Atrial Fibrillation

by | Nov 26, 2017

Details on Atrial Fibrillation, which can be considered in context of palpitations, a cause of stroke, or undifferentiated dizziness/faint/fit/funny turn, or as a precursor to talking about anticoagulants. 

 

Features of history in AF

  • Irregularly irregular pulse of 160-180
  • Persistent vs paroxysmal vs permanent (chronic)

Causes of AF

  • MI (15%)
  • Mitral valve disease
  • Thyrotoxicosis
  • Hypertension
  • Pericarditis
  • Cardiomyopathy
  • Chronic alcohol dependance
  • Alcohol binge
  • No cause found in 12%

Complications of AF

  • 5% chance per annum of embolic episodes
  • 5x risk of CVA overall

Two main options for AF control

  • Rate
  • Rhythm

Urgent control of severe/compromised AF

  • Cardioversion if episode less than 48 hrs (though 24hrs would be safer)
  • Electrical vs pharmacological cardioversion

IV Cardioversion of AF pharmacologically

  • Amiodarone 150-300mg IV infusion over 20min – 2hrs
  • Flecainide 2mg/kg IV (max 150) over 30 min

Oral Pharmacological Cardioversion of AF

  • Amiodarone 200-400mg tds 1 week then BD 1 week then 100-200mg daily ongoing
  • Flecainide 50-100mg PO tds

Electrical cardioversion for AF

  • DC shock 100-300J
  • Atrial Flutter requires 50J

Urgent Rate Control in AF

  • Metoprolol 5mg IV at 1mg / min repeated at 5 min intervals, up to 20mg
  • Verapamil 1mg/min IV up to 15mg

Acute Management of rate control in AF

  • Digoxin 0.5 1mg immediately then 0.25-0.5mg every 4-6 hrs; to max 1.5-2
  • Verapamil 1mg/min IV (max 15mg)

Routine rate control of AF

  • Atenolol 25-100mg daily
  • Metoprolol 25-100mg BD
  • Diltiazem 180 – 360mg daily
  • Verapamil SR 160-480mg daily
  • Digoxin 62.5ug – 250ug daily

Routine Rhythm Control in AF

  • Flecainide 50-100mg BD
  • Sotalol 40-169mg BD

Anticoagulation in AF

  • 3 weeks min
  • Enoxaparin 1mg/kg SC BD
  • Warfarin
  • Rivaroxaban
  • If there is AF for more than 48 hrs before presentation

CHADS2

  • C = congestive heart failure
  • H = HTN > 160/90
  • A = age > 65
  • D = diabetes
  • S = stroke

What are the components of CHA2DS2VASC?

  • C = CHF = 1
  • A = age = 75 = 2 points
  • D = diabetes = 1
  • S  = stroke = 2 points
  • V = vascular disease = 1
  • A = age > 65 = 1 point
  • Sc = sex category female = 1 point

What CHADS2VASC score do you start treatment?

  • Start oral anticoagulant if score >= 2
  • No anticoagulation necessary if score = 0

HASBLED

  • H = HTN > 160
  • A= abnormal liver or renal
  • S = stroke
  • B = bleeding history or predisposition
  • L = labile INR (< 6 of 10 in range)
  • E = elderly
  • D = drugs (anti-platelets, alcohol, NSAIDs)

What to do if CHADS2 score is 

  • 0 = none or aspirin
  • 1 = oral AC or aspirin
  • 2 = oral AC

Features if Digoxin toxicity

  • Anorexia
  • Nausea
  • Vomiting
  • Fainting
  • Palpitations
  • Tachycardia
  • Blurred vision

Investigations for digoxin toxicity

  • Serum digoxin
  • ECG shows atrial tachycardia with 2:1 lock

What is the effect of thyroid disease on anticoagulation

  • More hypercoaguable and hypofibrinolytic state
  • Shift towards hyperstasis
  • Increased risk of stroke