New indications of cardiac pacing

New indications have recently appeared for cardiac pacing with haemodynamic and antiarrhythmic objectives without any symptomatic bradycardia. The best documented indication, though relatively rare, is stimulation of obstructive hypertrophic cardiomyopathy; initially reserved for cases with favorable results of an acute haemodynamic test, it is now used in other cases without this criterion; hypertrophic cardiomyopathy without permanent obstruction, atrial fibrillation or left bundle branch block. The improvement observed during follow-up is always greater as a real remodeling of the myocardium seems to occur with ventricular dilatation and/or septal thinning. However, the position of the atrial, and above all, of the ventricular pacing catheters is critical as is regulation of the pacemaker which should allow complete ventricular capture with an AV delay allowing good filling. The follow-up of these patients must therefore be regular and the effects on longevity are unknown. DDD pacing has also been proposed in dilated cardiomyopathy. The results are contradictory and only very selected cases with left bundle branch block and long PR interval seem justified with, again, optimisation of the pacing sites with high septal or biventricular stimulation. Recurrent atrial tachycardia, special algorithms preventing extrasystoles have been tried with variable results. In cases with interatrial block, atrial resynchronisation by bi-atrial stimulation has been assessed with promising results but many technical problems remain unsolved.