Proarrhythmia
Proarrhythmia is a new or more frequent occurrence of pre-existing arrhythmias, paradoxically precipitated by antiarrhythmic therapy, which means it is a side effect associated with the administration of some existing antiarrhythmic drugs, as well as drugs for other indications. In other words, it is a tendency of antiarrhythmic drugs to facilitate emergence of new arrhythmias.
Types of proarrhythmia
According to the Vaughan Williams classification of antiarrhythmic drugs, there are 3 main types of Proarrhythmia during treatment with various antiarrhythmic drugs for Atrial Fibrillation or Atrial flutter:Ventricular proarrhythmia
- Torsades de pointes
- Sustained monomorphic ventricular tachycardia
- Sustained polymorphic ventricular tachycardia/ventricular fibrillation without long QT
Atrial proarrhythmia
- Conversion of atrial fibrillation to flutter. May be a desired effect.
- Increase of defibrillation threshold
- Provocation of recurrence. It is rare.
Abnormalities of conduction or impulse formation
- Sinus node dysfunction, atrioventricular block
- Accelerate conduction over accessory pathway
- Acceleration of ventricular rate during atrial fibrillation.
Increased risk
- Presence of structural heart disease, especially LV systolic dysfunction.
- Class IC agents.
- Increased age.
- Females.
Clinical pointers
Class IA drugs
- Dose independent, occurring at normal levels.
- Follow QT interval, keep ms.
Class IC drugs
- May be provoked by increased heart rate.
- Exercise stress tests after loading.
Class III drugs
- Dose dependent.
- Follow bradycardia, prolonged QT closely.