Frequent ventricular extrasystole, isolated or paired, bigeminism or trigeminism, at rest or during exercise, is a common cause of decrease in the percentage of biventricular pacing. It also causes a relative bradycardia as the PVCs are relatively ineffective from an hemodynamical point of view. In resynchronized patient, the evolution of the frequency of PVCs should be continuously monitored because they can be promoted by metabolic disorders and induced by drugs, or express the worsening underlying heart disease, or even being at the origin of clinical decompensation. In non-responder patients, suppressing the PVCs is a priority to allow an increase in the percentage of biventricular pacing and thus expect a positive response to the resynchronization therapy. Different options are possible: 1) in this patient, an increase in the minimum rate at 70 bpm has eliminated the PVCs. A rate responsive function has also been programmed to force the atrial pacing during exercise. The effect of this type of programming on the PVC is often incomplete or only temporarily effective. Moreover it is occasionally necessary to program relatively high heart rate at rest (> 80 bpm), which is difficult to accept on the long term in those patients with a severe heart failure; 2) the anti-arrhythmic drug therapy (beta-blockers, amiodarone) are rarely effective in this context; 3) In the presence of monomorphic extrasystole a radiofrequency ablation procedure can be proposed. This last option is indicated in cases of impaired hemodynamic status or left ventricular function. The evaluation of the correlation between the functional and the clinical abnormalities is essential for the decision making process.