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.