A different cardiac resynchronization therapy technique might be needed in some patients with nonspecific intraventricular conduction disturbance pattern.

BACKGROUND: Current cardiac resynchronization therapy (CRT), devised to eliminate dyssynchrony in left bundle branch block (LBBB), works by pacing the latest activated left ventricular site (LALVS). We hypothesized that patients with nonspecific intraventricular conduction disturbance (NICD) pattern respond less favorably to CRT, because their LALVS is far away from that in LBBB. METHODS: = 33). RESULTS: away from the LALVS, the LALVSs were located leftward, posterosuperior in the LBBB group, slightly left, superior in the NICD-1 subgroup, and slightly left, posteroinferior in the NICD-2 subgroup. The LALVS determined by ECG and echocardiography matched in all patients, except two. CONCLUSIONS: In the NICD-2 subgroup, a remote LALVS was found from that in LBBB pattern, which might explain the high non-response rate of the NICD pattern to the current CRT technique.