Sequential versus Simultaneous Biventricular Pacing and Biventricular versus Left Univentricular Pacing in Cardiac Resynchronization Therapy

Multisite ventricular pacing, including left ventricular pacing, is associated with hemodynamic, echocardiographic and clinical benefits in patients with congestive heart failure (CHF) and left ventricular dysfunction undergoing cardiac resynchronization therapy (CRT). The clinical outcome of CRT using left univentricular pacing (LVp) is essentially comparable to other CRT pacing modalities (sequential or simultaneous biventricular pacing, BiVp), although BiVp appears to be associated with a greater improvement of the left ventricular performance. Biventricular pacing, unlike LVp, is also associated with a greater reduction in the QRS complex duration, which has been described as a predictor of good outcome in CRT patients. Sequential BiVp appears to be superior to simultaneous BiVp, although the clinical impact of these two CRT pacing modalities is essentially equal in the long-term follow-up. Left univentricular pacing is limited by the increasing indication of devices allowing for antitachycardia/defibrillation therapy in CRT patients, for which a right ventricular lead is needed. However, this pacing modality might be indicated in a selected CHF population with important comorbilities, difficult venous access for the lead implantation and/or unfavorable life time expectancy.

Keywords: Sequential biventricular pacing, simultaneous biventricular pacing, left univentricular pacing, cardiac, resynchronization therapy