Atrial Fibrillation, Diagnosis and Initial Treatment

Terminology

• Atrial fibrillation is a supraventricular tachyarrhythmia characterized by chaotic, disorganized electrical activation and inefficient atrial contraction

Epidemiology

• Atrial fibrillation is the most common sustained cardiac arrhythmia, with a worldwide prevalence of more than 37 million (0.5% of the global population)(1)

• Incidence and prevalence have risen steadily over the past 20 years, and they are projected to continue to rise(1)

Etiology and Risk factors

Etiology

• Atrial fibrillation episodes are initiated by premature atrial complexes

  • Typically originate in the pulmonary veins (called pulmonary vein triggers)

  • May also come from the other structures (called non–pulmonary vein triggers2), including: • Right atrium • Superior vena cava • Posterior wall of left atrium • Vein of Marshall • Left atrial appendage

Risk Factors

• Risk factors for atrial fibrillation

  • Cardiac factors

  • Hypertension

  • Coronary artery disease

  • Heart failure

  • Hypertrophic cardiomyopathy

• Extracardiac factors

  • Obesity

  • Metabolic syndrome

  • Sleep apnea

  • Diabetes mellitus

  • Excessive alcohol consumption

  • Hyperthyroidism

• Genetic factors

  • Sometimes familial

    • Patterns of autosomal dominant inheritance have been described in some families3

    • Numerous genetic mutations have been linked to atrial fibrillation, including:

      • Ion channel mutations (sodium and potassium channels)

      • Non–ion channel mutations (eg, lamin, connexin, ryanodine receptor, cardiac transcription factors)3 European ancestry is a risk factor4

• Advancing age

Approach to Diagnosis

• Presence is suggested by findings on physical examination and confirmed by ECG

Staging or Classification

• Classified according to predominant duration of episodes

  • Paroxysmal (terminating spontaneously or by intervention in less than 7 days)

  • Persistent (more than 7 days, often requiring direct-current cardioversion)

  • Long-standing persistent (continuous atrial fibrillation for 1 year or longer)

  • Permanent (accepted as long-term by the patient and physician, with no plans to pursue rhythm control)