Left ventricular (LV) lead position has crucial impact on cardiac resynchronization therapy (CRT) success. This study will compare fluoroscopy and myocardial deformation imaging for optimal definition of LV lead position.

In a 16 segment model circumferential strain will be used to determine the segment with latest peak systolic circumferential strain prior to CRT, considered as the optimal LV lead target. LV lead will be defined by (1) fluoroscopy, (2) the maximal temporal difference of peak circumferential strain before-to-on CRT and (3) the earliest peak systolic circumferential strain during LV pacing. For all 3 modalities optimal LV lead position is defined as concordance or immediate neighbouring of the segment with defined LV lead position to the determined optimal target segment. At follow-up echocardiography will be performed to determine improvement in LV function and remodeling.

Inclusion Criteria:

• See above
• Males and females
• Ages 18 to 80 years

Exclusion Criteria:

• Patients who already have had a pacemaker device
• Patients with poor echocardiographic window
• Patients who are not able to understand the study and to give informed written consent

Consecutive patients with end-stage heart failure and sinus rhythm, scheduled for new implantation of a biventricular pacemaker were included in the study. Criteria for CRT implantation were New York Heart Association (NYHA) functional class III (N=35) or IV (N=21) despite optimal pharmacologic therapy and evidence of LV systolic dysfunction with ejection fraction <35% and a QRS >120ms.