Cardiac resynchronization therapy has emerged as the gold standard for heart failure patients with left ventricular systolic dysfunction and electrical dyssynchrony from an intrinsic intraventricular conduction delay or right ventricular pacing. However, the limits imposed by the coronary sinus venous anatomy restrict the applicability of the technology for many potential recipients. Furthermore, conventional resynchronization, by virtue of utilizing a single site of epicardial origin for left ventricular activation, is non-physiological. Several technologies on the horizon, including multisite pacing, left ventricular endocardial, and leadless devices, and direct His-bundle pacing are aimed at improving the response rate of cardiac resynchronization and extending candidacy to patients ineligible for conventional therapy. In this review, we discuss the limitations of the present technology and the role for these new therapies.
Keywords: Cardiac resynchronization therapy; Electrical dyssynchrony; Heart failure; Left ventricular systolic dysfunction.