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Atrial Fibrillation
Atrial Fibrillation (AF)
Incidence
ƒ Overall prevalence :
–2.2 % in men
–1.7 % in women
ƒ Age prevalence :
–0.2 % at 25 to 34 years
–3.0 % at 55 to 64 years
ƒ By age 75, 10 % of population has AF
AF
Terminology
ƒ Chronic : present most or all the time
ƒ paroxysmal : short bursts interrupting
sinus rhythm
ƒ Lone : in younger people 20 to 30 years
with no apparent cause
ƒ Idopathic : in older people 50 years or
older with no apparent cause
Causes of AF
ƒ Valvular heart disease
–mitral stenosis
–mitral regurgitation
–aortic stenosis
–aortic regurgitation
Causes of AF (cont.)
ƒ Nonvalvular heart disease :
ƒPericarditis
ƒDilated and hypertrophic cardiomyopathy
ƒIschemic heart disease
ƒSystemic hypertension
ƒCongestive heart failure
ƒSick sinus syndrome
ƒCongenital heart disease
Causes of AF (cont.)
ƒ Pulmonary disease
ƒPulmonary emboli
ƒAcute or chronic airway disease
ƒPrimary pulmonary hypertension
Causes of AF (cont.)
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Toxic : alcohol (Acute & Chronic)
Metabolic : hypomagnesemia
Recent thoracotomy
Hyperthyroidism (occurs in 24 %)
Lone or idiopathic (8 / 100,000)
Mortality and Morbidity
ƒ doubles mortality risk in patients with
other heart disease
ƒ increases risk for stroke by 5 to 7 %
ƒ 45 % of cardiogenic emboli are
associated with AF
ƒ risk of pericardioversion emboli
increases considerably if AF has been
present for more than 2 days
Diagnosis
Symptoms
ƒ Are due to :
rapid ventricular rate
impaired left ventricular filling
elevated left atrial pressure and
decreased cardiac output
Diagnosis (cont.)
Symptoms
ƒ palpitations (commonest complaint)
ƒ neurological symptoms :
dizziness
lightheadedness
syncope or near syncope
ƒ shortness of breath
Diagnosis (cont.)
Symptoms
ƒ chest pain
ƒ reduction in exercise tolerance
ƒ aggravation of preexisting heart failure
or angina
ƒ a few patients may have no symptoms
Physical Findings
ƒ peripheral pulse : irregular
pulse deficit
ƒ fluctuating systolic blood pressure
ƒ absence of "a" wave in jugular venous
pulse
ƒ presence of "f" wave in jugular vein
ƒ varying intensity of first heart sound
(None of these indicators can be
diagnostic)
Diagnosis (cont.)
ECG
ƒ fibrillary waves
*called f wave
*best seen in V1, II, III, and AVF
*are fine to coarse
*rate 350 to 600 / minute
*they are pathognomonic for AF
*may not be clearly present & may
appear isoelectric
Diagnosis
ECG
ƒ presence of missing 'p' wave
ƒ irregularly irregular QRS complexes
ƒ presence of fibrillary waves
AF : Rate
ƒ usual rate is 100 to 160 / minute
ƒ if more than 160 / minute :
hyperthyroidism
adrenergic stimulations
ƒ fast and wide QRS
.preexcitation syndromes (WPW)
ƒ in AF and WPW, ventricular response may be as
rapid as 300 / min. or more and may degenerate to
VF
Rate (cont.)
