Hemodynamic benefits of left ventricular pacing in two pacemakers syndromes with refractory heart failure

We describe two cases in which right ventricular pacing produced severe hem odynamic deterioration and in which changing the pacing from the right to t he left ventricle sharply corrected these alterations, while simultaneous b iventricular pacing did not. Chronical left ventricular pacing can solve he modynamic alterations in severe pacemaker syndromes, thereby avoiding the n eed for mitral prothesis implantation in some cases. The use of this proced ure today should be individualized, including acute hemodynamic and echocar diographic studies, because the width of the QRS complex during pacing is n ot a significant predictor of hemodynamic efficiency.