In this article the cases of two female patients with heart failure (functional class III) and an intrinsic complete left bundle branch block are reported. Both patients have had an implanted cardioverter defibrillator (ICD) connected to a VDD lead for primary prevention of sudden cardiac death. Atrial sensing was good/acceptable with a physiological frequency histogram and normal PQ time. A system upgrade to cardiac resynchronization therapy device (CRT) was planned. The VDD lead was directly connected to the Bivent ICD. The follow up showed stable measurements and a high biventricular pacing rate. Thus, usage of VDD leads for atrial sensing in CRT seems to be possible in a selected patient population.