Proarrhythmia is a new or more frequent occurrence of pre-existing

arrhythmia Arrhythmias, also known as cardiac arrhythmias, are irregularities in the cardiac cycle, heartbeat, including when it is too fast or too slow. Essentially, this is anything but normal sinus rhythm. A resting heart rate that is too fast – ab ...

s, paradoxically precipitated by antiarrhythmic therapy, which means it is a

side effect In medicine, a side effect is an effect of the use of a medicinal drug or other treatment, usually adverse but sometimes beneficial, that is unintended. Herbal and traditional medicines also have side effects. A drug or procedure usually use ...

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 class of drugs that are used to suppress abnormally fast rhythms (tachycardias), such as atrial fibrillation, supraventricular tachycardia and ventricular tachycardia. M ...

(VW) of

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

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

Atrial Fibrillation Atrial fibrillation (AF, AFib or A-fib) is an Heart arrhythmia, abnormal heart rhythm (arrhythmia) characterized by fibrillation, rapid and irregular beating of the Atrium (heart), atrial chambers of the heart. It often begins as short periods ...

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 (SVT). ...

Ventricular proarrhythmia

Torsades de pointes ''Torsades de pointes, torsade de pointes'' or ''torsades des pointes'' (TdP; also called ''torsades'') (, , translated as "twisting of peaks") is a specific type of abnormal heart rhythm that can lead to sudden cardiac death. It is a polymorph ...

(VW type IA and type III drugs) * Sustained

monomorphic ventricular tachycardia Ventricular tachycardia (V-tach or VT) is a cardiovascular disorder in which fast heart rate occurs in the ventricles of the heart. Although a few seconds of VT may not result in permanent problems, longer periods are dangerous; and multiple ...

(usually VW type IC drugs) * Sustained

polymorphic ventricular tachycardia Ventricular tachycardia (V-tach or VT) is a cardiovascular disorder in which fast heart rate occurs in the ventricles of the heart. Although a few seconds of VT may not result in permanent problems, longer periods are dangerous; and multiple ...

ventricular fibrillation Ventricular fibrillation (V-fib or VF) is an abnormal heart rhythm in which the Ventricle (heart), ventricles of the heart Fibrillation, quiver. It is due to disorganized electrical conduction system of the heart, electrical activity. Ventricula ...

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, sinus node or Keith–Flack 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 sin ...

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 Digoxin (better known as digitalis), sold under the brand name Lanoxin among others, is a medication used to treat various heart disease, heart conditions. Most frequently it is used for atrial fibrillation, atrial flutter, and heart failure. ...

, 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 use ...

, or

diltiazem Diltiazem, sold under the brand name Cardizem among others, is a nondihydropyridine calcium channel blocker medication used to treat high blood pressure, angina, and certain heart arrhythmias. It may also be used in hyperthyroidism if beta b ...

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

Increased risk

* Presence of structural

heart disease Cardiovascular disease (CVD) is any disease involving the heart or blood vessels. CVDs constitute a class of diseases that includes: coronary artery diseases (e.g. angina pectoris, angina, myocardial infarction, heart attack), heart failure, ...

, 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 Bradycardia, also called bradyarrhythmia, is a resting heart rate under 60 beats per minute (BPM). While bradycardia can result from various pathological processes, it is commonly a physiological response to cardiovascular conditioning or due ...

, 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