ICD-10 Specific code I48.2: Chronic atrial fibrillation

Digoxin increases contractility of the myocardium by direct activity. The primary action of digoxin is specifically to inhibit adenosine triphosphatase, and thus sodium-potassium (Na+ - K+) exchange activity, the altered ionic distribution across the membrane resulting in an augmented calcium ion influx and thus an increase in the availability of calcium at the time of excitation-contraction coupling. The potency of digoxin may therefore appear considerably enhanced when the extracellular potassium concentration is low, with hyperkalaemia having the opposite effect.

Flecainide acetate is a Class IC antiarrhythmic agent used for the treatment of severe symptomatic life-threatening ventricular arrhythmias and supraventricular arrhythmias. Electrophysiologically, flecainide is a local anaesthetic-type (Class IC) of antiarrhythmic compound. It is an amide type of local anaesthetic, being structurally related to procainamide and encainide in so far as these agents are also benzamide derivatives.

Metildigoxin, a methyl derivative of digoxin, is a cardiac glycoside a type of drug that can be used in the treatment of congestive heart failure and cardiac arrhythmia.

Propranolol is a competitive antagonist at both beta, and beta₂-adrenoceptor, but has membrane stabilising activity at concentrations exceeding 1-3mg/litre, though such concentrations are rarely achieved during oral therapy. Competitive beta-blockade has been demonstrated in man by a parallel shift to the right in the dose-heart rate response curve to beta-agonists such as isoprenaline.

Verapamil inhibits the transmembrane influx of calcium ions into the heart and vascular smooth muscle cell. The myocardial oxygen demand is lowered directly as a result of the effect on the energy consuming metabolic processes of the myocardial cell and indirectly due to a reduction of the afterload. Due to its effect on coronary vascular smooth muscle, verapamil enhances myocardial blood flow, even in post‐stenotic areas, and relieves coronary spasms. These properties contribute to the anti‐ischaemic and antianginal efficacy of verapamil in all types of coronary artery disease.

Vernakalant is an antiarrhythmic medicine that acts preferentially in the atria to prolong atrial refractoriness and to rate-dependently slow impulse conduction.