ATRIAL FIBRILLATION/FLUTTER - 1B

DEFINITION

Classified based on pattern of episodes:

  • Paroxysmal AF
    • Episodes lasting >30 seconds but less than 7 days
    • Self-terminating + recurrent
  • Persistent AF
    • Episodes >7 days
    • Spontaneous termination unlikely to occur after 7 days
    • Needs electrical/pharmacological cardioversion for termination
  • Permanent AF
    • AF that fails to terminate after cardioversion or
    • That is terminated but relapses within a day or
    • Long-standing aka accepted permanent AF (usually >1 year) where cardioversion not indicated or attempted

AF is an arrhythmia

  • Irregular, disorganised electrical activity in atria
  • Most common sustained cardiac arrhythmia
  • Irregularly irregular ventricular pulse + loss of association between cardiac apex beat + radial pulsation

PATHOPHYSIOLOGY


  • In most, due to cells rapidly firing impulses at junction of pulmonary veins in left atrial (LA) musculature → disorganised atrial depolarisation + ineffective atrial contractions
  • AVN receives more electrical impulses than it can conduct → irregular ventricular rhythm→ loss of active ventricular filling →
    • stagnation of blood in atria → thrombus formation + risk of embolism → increasing stroke risk
    • reduction in CO esp. during exercise → HF

AETIOLOGY

  • Most have identifiable cause
  • Lone AF where no obvious cause + all investigations normal happens in small % of AF → but more common in paroxysmal AF Px


  • Most common causes of AF:
    1. Ischaemic heart disease aka coronary heart disease e.g. MI
    2. Hypertension (can lead to LV hypertrophy)
    3. Valvular heart disease
    4. Hyperthyroidism

Other factors thought to cause/associated with AF:

  • Cardiac or valve conditions e.g.
    • HF
    • Rheumatic heart disease
  • Non-cardiac conditions e.g.
    • Drugs e.g. bronchodilators
    • Acute infection - ether resp. (e.g. chest infection) or systemic cause
    • Electrolyte depletion - systemic cause
    • Lung cancer - resp. cause
    • Pulmonary embolism - resp. causes
    • DM
    • Thyrotoxicosis - systemic cause
  • Dietary + lifestyle factors e.g.
    • Excessive caffeine, alcohol - systemic causes
    • Obesity

INVESTIGATIONS

COMPLICATIONS

  • Stroke & thromembolism incl. peripheral thromboembolism - main complication
  • HF - commonly linked with AF
    • HF can occur due to disorganised electrical conduction in atria → ineffective ventricular filling → pushing already compromised ventricle into failure → ↓CO further
  • Tachycardia-induced cardiomyopathy & critical cardiac ischaemia
    • Both conditions due to persistently ↑ ventricular rate in uncontrolled AF
  • ↓ quality of life
    • AF → ↓exercise tolerance & impaired cognitive function

  • Do manual pulse palpation for presence of irregular pulse


  • If irregular pulse whether symptomatic or not → ECG


    • If AF present:
      - no P-waves
      - chaotic baseline
      - irregularly irregular ventricular rate (variability in R-R intervals)

    image



    • Ventricular rate 160-180 bpm or ↓ esp. in asymptomatic Px
    • Ventricular complexes look normal unless ventricular conduction defect

  • If paroxysmal AF suspected + AF not detected on standard ECG → 24 hour ambulatory ECG

CLINICAL FEATURES

  • Irregular pulse with/without:


    • dyspnoea
    • palpitations
    • chest discomfort
    • syncope/dizzy
    • ↓exercise tolerance, malaise, polyuria
    • potential complication of AF e.g.
      • stroke
      • transient ischaemic attack
      • HF

  • Absence of irregular pulse makes AF unlikely but still presence of it isn't reliable indicator of AF either


  • Suspect paroxysmal AF if symptoms episodic last <48 hours

DDx

  • Atrial flutter
    • saw-tooth pattern of regular atrial activation on ECG
    • AF can alternate with atrial flutter
    • atrial flutter may develop into AF
    • atrial flutter might happen during treatment of AF with ani-arrhythmic drugs
  • Sinus tachycardia
    • sinus rhythm with >100bpm
  • Supraventricular tachycardia e.g.
    • atrial tachycardia, atrioventricular nodal re-entry tachycardia
  • Thyroid function tests (TFTs)
    • for underlying causes of AF e.g. thyrotoxicosis
  • FBC
    • anaemia might worsen HF
    • sepsis?
  • U&E
    • electrolyte disturbance can worsen AF
    • urea is waste product metabolism excreted by kidneys in urine; ↓urea excretion = kidney disease indicator
    • electrolytes; abnormal serum K+ levels can worsen arrhythmias esp. if Px taking or going to take digoxin
  • LFTs
  • Coagulation screen - pre-warfarin
  • CXR
    • may indicate cardiac structural causes of AF e.g. mitral valve disease or HF
    • do if suspect lung pathology e.g. pneumonia, lung cancer)
  • Echocardiogram - transthoracic - in some:
    • if considering cardioversion
    • if ↑risk of underlying structural (e.g. ❤ murmur) or functional (e.g. HF) heart disease that will influence management e.g. which anti-arrhythmic
  • CT or MRI - if stroke/TIA suspected

