[Biventricular stimulation for AV block].

Since the establishment of cardiac resynchronization therapy in left bundle branch block and mechanical asynchrony, the adverse effects of right ventricular apical pacing have gained increasing scientific interest. The sequelae of "iatrogenic desynchronization" on cardiac structure and function as well as on patients' prognosis could be well documented. "Minimally desynchronizing" stimulation strategies could be an alternative for patients needing ventricular pacing. The search for hemodynamically more advantageous alternative right ventricular pacing sites has failed so far to deliver well validated results, and due to the somewhat higher lead dislodgment rates pure left ventricular pacing cannot be recommended, at least not in pacemaker-dependent patients. Hence there is the question for primary biventricular stimulation in patients with AV block. The results of several biventricular studies with limited numbers of patients have been promising with respect to structural and functional surrogate endpoints. Two major controlled prospective and prognostically orientated studies, the BIOPACE study and the BLOCK-HF study, are currently underway and will report results in the next few years. According to the actual guidelines of the European Society of Cardiology (ESC) the implantation of a biventricular system is recommended in patients with AV block even without left bundle branch block (Class IIa, evidence level C) if they fulfill the remaining criteria that justify the implantation of a biventricular system. According to the guidelines for pacemaker therapy of the German Cardiac Society (GCS) biventricular pacing can be considered in these patients. Both societies do expressly permit the implantation of biventricular systems with ICD backup if indicated.