Besides major progress in the pharmacologic treatment of severe chronic heart failure, cardiac resynchronization therapy (CRT) has developped over the last ten years. We report the follow-up of the 36 first patients with a CRT device implanted from July 2000 to November 2002 at the CHR de la Citadelle Hospital in Liege. After a mean follow up of 6 months, no death was observed. The functional benefit of resynchronization is validated by a significant improvement in the NYHA class, an increase in the walking distance measured by the six minute walk test from 268 +/- 103 to 342 +/- 106 meters (p < 0.004) and by a not significant rise in the VO2 max (from 11.1 +/- 2.8 to 14 +/- 10 ml/kg/min; P=0.1). The quality of life, assessed by the Minnesota-Living-In-CHF score, improves from 49 +/- 20 to 35 +/- 22 after the six month follow-up (P=0.02) The echocardiogram also shows a better left ventricular ejection fraction at six months, from 24 +/- 7% to 31 +/- 7% (P<0.05). Based on a better NYHA functional class, responders (n=24; 71%) and non responders (n=10; 29%) were compared; a correlation between the functional class change and the improvement of the ejection fraction was documented, but not with the reduction in QRS width. Our registry, with the potential pitfalls of a monocentric prospective study, confirms the feasability, safety and efficacy of CRT in severe chrbnic heart failure uncompletely corrected pharmocalogically. It remains however approximately 30% of non responding patients, in whom the current clinical studies should help identify the right criteria to predict and discriminate responders.