Mechanism:

• Increased automaticity of a left atrial focus
  
• Predisposition for the origin:
  
  
  
  • In the region of the opening of the coronary sinus
    
  • In the region of the opening of the pulmonary veins
    
  • Crista terminalis
    
  • Operative scarring

Etiology:

• Hypertensive/coronary heart disease, heart defects, carditis

Treatment:

• Transseptal catheter ablation possible (success rate ca. 70%; rate of recurrence ca. 30%)
  
• Antiarrhythmics (class Ic or III)
  
• Rate control (beta-blockers, digitalis, verapamil)

ECG characteristics:

• Arrhythmia commences with increasing shortening of the cycle length (increase in frequency, so-called warming up)
  
• Arrhythmia end: increasing lengthening of the cycle length (decrease in the frequency, so-called cooling down), see above
  
• Mostly shortened PQ interval