Proarrhythmia is a new or more frequent occurrence of pre-existing arrhythmias, paradoxically precipitated by antiarrhythmic therapy, which means it is a

side effect In medicine, a side effect is an effect, whether therapeutic or adverse, that is secondary to the one intended; although the term is predominantly employed to describe adverse effects, it can also apply to beneficial, but unintended, consequence ...

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 Antiarrhythmic agents, also known as cardiac dysrhythmia medications, are a group of pharmaceuticals that are used to suppress abnormally fast rhythms ( tachycardias), such as atrial fibrillation, supraventricular tachycardia and ventricular ta ...

(VW) of

antiarrhythmic Antiarrhythmic agents, also known as cardiac dysrhythmia medications, are a group of pharmaceuticals that are used to suppress abnormally fast rhythms (Tachycardia, tachycardias), such as atrial fibrillation, supraventricular tachycardia and vent ...

drugs, there are 3 main types of Proarrhythmia during treatment with various antiarrhythmic drugs for Atrial Fibrillation or

Atrial flutter Atrial flutter (AFL) is a common abnormal heart rhythm that starts in the atrial chambers of the heart. When it first occurs, it is usually associated with a fast heart rate and is classified as a type of supraventricular tachycardia. Atrial f ...

Ventricular proarrhythmia

Torsades de pointes ''Torsades de pointes, torsade de pointes'' or ''torsades des pointes'' (TdP) (, , translated as "twisting of peaks") is a specific type of abnormal heart rhythm that can lead to sudden cardiac death. It is a polymorphic ventricular tachycardia t ...

(VW type IA and type III drugs) * Sustained

monomorphic ventricular tachycardia Ventricular tachycardia (V-tach or VT) is a fast heart rate arising from the lower chambers of the heart. Although a few seconds of VT may not result in permanent problems, longer periods are dangerous; and multiple episodes over a short perio ...

(usually VW type IC drugs) * Sustained

polymorphic ventricular tachycardia Ventricular tachycardia (V-tach or VT) is a fast heart rate arising from the lower chambers of the heart. Although a few seconds of VT may not result in permanent problems, longer periods are dangerous; and multiple episodes over a short perio ...

ventricular fibrillation Ventricular fibrillation (V-fib or VF) is an abnormal heart rhythm in which the ventricles of the heart quiver. It is due to disorganized electrical activity. Ventricular fibrillation results in cardiac arrest with loss of consciousness and n ...

without long QT (VW types IA, IC, and III drugs)

Atrial proarrhythmia

* Conversion of atrial fibrillation to flutter (usually VW type IC drugs or amiodarone). May be a desired effect. * Increase of defibrillation threshold (a potential problem with VW type IC drugs) * Provocation of recurrence (probably VW types IA, IC and III drugs). It is rare.

Abnormalities of conduction or impulse formation

Sinus node The sinoatrial node (also known as the sinuatrial node, SA node or sinus node) is an oval shaped region of special cardiac muscle in the upper back wall of the right atrium made up of cells known as pacemaker cells. The sinus node is approxima ...

dysfunction,

atrioventricular block Atrioventricular block (AV block) is a type of heart block that occurs when the electrical signal traveling from the atria, or the upper chambers of the heart, to ventricles, or the lower chambers of the heart, is impaired. Normally, the sinoatr ...

(almost all drugs) * Accelerate conduction over accessory pathway ( digoxin, intravenous

verapamil Verapamil, sold under various trade names, is a calcium channel blocker medication used for the treatment of high blood pressure, angina (chest pain from not enough blood flow to the heart), and supraventricular tachycardia. It may also be ...

, or diltiazem) * Acceleration of ventricular rate during atrial fibrillation (VW type IA and type IC drugs).

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.

References

External links

* {{cite journal , doi=10.1016/S0002-9149(98)00472-X , author=Roden DM , title=Mechanisms and management of proarrhythmia , journal=Am. J. Cardiol. , volume=82 , issue=4A , pages=49I–57I , date=August 1998 , pmid=9737654 Symptoms and signs Medical terminology Cardiac arrhythmia