Atrial fibrillation and atrial flutter

• Atrial fibrillation (AF)

  Chaotic, irregular atrial rhythm at 300–600bpm; the AV node responds intermittently, hence an irregular ventricular rate
• Atrial fibrillation

  Cardiac output drops by 10–20% as the ventricles aren't primed reliably by the atria
• Atrial fibrillation is common in the elderly (≤9%)
• Atrial fibrillation

  The main risk is embolic stroke
• Warfarin


  Reduces the risk of embolic stroke from 4% to 1% per year
• Diagnosing atrial fibrillation

  1. Do an ECG on everyone with an irregular pulse

  2. Consider 24h ECG if dizzy, faints, palpitations, etc.
• Causes of atrial fibrillation

  • Heart failure/ischaemia
  • Hypertension
  • MI (seen in 22%)
  • PE
  • Mitral valve disease
  • Pneumonia
  • Hyperthyroidism
  • Caffeine
  • Alcohol
  • Post-op
  • K+
  • Mg2+
  • Cardiomyopathy
  • Constrictive pericarditis
  • Sick sinus syndrome
  • Lung cancer
  • Atrial myxoma
  • Endocarditis
  • Haemochromatosis
  • Sarcoid
• Lone atrial fibrillation

  No cause found
• Symptoms of atrial fibrillation

  • Asymptomatic
  • Chest pain
  • Palpitations
  • Dyspnoea
  • Faintness
• Signs of atrial fibrillation

  • Irregularly irregular pulse
  • Apical pulse rate greater than radial rate
  • Variable intensity of 1st heart sound
  • Signs of left ventricular failure
• Examine the whole patient: atrial fibrillation is often associated with non-cardiac disease
• ECG findings in atrial fibrillation

  • Absent P waves
  • Irregular QRS complexes
• Tests for atrial fibrillation

  • ECG
  • Blood tests: U&E, cardiac enzymes, thyroid function
  • Echocardiogram to look for left atrial enlargement, mitral valve disease, poor LV function, and other structural abnormalities
• Acute atrial fibrillation (within 48 hours)

  1. If very ill or haemodynamically unstable: O2, emergency cardioversion, or IV amiodarone if cardioversion unavailable

  2. Treat associated illnesses (e.g. MI, pneumonia)

  3. Control ventricular rate: 1st-line verapamil or bisoprolol, 2nd-line digoxin or amiodarone

  4. Start full anticoagulation with LMWH, to keep options open for cardioversion even if the 48h time limit is running out

  5. If the 48h period has elapsed, cardioversion is OK if transoesophageal echo thrombus-free
• Cardioversion regimen


  O2, ITU/CCU, GA or IV sedation, monophasic 200J 360J 360J (biphasic; 200J)
• Pharmacological cardioversion

  1. Amiodarone IV (5mg/kg over 1h then ~900mg over 24h via a central line) or PO (200mg/8h for 1wk, 200mg/12h for 1wk, 100–200mg/24h maintenance)

  2. Flecainide IV (2mg/kg over 10–30min, max 150mg) or PO (300mg stat), monitor ECG
• Chronic atrial fibrillation


  Main goals are rate control and anticoagulation
• Rate control

  At least as good as rhythm control, but rhythm control may be appropriate if symptomatic, younger, presenting for 1st time with lone AF, or AF from a corrected precipitant
• Rate control in chronic atrial fibrillation

  1. Beta-blocker or rate-limiting calcium channel blocker are 1st choice

  2. If this fails, add digoxin, then consider amiodarone

  3. Digoxin as monotherapy is only OK in sedentary patients

  4. Don't give beta-blockers with diltiazem or verapamil without expert advice (bradycardia risk)

  5. Don't get fixated on a single figure to aim for, dialogue with patients to find what works best and allows desired exercise levels
• Rhythm control in chronic atrial fibrillation

  1. If cardioversion is chosen, do echo 1st; pre-treat for ≥4wks with sotalol or amiodarone if there is risk of cardioversion failure

  2. Pharmacological cardioversion: flecainide is 1st choice if no structural heart disease, IV amiodarone if structural heart disease

  3. AV node ablation, maze procedure, pacing, and pulmonary vein ablation are options to ask about
• Paroxysmal atrial fibrillation

  'Pill in the pocket' (e.g. sotalol or flecainide PRN) may be tried if infrequent AF, BP >100mmHg systolic, no past LV dysfunction
• Atrial flutter


