Do patients with heart failure and right bundle branch block need biventricular pacing? A case of significant QRS narrowing by right ventricular pacing alone.

We report the case of a 56-year-old male with ischemic cardiomyopathy, severe left ventricular dysfunction and right bundle branch block (RBBB) with a wide QRS duration (180ms) who received dual-chamber implantable cardioverter-defibrillator for primary prevention of sudden death. After having placed the right ventricular lead in the middle of the inter-ventricular septum, a significant narrowing of QRS duration was observed, thus obtaining "de facto" a cardiac resynchronization therapy (CRT). This type of cardiac pacing could be an alternative to conventional CRT with left ventricular pacing in patients with wide QRS due to RBBB. The long-term effects of this RV only pacing strategy with ICD in patients with heart failure yet remain to be determined.