Atrial fibrillation

• wavelets propagating in different directions

• disorganised atrial depolarisation without effective atrial contraction

• f waves 350-600 beats /min.

• ventricular response is grossly irregular at 100-160 beats /min. (in WPW >300/min or VF)

AF

• potentially serious consequences:

– embolism

– impaired cardiac output

– increased mortality

• extremely common

Arch Int Med 1998 158:1316

AF

• Annual rate of stroke at FU (mean 1.6 years) was 4.7%

• LA dimension not predictive but moderate to severe LV dysfunction (any visible dysfunction greater than mild global or focal hypokinesia) independently increased risk by odds ratio of 2.5

AF:stroke risk

• previous CVA/TIA (RR 22.5)

• diabetes (RR 1.7)

• hypertension (RR1.6)

• increasing age (RR 1.4/decade)

• CCF/IHD (RR 3.0)– one of these and annual stroke risk >4%

untreated

Atrial Fibrillation

• Analysis of 6 randomised primary prevention trials has shown a 68% reduction in annual rate of stroke (4.5%-1.4%)

• reduction in mortality of 30% in the treated group

• annual rate of bleeding was 1.3%; major haemorrhage 0.3% and associated with age, hypertension and increased intensity of anticoagulation

Arch Int Med 1994 154:1449

Meta-analysis of anticoagulant studies

• aspirin (325 mg) associated with 44% stroke rate reduction

• Warfarin about 50% more effective than aspirin for prevention of ischaemic stroke

Apirin and clopidogrel

……are they safer than warfarin in AF patients?

Connolly S. American Heart Association Scientific Sessions 2005; Nov 13-16, 2005; Dallas, TX.

Vascular events and major bleeding: ACTIVE-W final results End point Clopidogrel+

ASAWarfarin Relative

riskp

Vascular events (%/year)

5.64 3.63 1.45 0.0002

Major bleeding (%/year)

2.4 2.2 1.06 0.67

AF/intensity of anticoagulation

AF

considerable heterogeneity of patients with AF so treatment strategies will differ:

– restoration and maintenance of SR

or– control of ventricular rate and anticoagulation

Falk et al Ann Int Med 1987 106:503

AF: digoxin is not the answer

• Cardioversion may be achieved with either

• electrical shock or with antiarrhythmic drugs

• digoxin is not effective in cardioverting patients from AF to SR

Cardioversion

embolism risk 0-7%– previous embolism– prosthetic valve– mitral stenosis

AF: low risk for cardioversion

• less than 2/7 duration

• absence of thrombus on TOE

• <60 years

• no clinical risk factors

Cardioversion: high risk

• require 3/52 anticoagulation pre-cardioversion

• 4/52 after cardioversion

Management of AF

• cardioversion results in SR in 90% of cases

• SR is only maintained in 30-50% at one year

• class 1a, 1c and III agents increase likelihood of maintained SR from 30-50% to 50-70% at one year

Botker et al Br Heart J 1991; 65:337-41

Digoxin and heart-rate

Matsuda et al Cardiovasc Res 1991 25:453

AF: digoxin is not the answer

• Both beta and calcium channel blocking agents control ventricular rate in AF patients at rest and on exercise

• but the negative inotropic and chronotropic effects may be deleterious to exercise tolerance

In chronic atrial fibrillation

…..pulmonary-vein ablation restores sinus rhythm

Oral, H. et al. N Engl J Med 2006;354:934-941

Circumferential Pulmonary-Vein Ablation

Oral H et al NEJM 2006;354:934-41

Ablation and chronic AF

• 146 patients with refractory chronic AF were randomly assigned to pulmonary-vein ablation or to receive short-term therapy with amiodarone.

Oral, H. et al. N Engl J Med 2006;354:934-941

Percentages of Patients without Atrial Fibrillation and Atrial Flutter in the Absence of Antiarrhythmic-Drug Therapy

Rate or rhythm

….do we really need to restore and maintain sinus rhythm, or can we simply maintain heart rate control?

EP Show – December 2002

AFFIRM

AFFIRM

AtrialFibrillation Follow-up Investigation of Rhythm Management

Inclusion criteria

Wanted to focus on the elderly

• >65 years of age

• Patients where the atrial fibrillation itself was a risk for morbidity or mortality

• Able to tolerate at least 2 drug regimens in both treatment arms

Treatment strategies

Patients were randomized to a strategy, not a specific drug regimen

• Pharmacological therapies: allowed any drug approved by North American regulatory authorities. Drugs could be added if they were approved during the trial

• Nonpharmacological therapies: allowed designated therapies once a patient failed 2 drug therapies

EP Show – December 2002

AFFIRM

Mortality results

0

5

10

15

20

25

Cum

ula

tive m

ort

ality

(%

)

Year 1 Year 2 Year 3 Year 4 Year 5

Rhythm control Rate control

N Engl J Med 2002;347:1825-33.

EP Show – December 2002

AFFIRM

Prevalence of warfarin

Greater prevalence of warfarin use in rate-control arm

•Rate-control arm: >85% throughout the trial

•Rhythm-control arm: >70% throughout the trial

N Engl J Med 2002;347:1825-33.

EP Show – December 2002

AFFIRM

Strokes

1727During warfarin but INR <2.0

Event

4425After discontinuing warfarin

80 (7.1%)77 (5.5%)Ischemic stroke

Rhythm control

(n=2033)

Rate control

(n=2027)

N Engl J Med 2002;347:1825-33.

AF

….other issues.

Lone AF

• Under age 60

• without structural cardiac disease, hypertension, diabetes, coronary heart disease or thyrotoxicosis

• low annual risk

• manage off warfarin

AF: digoxin is not the answer

In WPW and AF digoxin enhances conduction through the accessory pathway. It may lead to VF and death and should not be used in known or suspected WPW

Paroxysmal AF

• Accounts for about 65% of all AF

• commoner in young and in men

• similar stroke rates to chronic AF

• management should probably be similar too

Atrial Fibrillation-the elderly

• Median age of patients with AF is 75

• the risk of both AF and haemorrhage increase with age

• risk of bleeding shown to be a function of intensity of anticoagulation

Atrial Fibrillation-the elderly

• Close control of INR is essential and should be maintained below 3

• the elderly with clinical profiles indicating an increased risk of bleeding should not receive warfarin and aspirin is a reasonable compromise

Over 75 years

even without additional risk factors likely to benefit from

anticoagulation; care with anticoagulant monitoring

Aspirin

• 60-75 years • no clinical risk factors• risk =2%/year• warfarin contraindicated• unreliable patient

Warfarin for…...

• AF

• risk factors for stroke

• good candidate for anticoagulation

Atrial fibrillation: conclusions

• common

• significant risk of stroke

• potential for risk reduction

• restoration of atrial systole desirable

• maintenance of sinus rhythm a challenge