text: why lignocaine is more effective in arryhthmia due to ischaemia?   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.