text: It acts to reduce the electrical activity of the heart, therefor inhibiting ectopic loci- It is not used a great deal anymore.Class I agents have generally fallen into disfavour, notably in patients with underlying ischaemic heart disease, notably following the CAST study where mortality increased by 6%. Encainide and Propafenone are occasionally used for maintenance of sinus rhythm in patients with supra-ventricular arrhythmias such as atrial fibrillation provided there is no underlying structural heart disease. Similar, infrequently used agents with Class I actions are mexiletine, tocainide (which also causes bone marrow aplasia / lung fibrosis), and moricizine. Lignocaine is still useful for some acute ventricular arrhythmias, but its routine use in ischaemic heart disease must be strongly condemned.