Atrial Fibrillation


  • Uncoordinated atrial activation with atrial mechanical dysfunction.
  • Major risk of cardioembolism causing ischaemic stroke.
  • Assess with risk score.


  • Atrial fibrosis, loss of atrial muscle mass.
  • Increased automaticity or multiple re-entrant wavelets.
  • Atrial ‘rate’ of AF is 400–600/min, but it is the ventricular response that matters.
    • Ventricular rate held in check by AV node at <200/min, slows with age and conduction disease.
    • An accessory bundle (WPW) can allow faster rates to conduct AV causing VF.


  • ↑ HR shortens diastole and limits LV filling and coronary perfusion. LV filling may already be compromised by loss of atrial systole.
    • Rate control with drugs, treat failure and DC shock if needed.
    • Impaired LV function or mitral stenosis makes things much worse!


  • Asymptomatic.
  • Palpitations, dyspnoea, chest discomfort.
  • Cardioembolic stroke, mesenteric emboli, limb emboli, dyspnoea.
  • Fatigue and worsening heart failure, syncope, dizziness.
  • ↓BP with fast/slow AF, irregularly irregular pulse.
  • Pulse deficit.
  • Murmurs suggesting valve disease, signs of thyroid disease, hypertension.


  • Ischaemic / valvular / rheumatic / hypertensive heart disease / cardiomyopathy / post cardiac surgery / thyrotoxicosis / alcohol – acute binge or chronic / sick sinus syndrome / congenital heart disease / pulmonary embolism / pneumonia / sarcoidosis / amyloidosis  / haemochromatosis / lone AF (idiopathic) / pericarditis / myocarditis.


    Classification of atrial fibrillation

    ● Persistent: lasts >7 days.
    ● Paroxysmal: 2+ episodes self-terminating lasting <7 days.

    ● Permanent: lasts >1 year and fails to cardiovert.
    ● Lone AF: aged <60 y, no HTN, normal echo, no risk factors.


  • Bloods
    • FBC – ↓Hb
    • ↑WCC – sepsis
    • U&E
    • Mg, Ca, K
    • TFT – thyrotoxicosis
    • LFTs – alcohol, haemochromatosis.
  • CXR
    • cardiomegaly
    • pulmonary oedema
    • infection
    • post cardiac surgery effusion
  • Troponin
    • ↑with ACS or myocarditis
    • minor rise with DC shock
  • ECG
    • Absent ‘P’ waves – no organised atrial activity
    • Fibrillatory waves that vary in amplitude, shape and timing
    • QRS complexes which are irregularly irregular
    • Aberrantly conducted AF: wide complex and fast but irregular.
    • Pre-excited AF: QRS 160–300/min and slurred up or down stroke of delta waves seen giving wide complex appearance but very irregular; the irregularity means that it is not VT.

Dangerous if it conducts to ventricles at 1:1 and can precipitate VT/VF. This depends on the character of the accessory pathway. If there are RR intervals <260 ms this is considered unsafe and needs inpatient cardiology review for ablation. If unstable simply DC cardiovert.

Capturing PAF

  • 24 h tape in those with suspected asymptomatic episodes or symptomatic episodes less than 24 h apart.
  • Use an event recorder ECG in those with symptomatic episodes more than 24 h apart. Some may use 7 day tape.


  • Transthoracic echocardiogram
    • assess LV function
    • valve disease
    • LA size
  • Anticoagulation rarely depends on the echo.
  • Transoesophageal echocardiogram
    • closer inspection of valves
    • mitral disease
    • ASD
    • endocarditis
    • LA thrombus may be seen and can help assess risk of thromboembolism

Coronary angiography

  • If IHD suspected.

Atrial Fibrillation anticoagulation risk assessment

  • CHA2DS2VaSc score, assesses stroke risk in those with AF.
    • Adjusted annual stroke risk by score:
      • (0) 0% / (1) 1.3% / (2) 2.2% / (3) 3.3% / (4) 4.0% / (5) 6.7% / (6) 9.8% / (7) 9.6% / (8) 6.7% / (9) 15.2%
  • HAS-BLED score, assesses bleeding risk.
    • A score of 3 or more indicates increased 1 year bleed risk on anticoagulation sufficient to justify caution or more regular review.
    • Risk is for intracranial bleed, bleed requiring hospitalisation or a haemoglobin drop >2 g/L or that needs transfusion.


For all:

  • ABC, high flow oxygen as needed.
  • IV fluids cautiously if at all in LVF or fluid overloaded.
  • Start treatment dose LMWH in all with AF and not anticoagulated with no contraindications.
  • Look for and treat any cause: chest infection, thyrotoxicosis, ACS, PE, sepsis, MI/ACS, pulmonary oedema, PE, alcohol excess or withdrawal.

