Kv1.5

Post-operative atrial fibrillation is a common problem post cardiac surgery with rates exceeding 30%. Atrial fibrillation has multiple adverse effects on cardiac hemodynamics and can lead to hypotension, diminished end organ perfusion and lengthen the stay in ICU. Amiodarone is the medication of choice used for pharmacological cardioversion and can be used with vasoactive medications. Intravenous amiodarone is associated with hypotension and end organ perfusion requiring escalation in vasoactive support. Vernakalant is novel anti-arrhythmic agent approved in Canada for cardioversion of atrial fibrillation that primarily works on atrial channels and has no effect on contractility or vasodilation. Clinical trials have proved good efficacy of Vernakalant in conversion of paroxysmal atrial fibrillation however there is no comparison of Amiodarone to Vernakalant in post-operative cardiac surgery. We plan to perform a clinical trial comparing Vernakalant to amiodarone in post-cardiac surgery patients with a primary outcome of cardioversion at 90 minutes. Secondary outcomes will follow duration of vasoactive medications, days in ICU and economics.

The objective is to compare IV vernakalant to IV procainamide for the ED management of acute AF patients. If vernakalant proves to be more effective, faster, and safer than IV procainamide, this will give clinicians an important alternative for pharmacological cardioversion of acute AF. The investigators propose a pragmatic comparative effectiveness trial entailing an open label, randomized controlled trial at 12 large Canadian EDs. Study subjects will be randomized to 1 of 2 treatment arms: 1) Patients will receive an initial infusion of 3mg/kg of IV vernakalant over 10 minutes, followed by a second dose of 2mg/kg over 10 minutes, if necessary, or 2) Patients will receive a continuous infusion of 15mg/kg of IV procainamide over 60 minutes. The primary aim will be to compare conversion to normal sinus rhythm between the two drugs. The investigators will include stable patients presenting with an episode of acute AF of at least 3 hours duration, where symptoms require urgent management and where immediate cardioversion is a reasonable option. Using the integrated consent model, research assistants will obtain verbal consent from eligible patients.

The main objective of this project is to study the efficacy and the mechanistic value of blocking both atrial specific and atria-preferential dynamics of ionic currents to terminate paroxysmal atrial fibrillation (AF).
The hypothesis is that a drug blocking atrial specific and atria-preferential dynamics of ionic currents (IK,ACh - acetylcholine sensitive K+ current - and INa - inward sodium current - , respectively) will be more effective to terminate paroxysmal AF episodes with fast atrial activation rates, than a classical INa blocker, which will be more effective to terminate AF episodes with slower activation rates.
The investigators will include patients without structural heart disease and short-lasting AF episodes (<48 h.). Double blind and single center study, in which patients will be randomly assigned to a cardioversion group using intravenous flecainide or to an atria-preferential and atrial-specific blockade group using intravenous vernakalant. Patients will be routinely monitored in the electrophysiology room to acquire both 12-lead digitized ECG signals and non-invasive body surface potential mapping. Atrial signals will be extracted from both the multisite body surface and ECG recordings to obtain temporal and spectral parameters, and measure organization and atrial rate in both groups. The results obtained in the clinical setting will be studied in mathematical models to understand their capability to terminate paroxysmal AF. The project expects to provide consistent, reliable and reproducible parameters that will assist clinicians to know what type of paroxysmal AF episodes will be more suitable to effectively terminate, upon administration of drugs with an atrial specific and atria-preferential profile.