Pharmacologic Conversion of Atrial Fibrillation and Atrial Flutter

Current Drug Treatment Strategies for Atrial Fibrillation and TASK-1 Inhibition as an Emerging Novel Therapy Option

Atrial fibrillation (AF) is the most common sustained arrhythmia with a prevalence of up to 4% and an upwards trend due to demographic changes. It is associated with an increase in mortality and stroke incidences. While stroke risk can be significantly reduced through anticoagulant therapy, adequate treatment of other AF related symptoms remains an unmet medical need in many cases. Two main treatment strategies are available: rate control that modulates ventricular heart rate and prevents tachymyopathy as well as rhythm control that aims to restore and sustain sinus rhythm. Rate control can be achieved through drugs or ablation of the atrioventricular node, rendering the patient pacemaker-dependent. For rhythm control electrical cardioversion and pharmacological cardioversion can be used. While electrical cardioversion requires fasting and sedation of the patient, antiarrhythmic drugs have other limitations. Most antiarrhythmic drugs carry a risk for pro-arrhythmic effects and are contraindicated in patients with structural heart diseases. Furthermore, catheter ablation of pulmonary veins can be performed with its risk of intraprocedural complications and varying success. In recent years TASK-1 has been introduced as a new target for AF therapy. Upregulation of TASK-1 in AF patients contributes to prolongation of the action potential duration. In a porcine model of AF, TASK-1 inhibition by gene therapy or pharmacological compounds induced cardioversion to sinus rhythm. The DOxapram Conversion TO Sinus rhythm (DOCTOS)-Trial will reveal whether doxapram, a potent TASK-1 inhibitor, can be used for acute cardioversion of persistent and paroxysmal AF in patients, potentially leading to a new treatment option for AF.

"Pill in the Pocket" Antiarrhythmic Drugs for Orally Administered Pharmacologic Cardioversion of Atrial Fibrillation

The therapy of atrial fibrillation often involves the use of a rhythm control strategy, in which 1 or more antiarrhythmic drugs (AAD), ablative procedures, and/or hybrid approaches involving both of these options are utilized in an attempt to restore and maintain sinus rhythm. For chronic therapy, an AAD is taken daily. However, for patients with symptomatic but infrequent, acute, but nondestabilizing episodes, the use of an AAD only at the time of an episode that can quickly restore sinus rhythm, generally as an out-patient, without the burden of a daily drug regimen, may be better. This is called "pill-in-the-pocket" therapy. This manuscript reviews the "pill-in-the-pocket" concept, traces its development from its origins using quinidine, to its expansion using class IC AADs, to the more recent investigation of ranolazine for this purpose. Who should get it, what it involves, its efficacy rates and concerns are all discussed.