Download Atrial Fibrillation To Cardiovert or not to Cardiovert ?

Atrial Fibrillation
To Cardiovert or not to Cardiovert ?
Brian Clarke.
www.3bv.org
Bones Brains & Blood vessels
Atrial Fibrillation
To Cardiovert or not to Cardiovert ?
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AF Guidelines
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Definition & Classification
Incidence / Prevalence
Pathophysiological Mechanisms
Causes & Clinical Manifestations
Management
 Pharmacological (Rate, Rhythm, Stroke Prevention)
 Maintaining NSR
 DCCV
Atrial Fibrillation
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Common Arrhythmia characterised by
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Chaotic supraventricular activity
P-waves replaced with fibrillatory waves of varying amplitude, shape & timing
Deterioration of atrial mechanical function & loss of the atrial contribution to LV filling
Varying Ventricluar response rates
Classification
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Several clinical classification schemes, but none fully account for all aspects of AF
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Various labels:
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Acute, Chronic, Paroxysmal, Intermittent, constant, persistent, permanent
Atrial Fibrillation – categories not mutually exclusive
Epidemiology
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4.5 million in EU
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30% of Arrhythmia hospitalizations
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Hospital admissions due to AF have increased 66% over the past
20 years due to an aging population
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Estimated cost burden per patient €3000/yr
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Overall burden €13.5 billion (EU)
Atrial Fibrillation
(esc 2006)
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Prevalence
 0.4 – 1% of general population
 8% of those over 80
 Median age is 75 yrs
 Higher in men.
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Incidence
 0.1% per year in <40yrs
 2% per year males >80
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Pathological changes are characterised by fibrosis and loss of muscle
mass in the left atrium. Atrial stretch and dilatation occurs.
AF
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Causes/Associations
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Obesity
IHD
Valve disease
BP
Cardiomyopathy
Congen HD, ASD, VSD
Haemochromatosis
Amyloid
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Acute/Temporary
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Alcohol, Holiday Heart
Surgery
MI
Pericarditis
PE
Hyperthyroid
Pneumonia, sepsis
Symptoms: Palpitations, Fatigue, Light Headedness, SOB, Pre-syncope
Management
1.
Prevent Embolism
n
Rate control
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n
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60-80 bpm at rest
90-115 bpm during moderate exercise
Rhythm control
n
Cardioversion – Drugs or Electrical
n
Ablation techniques (Pulmonary Vein Isolation)
Thromboembolism
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Thrombotic material most often arises in the Left Atrial Appendage
the site of 95% of detected thrombus
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Begins with virchows triad of stasis, endothelial
dysfunction & hypercoagulability
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Decreased LAA flow is assoc with Spont ECHO
contrast
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However upto 25% of CVA in pts with AF may be due to intrinsic
cerebrovascular disease and other cardiac sources or
atheromatous pathology in the proximal aorta
Thromboembolism - Stroke
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1/6 strokes are AF related
 35% in the over 80’s
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5% stroke rate per year in non-valvular AF
 2-7 fold inc risk (compared to nsr stroke rate)
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7% per year rate of brain ischemia (including silent strokes/TIA)
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Upto a 17 fold stroke risk with Rheumatic heart disease
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AF related strokes are more disabling than non-AF strokes
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Estimated that only 67% of pts eligible for warfarin are prescribed it
Warfarin & Stroke risk Reduction
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Warfarin reduces AF related stroke risk by 61%
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Major bleeding: 0.9 - 2.2% (1.2% per yr over 5 RCT)
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ICH rate:
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Aspirin offers modest protection
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AHA/ESC/ACA
0.1 - 0.6%
Meta-analysis 1999: 19% reduction
Evidence based on 300mg dose, higher GI risk (x2 75mg dose risk) but
limited evidence at the lower doses
Combining with clopidogrel is still inferior to warfarin alone
12 Stroke Risk Classification Schemes (Non-Valvular AF)
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Atrial Fibrillation Investigators: 1994
SPAF: 1995
European AF Trial Study Group: 1995
4 core features
Independently predict
stroke
AFI: 1998
SPAF: 1999
CHADS2: 2001
1. BP
2. Advanced Age
3. Prior CVA/TIA
4. DM
American College Chest Physicians: 2001
Framigham Heart Study: 2003
Van Walraven et al: 2003
ACCP: 2004
BAFTA (Birmingham AF Treament of the Aged): 2006
ACC/AHA/ESC Guidelines: 2006
CHADS2 Scoring System JAMA 2001
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? To Warfarinise – CHADS2 - score total of 6
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CHF
1
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Hypertension (>160)
Age (>75)
Diabetes
1
1
1
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Stroke (TIA / CVA)
2
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Consider if CHADS2 >1
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Note CHADS2 does not take into account valve disease, which clearly, if present,
further increases the risk of Stroke
Stroke Risk
CHADS2
Annual Stroke Risk %
0
1.9
1
2.8
2
4.0
3
5.9
4
8.5
5
12.5
6
18.2
Is it Safe to Anticoagulate Older patients ?
