Background

This is designed as a quick guide to the management of this common ITU condition. Click here for the original NICE guidance for AF

New Onset AF (NOAF)

  • Usually prequelled with some previous risk factors:
    • Age
    • Poor LV function
    • LA dilatation
    • Thyroid disease
    • Alcohol consumption
    • Hypertension

Atrial fibrillation with fast ventricular rate

  • Cardiac
    • Acute LVF
    • ACS
    • Cardiomyopathy
  • Non-cardiac
    • Increase in sympathetic drive
    • Increased conductivity of the AV node leading to fast irregular atrial activity. Causes include:
      • Sepsis
      • Head injury
      • PE
      • Acute respiratory failure
      • Metabolic derangement
      • Thyroid disease
      • TIA/CVA
      • Major haemorrhage

Aims of Treatment in ITU

  • Rate limit or Cardiovert
  • Adequately assess risk of acute stroke
  • Decide regarding acute anticoagulation
    • Many critical care patients have potential absolute or relative contra-indications to anticoagulation, such as being post-operative, needing invasive lines or having DIC which should be taken into consideration.

 

1. Pharmacological Rate Control

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  • First line therapy (according to NICE) and is the more common method of acute AF control.
    • Reduces stroke risk
    • Often the ongoing longer term management for these patients’ AF
    • Many patients will ‘self cardiovert’ back to sinus rhythm in the background, as the sympathetic process, coupled with AVN transmission inhibition occurs due to rate limitation.
    • The aim is to reduce the heart rate to less than 120  in an attempt to prevent cardiac decompensation and associated sequalae such as Type 2 MI.

Options

Beta Blockade

  • Esmolol
    • IV 25-200mcg/kg/min – trial only
    • If rate reduction is achieved with CVS stability then a longer acting BB can be used
    • If BP drops then another class of agent should be tried
  • Metoprolol
    • IV bolus, up to 5mg (at 1-2mg/min)
    • Repeated up to 15mg
  • Bisoprolol
    • PO/NG 1.25-10mg OD

Digoxin

  • Can rate limit or cardiovert
    • Loading dose 500mcg at 6 hour intervals
    • Maximum 1.5mg in 24hours
    • Maintenance with 125-250mcg OD

Amiodarone

  • Can act to both rate limit or primarily cardiovert
    • IV 300mg over 1 hour through central line or good sized peripheral cannula, ideally ACF
    • Followed by 900mg over 23 hours via a central line only due to the risk of vessel damage
    • Occasionally, the initial infusion is enough to treat the issue

Rate limiting Ca2+ channel blockade

  • Diltiazem
    • PO/NG 60mg TDS
    • Increased to maximum of 360mg OD
  • Verapamil
    • PO 40-120mg TDS
    • IV slow injection 5-10mg

 

2. Electrical Cardioversion

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  • Reserved as first line for haemodynamically compromised patients
    • Cardiac ischaemia
    • Persistently low BP despite fluid management
  • It can also be used in younger patients deemed low stroke risk where the AF is NOAF (i.e. less than 48 hours)
  • It can also be used in those where rate-controlled strategies have not been successful

Housekeeping

  • Explain to patient and consent if appropriate about procedure
  • Assemble team
  • Ensure airway competent person is present
  • Assess for aspiration risk, if high then intubation should be considered
  • Apply cardioversion pads from defibrillator to patients’ chest appropriate positions
  • Ensure good IV access and if required, sedate the patient with 1-5mg of Midazolam or low dose Propofol
  • Using a manual defib, ‘sync’ the defibrillator to apply a synchronised shock. How much energy is a controversial arena! Here is a nice discussion for you, where different energy levels for shocking AF are discussed. It also depends whether you are using mono or biphasic machines.
    • first shock 200J
    • second 300J
    • third 360J
  • Try to record the change in rhythm on the defib printer if possible

 

3. Chemical Cardioversion

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  • Amiodarone IV – (See doses above)
  • Flecainide
    • IV 2mg/kg over 10-30 minutes (max 150mg)
    • Followed by infusion of 1.5mg/kg/hour for 1 hour, then 100-250mcg/kg/hour for upto 24 hours
    • DO NOT offer Flecainide to patients with evidence of structural heart disease

4. Electrolyte Correction

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  • K+ >4.5
  • Magnesium >1

 

5. Anticoagulation

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Acute

Most people with AF pre-admission to ITU should have already been risk assessed by either there GP or specialist.

  • Acute anticoagulation is considered for those with a significant stroke risk
    • LV thrombus
    • Previous stroke
    • Those with concurrent advantages of anti-coagulation e.g. PE, MI
  • Not needed in those with:
    • CHA2DS2VASC of 0 for men or 1 for women
    • <48hrs NOAF
  • Needed if:
    • Stable sinus rhythm is not successfully restored within the same 48-hour period following onset of atrial fibrillation and have an appropriate CHADS 2 AF / Stroke risk score
    • Risk factors indicating a high risk of atrial fibrillation recurrence

Long term

  • Anticoagulation risk should be assessed in all AF patients
  • Current NICE guidelines (2014) suggest it should be considered in all patients with:
    • Symptomatic or asymptomatic paroxysmal AF
    • Persistent or permanent atrial fibrillation or those with a continuing risk of arrhythmia recurrence after cardioversion back to sinus rhythm.
  • The CHA2DS2VASC and HASBLED scoring systems are good for assessing stroke and bleeding risks respectively.
  • HASBLED takes into account:
    • Uncontrolled hypertension
    • Significant renal and liver disease
    • Bleeding risk (such as relevant medications and labile INRs)
    • Alcohol consumption
  • On discharge from ITU/HDU, obtain appropriate follow up whilst an inpatient for ongoing management and stroke risk.

Drug Choices

Acute treatment dose

  • Low Molecular Weight Heparin
    • Clexane 1.5mg/kg or Dalteparin

Long-term treatment dose

  • Warfarin
  • NOAC
    • Apixaban, Dabigatran, Rivaroxaban
    • Usually used in older patients 65-75, those with prior CVA or TIA, Hypertension, Diabetes or Symptomatic heart failure
    • Do not offer Anti-platelets

 

Sticker It!!

Below is a sticker designed to be placed into the notes of your patient. The point is to ensure that NICE guidelines are angered to, and acts as an aide memoire for those less familiar with this condition.

Click to download word doc.

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Resources to look at

 

Concept and piece original: Dr David Popple (Cons ITU and Dr Andrew Redfern Resp/ITU registrar)

Senior editor: Dr Jonny Wilkinson