Atrial Fibrillation

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Atrial Fibrillation

• Overview and Management

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What is it?

• Most commonly seen narrow complex arrythmia.
• Most common irregularly irregular rhythm
• Affects more than 10 of age gt80.
• Men gt Women
• Multiple impulses from different areas move
  toward the AV node.
• Produce an irregular ventricular response
• Rate depends on of impulses conducted.

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Why is it important?

• Can cause significant symptoms usually secondary
  to RVR
• Range from severe (pulm edema, palpitations,
  angina, syncope) to none at all
• Prolonged tachycardia may lead to cardiomyopathy
• May lead to clot formation and eventually a
  embolic stroke.
• Irregular contractions lead to stasis

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Classification

• Paroxysmal end lt7 days
• Persistent last gt 7 days
• May terminate on its own or by cardioversion
• Permanent - gt 1 year and cardioversion has not
  been attempted or failed
• Lone AF any of the above without structural
  heart disease
• Only applies to AF unrelated to a reversible cause

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Causes/Associations

• Cardiac Surgery
• Pericarditis
• MI
• Hyperthyroidism
• PE
• Pulmonary disease
• Stress, Fever, Excessive EtOH intake, Dehydr.
• Treat associated cause and the abnormal rhythm

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Diagnosis

• History and PE onset, pattern, frequency,
  symptoms, precipitating factors, other diseases
• Symptoms related to severity of underlying heart
  disease
• EKG no p waves, irregularly irregular rhythm,
  tachycardia

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What do we do about it?Four Issues

• Rhythm control
• Rate control
• Choosing between the two
• Prevention of emboli
• ? Choice depends on the type, patient preference

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AAFP/ACP Recommendations on 1st diagnosed episode
of AF

• Rate control with chronic anticoagulation is for
  the majority
• Beta blockers and calcium channel blockers for
  rate control
• Anticoagulation warfarin
• For rhythm control both DC and pharmacologic
  cardioversion appropriate
• After cardioversion typically no antiarrythmics
  

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Rhythm Control

• Synchronized DC cardioversion and pharmacologic
  cardioversion
• gt 48 hours, or lt48 hrs with mitral stenosis or hx
  of emboli you must anticoagulate
• 3-4 weeks of INR at 2-3
• Unless TEE has excluded thrombi
• If unstable DC cardioversion
• If stable and correction of underlying problem
  does not help either choice

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Compare Shock vs. Drugs

• DC cardioversion 75-93 successful
• Depends on atrial size and duration of AF
• Drugs 30-60 successful
• lt7 days dofetilide, flecainide, ibutilide,
  propafenone
• gt7 days dofetilide

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Maintenance of NSR

• Only 20-30 percent of patients stay in sinus for
  gt1 year.
• Consider Antiarrythmics
• Dont in patients with AF less than 1 year, no
  atrial enlargement, reversible cause
• Consider it in patients with high risk of
  recurrence
• Risks generally outweigh benefits.
• Amiodirone good, but high toxicity profile,
  used in patients with bad heart disease
  (significant systolic dysfunction, hypertension
  with LVH)
• Toxicity pulmonary, photosensitivity, thyroid
  dysfxn, corneal deposits, ECG changes, Liver
  dysfxn

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Rate Control

• RVR causes
• Symptoms and Hemodynamic Instability
• Tachycardia mediated cardiomyopathy
• Rate control
• Achieved by slowing AV conduction (beta blockers,
  calcium channel blockers, dig, amio)
• Digoxin only in hypotension and Heart Failure
• Amiodirone rarely but effective

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AFFIRM trial

• Heart Rate Targets rest and exercise
• Resting lt80/min
• 24 hr avg of lt100/min and no rate gt110 percent of
  predicted max for age
• lt110 beats/min in six minute walk
• Essential component is absence of activities
  during normal activities or exercise.

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Rate vs. Rhythm control

• AFFIRM and RACE trials Two conclusions
• Embolic events are equal and occur with low INR
  levels or after warfarin stopped
• Trend toward a lower incidence of the primary end
  point (mortality and event free survival) in rate
  control. There was no difference in the quality
  of life or functional status.
• ? Rate control is therefore preferred in all
  except
• Persistent symptoms, Inability to attain rate
  control, patient preference
• Also consider cardioversion for young healthy
  patients and first episodes with low risk of
  recurrence. Antiarrythmics usually not used
  following cardioversion.

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Anticoagulation during reversion to NSR

• AF gt48 hrs or unknown
• Anticoagulate for gt3 weeks, INR 2-3
• Or, TEE to eval for clots in LA Appendage if no
  clots convert.
• After, anticoagulate for 4 weeks with warfarin
  stunned atrium
• Consider chronic anticoagulation for those with
  high risk for reversion.

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Why chronic anticoagulation once cardioverted and
NSR?

• Pts at high risk for recurrence asymptomatic
  periods of short AF produce thrombi then
  embolize (90 of recurrent episodes not noticed)
• Some Pts with AF that is not associated with
  reversible cause are at high risk for emboli
  anyway (aortic plaque, LV systolic dysfxn)

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Anticoagulation in Chronic AF

• Stroke associated with AF is 3-5/year without
  anticoagulation
• Many factors determine ASA vs. warfarin
• Estimated risk of stroke is determined with a
  CHADS2 score and therapy determined with this
  scale of 1-6. (CHF, HTN, Age, DM, Secondary
  prevention)
• 0 get ASA because of 0.5/year w/o coumadin
• 1-2 intermediate risk
• gt or 3 warfarin
• P.S. ASA usually added to warfarin

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New Onset Atrial Fibrillation

• ER reversion - lt48 hrs, uncomplicated, low risk
  convert them and get them out.
• Safe and cost effective
• Hospitalization Admission Indications
• Rule out MI ST elevation/depression
• Treating associated medical problem
• Elderly patients
• Underlying heart disease with hemodynamic effects
  from AF or could be at risk for complication from
  therapy

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New Onset Contd.

• Search for cause fixing the cause may cause
  reversion by itself.
• If fixing a cause start heparin as an inpatient
  and bridge to coumadin for 3-4 weeks in
  anticpation of cardioversion if pt. doesnt
  spontaneously convert
• Indications for immediate cardioversion
• Active ischemia
• Hypotension
• Severe HF

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New Onset contd.

• Start rate control mild to moderate symptoms
• Beta blockers, Calcium channel blockers (
  verapamil and diltiazem), and digoxin
• Digoxin good for 2nd line or in HF
• Can use both BB and Calcium Ch. Blocker together.
• Elective Cardioversion
• Immediate if less than 48 hrs and no cardiac
  abnormalities
• Delayed anticoagulate first 4 weeks.
• Duration gt48 hrs, assoc. mitral valve disease or
  Cardiomyopathy/HF, prior stroke/TIA

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