AF Summary

AF Classification

  • Paroxysmal: Episodes <7 days, self-terminating
  • Persistent: Episodes >7 days, requires cardioversion
  • Permanent: Long-standing, cardioversion not indicated

Key Symptoms

  • Irregular pulse
  • Palpitations
  • Breathlessness
  • Chest discomfort
  • Dizziness/syncope

ECG Diagnosis

  • Absent P-waves
  • Chaotic baseline (fibrillatory waves)
  • Irregularly irregular ventricular rate
  • Rate typically 160-180 bpm

Acute Management

  • Unstable: Emergency cardioversion
  • Recent-onset (<48h): Pharmacological/electrical cardioversion
  • Rate control: Beta-blockers, CCBs, digoxin

Anticoagulation

  • Use CHA₂DS₂-VASc score for stroke risk
  • Consider for males with score ≥1
  • Offer for score ≥2
  • Options: DOACs or warfarin

Long-term Management

  • Rhythm control: For symptomatic patients
  • Rate control: First-line for most patients
  • Ablation: For drug-resistant paroxysmal AF

Complications

  • Stroke/thromboembolism
  • Heart failure
  • Tachycardia-induced cardiomyopathy
  • Increased mortality

Atrial Fibrillation (AF)

A supraventricular tachyarrhythmia with irregular, disorganized electrical activity and ineffective atrial contraction

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Classification

Paroxysmal AF

  • Episodes lasting >30 seconds but <7 days
  • Often <48 hours
  • Self-terminating and recurrent

Persistent AF

  • Episodes lasting >7 days
  • Requires pharmacological/electrical cardioversion
  • Unlikely to self-terminate

Permanent AF

  • Fails cardioversion or relapses within 24 hours
  • Usually >1 year duration
  • Cardioversion not indicated/attempted

Pathophysiology

Causes

Cardiac Conditions

  • Hypertension
  • Coronary artery disease
  • Myocardial infarction
  • Heart failure
  • Valvular disease (especially rheumatic)
  • Congenital heart disease
  • Cardiomyopathies
  • Pericarditis

Non-Cardiac Conditions

  • Hyperthyroidism
  • Pulmonary embolism
  • Acute infection
  • Electrolyte imbalances
  • Malignancy (lung, metastatic)
  • Diabetes mellitus

Lifestyle Factors

  • Excessive alcohol ("Holiday heart")
  • Obesity
  • Smoking
  • High caffeine intake
  • Certain medications (thyroxine, bronchodilators)

PIRATES Mnemonic for Secondary Causes

  • Pulmonary embolism
  • Ischemia
  • Respiratory disease
  • Atrial enlargement/myxoma
  • Thyroid disease
  • Ethanol
  • Sepsis/Sleep apnea

Complications

Stroke risk is similar across all AF classifications (paroxysmal, persistent, permanent)

Stroke & Thromboembolism

  • Main complication of AF
  • Anticoagulation reduces risk by ~2/3
  • Due to stasis in left atrial appendage

Heart Failure

  • Ineffective ventricular filling
  • Cardiac output reduced by 10-20%
  • Can decompensate existing HF

Other Complications

  • Tachycardia-induced cardiomyopathy
  • Critical cardiac ischemia
  • Increased mortality (correlates with CV disease severity)

Diagnosis

Suspected AF Presentation

ECG Findings

  • Absent P-waves
  • Chaotic baseline (fibrillatory waves)
  • Irregularly irregular ventricular rate
  • Rate typically 160-180 bpm (may be lower)
  • Normal QRS complexes (unless conduction defect)

Additional Testing

Paroxysmal AF

  • 24-hour Holter monitor (if episodes <24h apart)
  • Event recorder (if episodes >24h apart)
  • 7-day Holter as alternative

Underlying Causes

  • Echocardiogram (structural heart disease)
  • Thyroid function tests
  • Electrolytes (K+, Mg++)
  • CXR (lung pathology)

Differential Diagnosis

Condition Key Features
Atrial flutter Saw-tooth atrial pattern on ECG
Atrial/ventricular ectopics Irregular pulse but regular underlying rhythm
Sinus tachycardia Regular rhythm >100 bpm with P-waves
SVTs Regular narrow-complex tachycardia
Multifocal atrial tachycardia Irregular rhythm with ≥3 P-wave morphologies

Acute Management

Hemodynamically Unstable AF

  • Emergency electrical cardioversion (120-150J synchronized)
  • Indications:
    • Shock
    • Syncope/reduced consciousness
    • Acute heart failure
    • Myocardial ischemia
  • Do not delay for anticoagulation

Recent-onset AF (<48 hours)

Pharmacological Cardioversion

  • No structural/ischemic heart disease: Flecainide
  • Structural heart disease: Amiodarone

Electrical Cardioversion

  • Synchronized DC shock (120-150J)
  • Preferred if >48 hours duration

Rate Control Strategy

First-line for most AF patients unless:

  • Reversible cause
  • HF primarily caused by AF
  • New onset AF (<48h)
  • Rhythm control more suitable clinically
Medication Notes
Beta-blockers (metoprolol) First-line for most patients
Rate-limiting CCBs (diltiazem) Alternative first-line
Digoxin Only for sedentary patients with non-paroxysmal AF

Anticoagulation

For AF >48h or uncertain duration: anticoagulate for ≥3 weeks before cardioversion

CHA2DS2-VASc Score

Risk Factor Points
Congestive HF/LV dysfunction 1
Hypertension 1
Age ≥75 2
Diabetes 1
Stroke/TIA 2
Vascular disease 1
Age 65-74 1
Female sex 1

Anticoagulation guidelines:

  • Consider for males with score ≥1
  • Offer for score ≥2
  • Options: DOACs (apixaban, rivaroxaban, dabigatran) or warfarin

ORBIT Bleeding Risk Score

Risk Predictor Points
Older age (>74 years) 1
Reduced hemoglobin/Anemia (below normal range)Low Hb (M<13/F<12 g/dL) 2
Bleeding history (GI bleeding, intracranial bleeding, or hemorrhagic stroke) 2
Insufficient kidney function (GFR <60 mL/min/1.73m²) 1
Treatment with antiplatelet agents 1

Interpretation

  • Low risk: 0-2 points
  • Intermediate risk: 3 points
  • High risk: ≥4 points

Use the ORBIT score to assess bleeding risk when considering anticoagulation for AF patients.

Long-term Management

Rhythm Control

Ablation Strategies

Catheter Ablation

  • Offer for paroxysmal AF if drugs fail/unsuitable
  • Consider for persistent AF

AV Node Ablation + Pacing

  • For permanent AF with:
  • Symptoms from high ventricular rates
  • LV dysfunction from rate-related cardiomyopathy