Selecting CRT candidates: the value of intracardiac mapping

Cardiac resynchronization therapy (CRT) has become standard therapy for selected patients with congestive heart failure and dyssynchrony of cardiac contraction that is a consequence of electrical dyssynchrony. Intracardiac mapping enables detailed analysis of electrical activation sequences far beyond the standard ECG and allows description of specific activation associated with the benefit of CRT. Intracardiac mapping can also localize the region of the latest ventricular activation and areas of slow conduction, and thus potentially assist in selection of optimal pacing site for CRT. Precise description of electrical activation sequences, and correlation with parameters of mechanical dyssynchrony, may contribute to understanding the principles and mechanisms underlying the effect of CRT.