Targeting LV lead for CRT with speckle-tracking echocardiography

Identifying the ideal site for left ventricular (LV) lead placement for cardiac resynchronization therapy (CRT) is a challenge to the operator. Khan FZ and colleagues [Targeted Left Ventricular Lead Placement to Guide Cardiac Resynchronization Therapy. The TARGET Study: A Randomized, Controlled Trial. J Am Coll Cardiol, doi:10.1016/j.jacc.2011.12.030] have used speckle-tracking echocardiography to identify ideal sites for LV lead implantation. The study had two hundred and twenty patients who were randomized into two groups after baseline echocardiographic speckle-tracking 2-dimensional radial strain imaging. In the study group, the LV lead was positioned at the site which had the most delayed peak contraction with an amplitude more than ten percent (to avoid scarred region). The control group had usual LV lead placement without any guidance. Patients were classified as concordant if the LV lead was at the optimal site, adjacent if the lead was within one segment and remote if it was two or more segments away. Fifteen percent or more reduction of left ventricular end systolic volume at half year was taken as the primary end point of the study. Improvement of NYHA (New York Heart Association) functional class of one or more classes, all cause mortality and composite of all cause mortality and heart failure related hospitalization were secondary end points. The responders were seventy percent in the targeted group while it was only fifty five percent in the routine group, at six months (p=0.031). Though the study results appear promising, the responder rate in the control group seems to be a bit low. The study group also had a significantly better clinical response and lower rates of combined end point of death and heart failure hospitalizations.