Cardiac resynchronization therapy (CRT) by biventricular pacing is recommended, in addition to optimal medical therapy, in selected patients with congestive heart failure (CHF), advanced left ventricular (LV) systolic dys and prolonged QRS interval. Objective of biventricular pacing is to restore atrio-ventricular (A-V), inter-ventricular (V-V) and intra-LV synchrony in order to improve cardiac function and to reduce symptoms. The presence of a typical left bundle branch block (LBBB) morphology of the QRS complex is a strong pre function dictor of response to CRT with biventricular pacing, whereas right bundle branch block (RBBB) morphology and non-specific intra-ventricular conduction disturbances are associated with a low rate of response.1, This holds true especially in patients with isolated RBBB (in absence of left anterior or posterior hemiblock).2 In this condition left bundle branch is preserved and, probably, LV pacing is unnecessary, if not self-defeating. We reported a case of normalization of QRS duration after synchronized RV septal pacing in a patient with refractory CHF and RBBB. A significant narrowing of QRS complex (from 180 ms to 100 ms) was reached with a dual chamber device (Fig. 1). Final septal position of the RV lead (Fig. 2) was chosen after having observed a narrowing of the QRS complex, as compared to other septal and apical positions. Good sensed signals and pacing thresholds < 1 V @ 0.4 ms were obtained. The ICD was programmed to the DDD mode with lower rate of 60 beats/min and paced/sensed atrio-ventricular (AV) delay of 100 ms. In this case a septal positioning of right ventricular lead joined to an opportune AV setting (Fig. 3) turned a dual chamber implantable cardioverter defibrillator into a “de facto” CRT device. This occurs thanks to an optimal fusion between right ventricular septal stimulation and preserved left bundle branch conduction, leading to a significant narrowing of QRS complex. Two months later, the six minutes walking test showed that the distance walked was significantly longer than before implantation (310 m versus 240 m) and a subjective improvement of exercise tolerance from 3rd to 2nd grade in Borg scale was obtained as well. This case reported, for the first time, a clinical improvement related to this pacing technique. In our case, restored inter-ventricular (V-V) synchrony could be the reason of this significant clinical improvement. The possibility to obtain, just with a dual chamber device, a resynchronization therapy could represent a valid opportunity, instead of conventional biventricular pacing, in selected patients with heart failure and isolated RBBB. Although this technique appears simple and easily feasible, some limitations should be pointed out. An AV conduction highly variable during the day, or as occurring during exercise, could impair a correct QRS fusion. Recently, an interesting algorithm was promoted by Medtronic, AdaptivCRT , in order to promote intrinsic RV conduction in patients with LBBB, who received a biventricular device. The AdaptivCRT algorithm provides LV pacing synchronized to produce fusion with the intrinsic activation by right bundle branch when the intrinsic A-V intervals are normal. Furthermore, AdaptivCRT algorithm continuously and dynamically adapts CRT pacing method (biventricular pacing or LV pacing alone) and AV/VV delays. In patients with RBBB a similar algorithm could be proposed to obtain RV pacing synchronized to the intrinsic activation by left bundle branch. This could improve and assure an optimal QRS fusion. In this perspective, probably, biventricular devices will still play a key role in patients with CHF and RBBB.