score
versus
HAS-BLED Bleeding Risk Score
Unable to take blood thinners ?
-High bleeding risk
-Drug allergy/intolerance
Left Atrial Appendage Occluder Device
Consider pharmacological and/or electrical rhythm control for people with Atrial Fibrillation whose symptoms continue after heart rate has been
controlled or a rate-control strategy has not been successful
◊ Electrical Cardioversion (shock treatment)
◊ Rhythm maintaining drugs◊ - Beta-blocker ◊ - Sotalol, Flecainide, Amiodarone etc◊ Have potential side effects
◊ Rate controlling drugs◊ - Beta blockers, Digoxin, Diltiazem, etc
NICE AF Guideline June 2014
Rate and Rhythm Control
◊ Invasive
◊ Frequently require General anaesthesia
◊ 1% risk of complications overall
◊ 1:800-1000 risk of fatality from procedure
◊ Radiofrequency energy – ‘Burning’
◊ Cryothermal energy – ‘Freezing’
AF Ablation
◊ Works best for Paroxysmal AF patients
◊ (Pulmonary Vein Isolation)
◊ Poor results if AF > 1year or large Atrium
◊ (requires more extensive ablation)
◊ Multiple procedures common
NICE AF Guideline June 2014
AF Ablation
◊ No evidence currently of benefit in patients who are asymptomatic
◊ Blood thinners likely to continue longterm after ablation esp if high risk factors
◊ No evidence that improves prognosis / mortality from AF (except if AF related heart failure)
St Jude Medical
Radiofrequency Ablation – ‘Burning’
Radiofrequency Ablation – ‘Gaps’
Courtesy Google!
Medtronic Inc
Cryoballon Ablation – ‘Freezing’
Picture courtesy Gammie JS et al
Key pointsAF is the commonest rhythm problemThere is considerable related morbidity and mortality
Prevalence is increasing in epidemic proportions
Significantly increases risk of stroke, esp in patients with score >1Blood thinning agents significantly reduce stroke risk
Higher incidence in patients with common health problems & increasing age
Maintaining healthy lifestyle, controlling risk factors (eg Diabetes, BP)significantly reduces AF occurrence
Persistent AF greater than 1 year is challenging to treat
Rate control is equally good as rhythm control in asymptomatic patients
Ablation procedures offer high success rates in paroxysmal AF.