  Continuous atrial depolarization (e.g. ~300/min, but very variable) produces a sawtooth baseline ± 2 : 1 AV block (as if SVT at, e.g. 150bpm)
• Diagnosing atrial flutter

  Carotid sinus massage and IV adenosine transiently block the AV node and may unmask flutter waves
• Treating atrial flutter

  1. Cardioversion may be indicated (anticoagulate before)

  2. Anti-AF drugs may not work—but consider amiodarone to restore sinus rhythm, and amiodarone or sotalol to maintain it

  3. Aim to control rate as in atrial fibrillation; if the IV route is needed, a beta-blocker is preferred

  4. Rarely, cavotricuspid isthmus ablation
• Chronic AF

  Main goals in managing permanent AF are rate control and anticoagulation
• Rate control is at least as good as rhythm control

  But rhythm control may be appropriate if symptomatic or CCF, younger, presenting for 1st time with lone AF, or AF from a corrected precipitant
• CHA2DS2-VASc SCORE 58

  • Score 1 point for each of: heart failure, diabetes, hypertension, vascular disease, aged>65, female; AND 2 points for: age ≥75, or prior TIA, stroke/thromboembo- lism. A score of 2 = an annual stroke risk of ~2.2%.

  • If the score is 1 or more (or 2 or more if older) consider oral anticoagulation. Bleeding risk can also be calculated, eg HEMORR2HAGES or HAS-BLED scores. See also CHADS2 score
• Anticoagulation

  See BOX 1
• Acute AF management

  1. Use heparin until full risk assessment for emboli is made

  2. If AF started <48h ago and elective cardioversion is planned, ensure ≥3wks of therapeutic anticoagulation before cardioversion (trans-oesophageal-guided cardioversion is also an option if >48h)

  3. Use warfarin (target INR: 2.5; range 2–3) if risk of emboli high (past ischaemic stroke, TIA or emboli; 75yrs with BP, DM; coronary or peripheral arterial disease; evidence of valve disease or LV function/CCF—only do echo if unsure)

  4. Use no anticoagulation if stable sinus rhythm has been restored and no risk factors for emboli, and AF recurrence unlikely (ie no failed cardioversions, no structural heart disease, no previous recurrences, no sustained AF for >1yr)
• Rate control

  1. First choice: β-blocker or rate-limiting Ca2+ blocker

  2. If this fails, add digoxin

  3. Then consider amiodarone
• Digoxin as monotherapy in chronic AF is only OK in sedentary patients
• Chronic AF

  Anticoagulate with warfarin and aim for an INR of 2–3.54
• Don't give β-blockers with diltiazem or verapamil without expert advice (bradycardia risk)
• Don't get fixated on a single figure to aim at: dialogue with patients tells what works best and allows desired exercise levels, e.g. <90 at rest and on exertion 200–age (yrs) if ambulatory
• Less good alternative to warfarin

  Aspirin ~300mg/d PO—eg if warfarin contraindicated or at very low risk of emboli (<65yrs, and no hypertension, diabetes, LV dysfunction, LA size, rheumatic valve disease, MI, or past TIA)
• Rhythm control

  1. If cardioversion is chosen, do echo 1st

  2. Pre-treat for ≥4wks with sotalol or amiodarone if there is risk of cardioversion failure

  3. Pharmacological cardioversion: flecainide is 1st choice if no structural heart disease (IV amiodarone if structural heart disease)

  4. AV node ablation, maze procedure, pacing, and pulmonary vein ablation are options to ask about
• Contraindications to warfarin in AF

  • Bleeding diathesis
  • Platelets <50≈109/L
  • BP>160/90 (consistently)
  • Compliance issues around dosing or INR monitoring
  • Patient choice, after risks discussed
• Factors that may be considered contraindications to warfarin but are less evidence-based

  • Age 75–80yrs old
  • Frequent falls
  • On NSAIDS
  • Past intracranial bleeds
  • Hb
  • Polypharmacy
• Paroxysmal AF 'pill in the pocket'

  May be tried if: infrequent AF, BP >100mmHg systolic, no past LV dysfunction
• the CHADS2 score

  Congestive heart failure

  Hypertension: blood pressure consistently

  above 140/90mmHg (or treated hypertension on medication)

  A Age≥75yrs

  D Diabetes mellitus 1 S2 Prior stroke or TIA or thromboembolism