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Cardiac stimulation in heart failure: are we going too fast, are we going too far?

Everything started with Hochleitner in 1990 who published on the beneficial effects of dual chamber pacing with short AV delay in a small population of patients with congestive heart failure. Thereafter, several authors reported contradictory results applying the same methods in similar populations. In the early 1990s, we all learned from Rosenqvist and Leclercq, that it is possible to modify the ventricular mechanical activation sequence with pacing, right ventricular apical pacing being deleterious to haemodynamics and myocardial metabolism. Therefore, several attempts at right outflow tract pacing again showed varying results in similar patients. Although individual benefit was sometimes observed, global results were frustratingly inconclusive. Daubert et al. opened the era of multisite stimulation by performing bi-atrial pacing with the aim of preventing atrial tachyarrhythmias in very selected patients. The many reports from his centre led us to imagine that biventricular stimulation with optimization of AV synchrony, could improve patients with congestive heart failure and delayed left ventricular contraction. Our first attempt at multisite stimulation was performed in 1994, and was very encouraging with immediate, spectacular and long-lasting improvement in the patient. Since then, a feasibility study has been started in NYHA class IIIb and IV patients, specific leads were designed for coronary sinus catheterization for definitive left ventricular pacing (to avoid the surgical epicardial approach) and specific devices were developed with separated connections (to avoid the use of lead adaptors). These systems are now being used in several trials (InSync device assessment study, MUSTIC, PATH-CHF, VIGOR-CHF trials, etc . . .). The results of the longitudinal InSync trial confirmed those of the feasibility study, with a consistent longterm functional benefit of biventricular stimulation. However, the results of the controlled trials are not yet published. Enthusiasm is growing among manufacturers and doctors. All teams which started to implant cardiac stimulators (or synchronizers), found the same spectacular results, with the proviso