MANAGEMENT

  • SUMMARY of MANAGEMENT FOR FIRST/ONSET NEW + PAROXYSMAL AF - NICE:
    • Admit/refer if severe symptoms
      • rapid pulse >150bpm
      • hypotension
      • syncope, dizzy
      • ongoing chest pain
      • increasing dyspnoea
    • Admit/refer if severe complications
      • stroke
      • TIA
      • acute HF
    • ID + manage underlying causes
    • Treat arrhythmia
      • rate control (BB or CCB)
      • refer for rhythm control/cardioversion
      • assess stroke risk using CHA2DS2VASc
      • assess if anticoagulation appropriate i.e. if stroke risk high + use HAS-BLED for bleeding risk
      • follow up
      • advice/info on AF etc. + support groups

TREATMENT DETAILS

  • NICE TREATMENT - FOR FIRST/NEW PRESENTATION OF AF:

  • RATE control treatment - most Px → BB (LOL) or rate-limiting CCB (verapamil/diltiazem)


    • Whether BB or CCB depends on CI (❌), e.g. BB ❌ in asthma vs. CCB ❌ in co-existing HF

    • ❌ sotalol - don't prescribe in GP for RATE control (can be life-threatening) - only specialists can prescribe for RHYTHM control


    • Digoxin monotherapy for non-paroxysmal sedentary Px

    • Follow up to assess tolerance + review symptom control, HR, BP


  • Refer to cardiologist for RHYTHM control (CARDIOVERSION) for:
    • New onset AF
    • AF with reversible cause e.g. chest infection
    • If have HF mostly caused/worsened by AF
    • If have atrial flutter + restoring sinus rhythm is possible
  • Rhythm control used by specialists:
    • Electrical cardioversion → if persisted for >48 hours
    • Pharmacological cardioversion → e.g. sotalol or amiodarone

  • Anticoagulate Px (warfaring/NOAC) BEFORE cardioversion


    • as risk of embolism leading to stroke is highest the moment Px switches from AF to sinus rhythm in cardioversion - as thrombus formed in fibrillating atrium can suddenly be pushed out when sinus rhythm restored
    • at least 3 weeks before and some time after cardioversion

  • NB: If AF Px presenting acutely with non-life threatening haemodynamic instability:


    • Rate control or rhythm control - depends time of onset of AF

NICE thromboprophylaxis treatment for new/all AF incl. paroxysmal AF: anticoagulants

  • Assess stroke risk → CHA2DS2VASc score 2 or above → anticoagulation therapy



    • C - Congestive HF/LV dysfunction (HTN with ↓ ejection fraction = 1
    • H - HTN (resting BP >140/90mmHg) or current HTN meds = 1
    • A - Age >= 75yo = 2
    • D - DM (fasting plasma glucose >=7.0 mmol/L) or insulin/DM meds = 1
    • S - Stroke/TIA/thromboembolism = 2
    • V - Vascular disease (prior MI, peripheral artery disease, aortic plaque) = 1
    • A - Age 65-75 yo = 1
    • S - Sex category - female = 1


  • ↓risk of stroke are females ( with score 1) and males (score 0) on CHADSVAS score - don't offer anticoagulation to these ↓risk Px
  • Warfarin (vitamin K-antagonist) or NOACs
    • NOACs: non-reversible effect, ££, but less monitoring ends in "-XABAN" or "-TRAN")
    • Warfarin: regular blood tests to monitor coagulation control but reversible + cheaper
  • ANTI-PLATELET therapy instead for stroke prevention if anticoagulation❌→ give aspirin + clopidogrel
    • ❌ don't prescribe aspirin or clopidogrel monotherapy/alone


  • Assess bleeding risk → HAS-BLED - to ID Px ↑risk of bleeding who can benefit from ↑vigilance to ↓risk of bleeding by managing modifiable risk factors for bleeding



    • H - HTN = 1
    • A - Abnormal liver function, renal function; alcohol (harmful consumption) = 1
    • S - Stroke = 1
    • B - Bleeding Hx of predisposition = 1
    • L - Labile INR (international normalised ratios) = 1
    • E - Elderly (>65yo) = 1
    • D - Drugs (anti-platelets or NSAIDs) = 1