ƒ sometimes it is difficult to differentiate
between AF & WPW from VT
ƒ if slow rate :
medications like digitalis
high vagal tone
sick sinus syndrome
Investigations
ƒ ECG
ƒ Echocardiogram :
condition of mitral & aortic valves
left atrial enlargement
left ventricular abnormalities
pericardial effusion
ƒ thyroid function studies
ƒ work up for coronary disease
ƒ work up for pulmonary emboli
Current therapy
ƒ Primary therapeutic goal
is control of ventricular
rate in new onset as well
as chronic Atrial
Fibrillation
Cardioversion
ƒ indications :
preexcitation syndrome
acute hemodynamic deterioration
ƒ Rx : synchronized cardioversion
joules : over 60 % can be converted
200 joules : over 80 % can be converted
failure :
procainamide IV (18 mg/kg) and then
cardioversion 360 joules
100
If
Paroxysmal AF
ƒ No Rx if :
episodes are rare
self limited and well tolerated has
no associated angina or heart
failure nor neurological symptoms
ƒ Rx if :
the patient has symptomatic episodes
AF : Rx
Sustained AF
ƒ AF less than 2 days
ƒ AF more than 2 days but TEE shows no
left atrial emboli
Rx :
control ventricular response
immediate cardioversion
AF : Rx
ƒ every patient deserves a chance at
cardioversion
ƒ the probability of successful long-term
cardioversion may be low if :
–AF has lasted for more than one year
–left atrium is greater than 4.5 cm by echo
AF : Rx
ƒ acute AF more than 2 days
ƒ long standing AF
Rx :
.control ventricular response
.anticoagulate
.have patient return back in 3 to 4
weeks for cardioversion
AF : Rx
ƒ rapid ventricular rate should be treated
initially with IV medication to avoid
emboli, and then oral medication
ƒ anticoagulation :
–warfarin for 4 weeks
–maintain INR 2 to 3 times control
–continue giving warfarin for 2 to 3 weeks
following cardioversion
AF : Rx
ƒ control ventricular response only
without restoring sinus rhythm if :
–long standing well-tolerated
sustained AF
–patient refractory to cardioversion
–patient who declines cardioversion
–recurrent AF
AF : Rx
ƒ in the absence of
contraindications, anticogualation
is recommended even without
cardioversion
AF : Rx
ƒ DO NOT USE
–digoxin
–beta blockers
–calcium channel blockers
in patients with preexitation
syndromes
AF : Rx
ƒ irregular slow ventricular
response to AF may
signal the presence of
AV node disease
AF : Rx
ƒ regular slow ventricular
response to AF may
signal the presence of
complete heart block
often caused by digitalis
toxicity
AF : Rx
Digoxin
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used for over 200 years
commonest drug for control of AF
IV onset of action is 30 minutes
maximal response occur in 1 to 4 hours
loading dose 0.1 to 0.6 mg
additional doses as needed 0.1 to 0.25 mg
every 4 to 6 hours
ƒ total dose in 24 hours is 1 mg
AF : Rx
Digoxin
ƒ for patients already on digoxin additional
dose is 0.25 mg every 6 to 12 hours
ƒ Beta blockers or calcium channel blocker
can be added if necessary
ƒ contraindications to digoxin :
*hypertrophic cardiomyopathy
*WPW syndrome
AF : Rx
Beta Blockers
ƒ ordinarily used
–Esmolol
–Propranolol
ƒ particularily used in
–thyrotoxicosis
ƒ adverse effects
–hypotension
–cardiac depression & bradyarrhythmias
–bronchospasm
AF : Rx
Beta blockers (cont.)
ƒ Esmolol
–rapid acting : half-life a few minutes
–loading dose 500 mcg / kg over 1 min.
– maintenance infusion 50 mcg / kg / min.
–loading dose can be repeated after 5 min.
–maintenance dose can be increased to 100
mcg /kg / min. as needed
–effects dissipate within minutes of
discontinuation of infusion
AF : Rx
Beta blockers (cont.)
ƒ Propranolol
–can be taken orally as well as IV
–dose : 1 to 3 mg boluses every 2 min.
until control achieved
–usual total dosage is 10 to 20 mg
–effective for 4 to 10 hours
–*Adverse effects :
ƒ hypotension
ƒ cardiac depresion
AF : Rx
Calcium channel blockers
ƒ verapamil
ƒ diltiazem
–Particularly useful in patients with
pulmonary disease who cannot take beta
blockers
–Adverse effects :
*hypotension
*bradyarrhythmias
*cardiac depression
AF : Rx
Calcium channel blockers (cont.)
ƒ Verapamil
–dose 5 to 10 mg given over 2 min.
–if no response : additional dose after 5 to 10 min.
–is usually effective for 4 to 6 hours
ƒ Diltiazem
–20 mg (0.25 mg / kg) bolus over 2 min.
–second bolus of 25 mg can be given 15 min. later (
if necessary)
–infusion of 5 to 15 mg / hour will control the
response for 24 hours
AF : Rx
Anticoagulation
ƒ long term Warfarin is
recommended for :
–mitral valve disease
–previous embolic events
–congestive heart failure
ƒ Aspirin 325 mg daily may be
considerd in patients with
nonvalvular AF
AF : Rx
Anticoagulation (cont.)
ƒ contraindications :
–active peptic ulcer
–alcoholism
–gait disorders
–uncontrolled hypertension
–previous major bleeding
–previous intracranial bleeding
AF : Summary
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incidence
terminology
causes
mortality and morbidity
symptoms
signs
ECG findings
investigations
current therapy