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BAFTA 2007 in 234 GP practices in UK Midlands
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Trial of 973 pts aged > 75yrs (mean age 81)
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All with Af randomised to Aspirin 75mg or Warfarin
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Followed for average of 2.7 yrs
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Warfarin reduced risk of fatal or disabling stroke in this age group
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(9.9% vs 4.4%, RRR 50%)
Extra-cranial Haemorrhage risk:
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Aspirin gp (1.6%) Warfarin (1.4%)
Pharmacological Management
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AFFIRM NEJM 2002
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No difference in Stroke rates in those assigned to rate v rhythm control
More of the rhythym controlled gp were hospitalized or gad ADR’s
RACE NEJM 2002
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rate was not inferior to rhythm control in preventing of death/morbidity
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ACE-i/ARB have been shown to decrease incidence of AF LIFE, Losartan
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Decision to cardiovert someone should be based on:
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Severity of the associated symptoms
Inability to rate control
Patient preference
AHA/ESC Rate Control Recommendations
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Class 1 Recc:
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Persistent or permanent AF: bBlockers or CaChB to control rate
In AFFIRM bB (70%) were better than CaChB (54%) in achieving target Rates
Acutely: IV bB or CaChB with normal LV
Acutely: IV Dig or Amiodarone in those with HF
Adequacy of rate control should be measured during exercise
Digoxin is effective orally only in sedentary pts with HF or LV dysfunction
Class 2a Recc:
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Combination of Dig & bB can be used
Reasonable to consider ablation procedure if drugs fail or significant s/e
Rate Control: Drug Recommendations
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Class 2b Recc:
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Addition of amiodarone to other drugs to control rate is reasonable
where above fail to rate control
Class 3 Recc:
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Dig should not be used to control rate in parox AF
Catheter Ablation should not be attempted without trial of drugs
In decompensated HF CaChB should not be used
Cardioversion: Drug Recommendations
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Drugs are simpler but often less effective than electrical cardioversion.
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Drugs most effective if AF <7days duration
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Spontaneous Cardioversion occurs in proportion of pts with short duration AF
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Drugs much less effective if AF is persistent
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Proven CV Efficacy:
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Amiodarone
Flecainide:
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Useful PO/IV in pts with AF < 7days,
Without evidence of sinus/av node disease, BBB, QT prolongation Brugada or structural heart
disease.
Digoxin and sotalol should not be used to CV
Digoxin no better than placebo in cardioverting
Maintain NSR: Drug Recommendations
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Amiodarone:
 more effective than Sotalol (69%v 39% over 16 months)
 off set by long term s/e profile
 Median time to AF recurrence: amiod (487d) v sotalol (74 d)
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Sotalol:
 A non-selective β-blocking drug with class III activity
 Not effective in CV of AF.
 May be used to prevent AF recurrences
 QT interval <450ms.
 Little or no Heart disease & normal electrolytes
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Beta-blockers:
 Not primary therapy to maintain NSR
 Controls ventricular rate in recurrences of AF
Maintenance of NSR - Drugs
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Treat the precipitating cause
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Define goals of treatment: AF is a chronic life-long disorder that is likely to recur at
some point in most patients.
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Maintain NSR will in some patients: suppress s/s, improve exercise tolerance or
prevent tachy induced CM
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Because RF for recurrence of AF are RF for stroke (age, BP, LA enlargement, LV
dysfunction) correction to NSR may not reduce that patients inherent stroke risk
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Well tolerated recurrences of AF is reasonable as a successful outcome of AAR drug
therapy
Electrical Cardioversion
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Synchronised ECV
 100-150j biphasic, up to 200j
 Higher Initial energies significantly more effective
 Higher energies: in larger people and AF of long duration
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Success enhanced by preloading with Amiodarone or Sotalol (AHA, ESC)
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Risk
 Embolic event (1-7%) – cluster in the first 10 days post ECV
 Bradycardia, Heart Block, Temporary Sinus arrest
 VF, VT if not synchronised
 Arrhythmia risk increased by Hypo-kalemia, Dig toxicity
 Relatively low associated Anaesthetic risk
Conclusions
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Success rates for ECV in maintaining NSR: ultimately poor
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Longer Surveillance period post CV (more than the usual 6 weeks)
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? 6months to capture those reverting to AF
When selecting patients for ECV
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But procedure can still be offered once mindful of the likellihood of reverting to AF
Symptomatic AF – probably only real reason to CV
Think of cause & Estimate length of time in AF (<1yr)
CHADS2
ECHO parameters, LA size up to 4.5cm
Consider Amiodarone/sotalol pre-CV : especially if second attempt
Use ACE/ARB to reduce LA stretch
Consider ablation if repeated attempts fail and pt still symptomatic
Asymptomatic AF & CHADS2 >1: rate control and anti-coagulate
References
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Lane DA, Lip GY. Barriers to anticoagulation in patients with atrial fibrillation: changing physician-related factors.
Stroke. 2008 Jan;39(1):7-9.
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Fuster V, Ryden LE, Cannom DS, Crijns HJ, Curtis AB, Ellenbogen KA, et al. ACC/AHA/ESC 2006 Guidelines for
the Management of Patients with Atrial Fibrillation: a report of the American College of Cardiology/American Heart
Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice
Guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients With Atrial
Fibrillation): developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm
Society. Circulation. 2006 Aug 15;114(7):e257-354.
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Mant J, Hobbs FD, Fletcher K, Roalfe A, Fitzmaurice D, Lip GY, et al. Warfarin versus aspirin for stroke prevention
in an elderly community population with atrial fibrillation (the Birmingham Atrial Fibrillation Treatment of the Aged
Study, BAFTA): a randomised controlled trial. Lancet. 2007 Aug 11;370(9586):493-503.
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Wyse DG, Waldo AL, DiMarco JP, Domanski MJ, Rosenberg Y, Schron EB, et al. A comparison of rate control and
rhythm control in patients with atrial fibrillation. N Engl J Med. 2002 Dec 5;347(23):1825-33.
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Gage BF, Waterman AD, Shannon W, Boechler M, Rich MW, Radford MJ. Validation of clinical classification
schemes for predicting stroke: results from the National Registry of Atrial Fibrillation. JAMA. 2001 Jun 13;285(22):
2864-70.