Direct left ventricular endocardial pacing: an alternative when traditional resynchronization via coronary sinus is not feasible or effective.

Background: Biventricular pacing through the coronary sinus (CS) is effective for the treatment of patients with heart failure and left bundle-branch block. However, this approach is not always feasible. Although surgical epicardial lead implantation is an alternative, the technique may be deleterious in some patients.