[The best of cardiac pacing in 1999]

Since the first clinical application to man forty years ago, for the treatment of bradycardia, cardiac pacing has been the object of continuous technological innovation in parallel with those in electronics and computerisation. However, independently of these expected advances, there has been a surprising widening of the field of application of pacing into those of haemodynamics and rhythmology. The recent publication of the long-term results of the Pacing in Cardiomyopathy (PIC) study confirmed the sustained decrease of intraventricular pressure gradient, of NYHA functional stage and improved quality of life of patients with hypertrophic obstructive cardiomyopathy paced in the DDD mode. The investigators also underlined the placebo effect of the pacemaker. The decrease in risk of sudden death and the reduction in ventricular remodelling have not been demonstrated yet. More recently, biventricular pacing has been proposed for the treatment of dilated cardiomyopathy and a French study showed a long-term improvement in NYHA stage and effort capacity. Several prospective randomised trials are under way to validate this indication. Acute haemodynamic evaluations have confirmed the efficacy of biventricular stimulation but also underline the value of left ventricular pacing alone. The effects on mortality, the selection of patients and the optimal configuration of pacing remain to be defined. In the field of prevention of atrial arrhythmias, the results of the multicenter SYNBIAPACE study, investigating biatrial pacing in patients with interatrial conduction defects, only showed a tendency to an increase in the delay before recurrence of atrial fibrillation. The value of the memory functions of pacemakers and the algorithms of prevention of atrial arrhythmias are still under investigation. Haemodynamic transducers have been introduced in some recent pacemakers to assess myocardial contractility and have applications in the evaluation of different pacing modes and in the optimisation of the atrioventricular interval. Their value in the treatment of neurocardiogenic syncope is under evaluation. In conclusion, it is not overoptimistic to imagine that, in the near future, the cardiac pacemaker will be part of a "control and treatment system" well over the limits of treating patients with bradycardia.