<unk> s are a group of pharmaceuticals that are used to suppress fast rhythms of the heart (cardiac arrhythmias), such as atrial fibrillation, atrial flutter, ventricular tachycardia, and ventricular fibrillation.
While the use of<unk> s to suppress atrial arrhythmias (atrial fibrillation and atrial flutter) is still in practice, it is unclear whether suppression of atrial arrhythmias will prolong life.
In the past, it was believed that following myocardial infarction (heart attack), suppression of ventricular arrhythmias would prolong life. However large clinical trials found that suppression of these arrhythmias would paradoxically increase mortality, which may happen due to the proarrhythmic effect these drugs may have (CAST trial).
In individuals with atrial fibrillation,<unk> s are still used to suppress arrhythmias.  This is often done to relieve the symptoms that may be associated with the loss of the atrial component to ventricular filling (atrial kick) that is due to atrial fibrillation or flutter.
The cardiac action potential
Class Ia<unk>  decreasing Vmax, thereby increasing action potential duration.
Effect of class Ib<unk> s on the cardiac action potential.
The cardiac action potential
Class Ia<unk>  decreasing Vmax, thereby increasing action potential duration.
Effect of class Ib<unk> s on the cardiac action potential.
Effect of class Ic<unk>  on cardiac action potential.
Effect of class III<unk>  on cardiac action potential.
Effect of class Ic<unk>  on cardiac action potential.
Effect of class III<unk>  on cardiac action potential.
In individuals with ventricular arrhythmias,<unk> s are often still in use to suppress arrhythmias.  In this case, the patient may have frequent arrhythmic events or be at high risk for ventricular arrhythmias.<unk> s may be considered the first-line therapy in the prevention of sudden death in certain forms of structural heart disease, and failure of these<unk> s to suppress arrhythmias may lead to implantation of an implantable cardioverter-defibrillator (ICD).
The use of<unk> s in this population may be in conjunction with an ICD.  In this case, the ICD is used to prevent sudden death due to ventricular fibrillation, while the<unk> (s) are used to suppress ventricular tachyarrhythmias so that the ICD doesn't shock the patient frequently.
Many attempts have been made to classify<unk> s.  The problem arises from the fact that many of the<unk> s have multiple modes of action, making any classification imprecise.
Antiarrhythmic agent
Anti-diabetic drug
Anti-stuttering devices
Antihypertensive
Antiplatelet drug
Thrombolytic drug
Anti-obesity medication
Decongestant