Mechanism:

• Focal activity, interventricular reentry, or reentry around scars (infarct, patch, etc.)

ECG characteristics:

• Premature widened QRS complex with compensatory pause (2 × RR)
  
• With retrograde atrial excitation, no compensatory pause

Etiology:

• People with no cardiac disease: idiopathic
  
• Possible in all types of cardiac disease

Treatment:

• Independent of underlying disease