• Cardiology Clinical Trials
• Interventional Techniques & Devices

Results from the Targeted Left Ventricular Lead Placement to Guide Cardiac Resynchronization Therapy Study (TARGET; ISRCTN19717943), presented by Fakhar Z. Khan, MD, Addenbrooke's Hospital, Cambridge, UK, show that targeted left ventricular (LV) lead placement not only is feasible but results in enhanced cardiac resynchronization therapy (CRT) response. Concordant LV lead placement, baseline dyssynchrony, and pacing away from areas of the scar are strongly related to improved CRT outcomes.

CRT has become part of the standard treatment for patients with advanced heart failure (HF) symptoms, impaired LV systolic function, and intraventricular conduction delay. Lead placement has emerged as a determinant of response. The objective of the TARGET Study was to prospectively assess the feasibility of a targeted approach to LV lead placement and the impact of LV lead targeting on CRT outcomes. The hypothesis was that targeting LV lead placement to the latest site of contraction using speckle tracking echocardiography would enhance CRT response when compared with standard unguided treatment.

TARGET was a single-blind, prospective, randomized, controlled trial in patients with New York Heart Association (NYHA) Class III–IV, left ventricular ejection fraction <35%, and QRS width >120 ms, despite maximally tolerated doses of standard HF treatment (eg, diuretics, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, beta-blockers, and aldosterone antagonists).

Subjects were randomly assigned to receive targeted LV lead placement using speckle tracking echocardiography [Goffinet C & Vanoverschelde J-L. Eur Cardiology 2007] to identify the optimal site for LV lead placement (n=110; Target Group) or standard (unguided) lead placement (n=110; Control Group). All underwent the echo procedure to identify an optimal pacing site, but in the control group, the leads were positioned with blinding to the echo data. Each placement was categorized as to whether the LV lead was positioned at the optimal site.

All CRT devices were optimized using echo following implantation. The primary endpoint was a >15% reduction in left ventricular end systolic volume (LVESV) at 6 months. Secondary endpoints were a ≥1-step improvement in NYHA Class, all-cause mortality, and a combination of mortality and HF hospitalization.

Data for 207 subjects (103 subjects in the Target Group and 104 controls) were available for analysis. Subjects had a mean age of 70 years, approximately 86% were men, and about 94% of subjects were NYHA Class III/IV. More than half (56%) of subjects had underlying cardiomyopathy.

Reduction in LVESV at 6 months (the primary endpoint) was significantly higher in subjects who received targeted lead placement compared with those who received standard lead placement (70% vs 55%; p=0.031). The group who used echo guidance had had the lead placed in an optimal position significantly more often than those who did not have echo guidance (p=0.011). Subjects in the Target Group also showed significant improvements in NYHF Class (p=0.002), the 6-minute walk test (p=0.01), and improved scores on the Minnesota Living with Heart Failure questionnaire (p=0.02). There was a significant (p=0.03) difference in the combined secondary endpoint of death and HF hospitalization, favoring the Target Group. All-cause mortality did not differ.

Targeted LV lead placement using speckle tracking 2D is feasible and associated with greater LV reverse remodeling, clinical response, and freedom from death and HF-related hospitalization. Concordant LV lead placement, baseline dyssynchrony, and pacing away from areas of the scar are strongly related to improved CRT outcomes. The speckle tracking echo technique is available for clinical use, making these results applicable to a wide range of clinical centers.

• © 2011 MD Conference Express