AF and unwell:

  • Remember AF and fast AF can be a response to an infective, inflammatory or metabolic/toxic cause.
  • Treatment must balance to focus on treating the underlying cause as well as using rate control drugs.
  • Look for causality.
  • If fast AF is causing compromise: ↓? BP, LVF, angina then DC cardioversion, which may be done without anticoagulation, but start LMWH [NICE 2014].
  • If not severely compromised consider
    • AMIODARONE 150–300 mg IV, 30–60 min via a large bore cannula or preferably a central line.
      • Any deterioration then emergency DC cardioversion.
      • Further amiodarone infusions require a central line.
    • Alternatives include DIGOXIN loading or a BETA-BLOCKER.
    • Consider cardioversion if arrhythmia is less than 48 h, and start rate control if AF duration >48 h or is uncertain. Anticoagulate both.
    • Consider Bisoprolol, Atenolol or Metoprolol (avoid Sotalol) especially if angina or hypertension.
    • Digoxin can be loaded (check not on it already) useful especially if in LVF
      • DIGOXIN 500 mcg PO/slow IV over 1 h  
      • Then 250–500 mcg PO/slow IV 6 h later.
      • Digoxin slows resting rate and is an inotrope and best for those with CCF or a sedentary life. Reduce dose with renal failure.
      • Rhythm control AF >48 h must wait until anticoagulated for a minimum of 3 weeks.

AF and well

  • Ventricular rate 60–120/min and haemodynamically well. Determine and manage cause. The question will be between rate control – slowing the AF – or rhythm control by trying to chemically or electrically cardiovert the patient to sinus rhythm and maintaining it.
  • Assess need for anticoagulation and if needed start LMWH/UFH acutely or DOAC.

Rate control

  • Consider oral Beta-blocker or rate limiting CCB.
  • Digoxin may be considered if sedentary lifestyle.
  • Avoid Amiodarone long term as side effects significant.
  • Rhythm control – repeated attempts to remain in SR – DC cardioversion

Anticoagulation and cardioversion

  • DC
    • You can electrically or chemically cardiovert immediately if you can be certain that AF duration is <48 h or a TOE shows that there is no LA appendage thrombus, or it is clinical indicated due to instability.
    • For those where the above is not the case, Start LMWH or IV Heparin immediately and continue for at least 3 weeks.
    • If elective cardioversion is planned, then anticoagulate for 3 weeks before and at least 3 weeks after.
  • Chemical cardioversion
    • Consider Amiodarone (limited duration) or Dronedarone.
    • Flecainide can be used if LV function normal and no significant IHD.

Aim to get SR (rhythm control): when patient is unstable and SR would improve haemodynamics, in younger symptomatic patients or those with stroke or cardiomyopathy. Overall prognosis, however, is the same.

Specific scenarios

Pre-excited AF and WPW syndrome

  • Use IV PROCAINAMIDE / IV AMIODARONE IV Sotalol or IV Flecainide
  • If unstable, then immediate DC cardioversion.

Avoid digoxin, beta-blockers and Verapamil or Diltiazem in pre-excited AF. They may increase risk of VF.

  • Assess for anticoagulation.

Prevention and management of postoperative AF

  • With cardiothoracic surgery reduce postoperative AF by offering either amiodarone, a standard beta-blocker (not sotalol), or a rate-limiting calcium antagonist.
  • DO NOT offer digoxin.
  • Continue any pre-existing beta blockade.
  • Postop, offer a rhythm based strategy.
    • For postop AF, use appropriate antithrombotic therapy and correct identifiable precipitants (U&E, low SpO2) [NICE 2014].

Atrial flutter

  • Also needs rate control, risk assessment and anticoagulation.
  • Beta blockade, diltiazem or digoxin for rate control.
  • Cardioversion should be considered with same assessment and anticoagulation as for AF.
  • AMIODARONE is useful for rapid rate control.

Remember – Anticoagulation consideration in all with AF, atrial flutter or PAF. Determine CHA2DS2VaSc score and HAS-BLED score and assess risk/benefits of anticoagulation.

Other considerations

  • Control hypertension, review need for aspirin or NSAIDs, stop/reduce alcohol.
  • Do not avoid anticoagulation purely on ‘risk of falls’. Quantify risk and intervene to reduce falls where possible.
  • Anticoagulate
    • CHA2DS2VaSc > 1 in men
    • >2 in women.
    • If non-valvular AF (those severe MS or AS or with a metal valve must have warfarin or LMWH) then consider Warfarin or a DOAC (Apixaban, Dabigatran or Rivaroxaban, etc.).
    • High CHA2DS2VaSc score needs urgent commencement on LMWH or a DOAC or Warfarin.
    • If anticoagulation contraindicated or not acceptable then consider cardiology referral for Left atrial appendage occlusion.

Bridging anticoagulation

  • Interruptions in anticoagulation can increase embolic risk.
  • It is common to give LMWH bridging in the perioperative period but this may lead to risk of bleeding.
    • A recent study in the NEJM has looked at this.
      • The study excluded those with mechanical heart valves, stroke/TIA/systemic embolization within 12 weeks, major bleeding within 6 weeks, renal insufficiency, ↓? platelets or planned cardiac, brain or spinal surgery were excluded.
      • The conclusion was that bridging is not warranted for most AF patients with CHA2DS2VaSc scores of <4, for low-risk procedures.
      • This study must be interpreted along with local expert guidance balancing the risk of peri-procedure bleeding and embolic risk.

See also

Screen Shot 2018-01-02 at 14.59.28.png


Presentation below by Dr Dave Sharman (Cons Cardiologist – click the pic!)

Screen Shot 2018-01-02 at 15.20.56.png


Powered by

Up ↑

You have successfully subscribed to the newsletter

There was an error while trying to send your request. Please try again.

Critical Care Northampton will use the information you provide on this form to be in touch with you and to provide updates and marketing.
%d bloggers like this: