Transcript Atrial Fibrillation

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
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
Arch Int Med 1998 158:1316
AF:stroke risk
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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
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
Arch Int Med 1994 154:1449
Apirin and clopidogrel
……are they safer than warfarin in AF
patients?
Vascular events and major bleeding:
ACTIVE-W final results
End point
Clopidogrel+ Warfarin Relative p
ASA
risk
Vascular events 5.64
(%/year)
3.63
1.45
0.0002
Major bleeding 2.4
(%/year)
2.2
1.06
0.67
Connolly S. American Heart Association Scientific
Sessions 2005; Nov 13-16, 2005; Dallas, TX.
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
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
Falk et al Ann Int Med 1987 106:503
Cardioversion
embolism risk 0-7%
– previous embolism
– prosthetic valve
– mitral stenosis
AF: low risk for cardioversion
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less than 2/7 duration
absence of thrombus on TOE
<60 years
no clinical risk factors
Cardioversion: high risk
• require 3/52 anticoagulation precardioversion
• 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
Digoxin and heart-rate
Botker et al Br Heart J 1991; 65:33741
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
Matsuda et al Cardiovasc Res 1991
25:453
In chronic atrial fibrillation
…..pulmonary-vein ablation
restores sinus rhythm
Circumferential Pulmonary-Vein Ablation
Oral, H. et al. N Engl J Med 2006;354:934-941
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 NEJM 2006;354:934-41
Percentages of Patients without Atrial Fibrillation and Atrial Flutter in the Absence of
Antiarrhythmic-Drug Therapy
Oral, H. et al. N Engl J Med 2006;354:934-941
Rate or rhythm
….do we really need to restore and
maintain sinus rhythm, or can we
simply maintain heart rate control?
AFFIRM
AFFIRM
Atrial
Fibrillation
Follow-up
Investigation of
Rhythm
Management
EP Show – December 2002
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
AFFIRM
Mortality results
Cumulative mortality
(%)
Rhythm control
Rate control
25
20
15
10
5
0
Year 1
EP Show – December 2002
Year 2
Year 3
Year 4
Year 5
N Engl J Med 2002;347:1825-33.
AFFIRM
Prevalence of warfarin
Greater prevalence of warfarin use in ratecontrol arm
•Rate-control arm: >85% throughout
the trial
•Rhythm-control arm: >70% throughout
the trial
EP Show – December 2002
N Engl J Med 2002;347:1825-33.
AFFIRM
Strokes
Event
Ischemic stroke
Rate
Rhythm
control
control
(n=2027) (n=2033)
77
(5.5%)
80
(7.1%)
After discontinuing
warfarin
25
44
During warfarin but
INR <2.0
27
17
EP Show – December 2002
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
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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
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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
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common
significant risk of stroke
potential for risk reduction
restoration of atrial systole desirable
maintenance of sinus rhythm a challenge