EDMONTON, Alberta -- October 30, 2009 -- Targeted placement of the left-ventricular (LV) lead in cardiac resynchronisation therapy (CRT) improves outcome, including survival, in patients with ischaemic cardiomyopathy, according to results of a study presented at the 2009 Canadian Cardiovascular Congress (CCC).
The new study demonstrated that targeting can be performed reproducibly, but found no advantage for this approach in nonischaemic cardiomyopathy.
"The closer one can get the lead to the target site, the better the mechanical remodelling," reported Derek Exner, MD, MPH, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, speaking here on October 28.
Overall, the results of this trial underscore the mechanism of action of CRT. The advantages of targeting appeared to be substantial, despite the fact that only 96 patients were randomised in the Investigating Nonresponse to Cardiac Resynchronization Therapy (INCREMENTAL) study. Moreover, promising new methodologies to improve placement may further extend the advantage. Dr. Exner reported that these results "allow us to move to a more definitive trial."
In the INCREMENTAL study, cardiomyopathy patients scheduled for CRT were randomly assigned to target LV lead placement (n = 49) or to usual placement (n = 47). They were stratified by ischaemic or nonischaemic etiology. The targeted site was defined as the latest segment to show activity on echocardiography, and these sites were confirmed to be viable with both echocardiography and magnetic resonance imaging. Response to CRT was defined as 10% or greater reduction in LV end systolic volume.
Implantation success was greater than 95% in both groups, although targeted implantation took an average of 17 minutes longer. The LV placement was near or at the target site in 80% of those in the targeted group versus 44% of those in the usual group (P < .001).
Although there was no significant advantage of targeted LV lead placement in the 40 nonischaemic patients, response was significantly higher (P = .02) and mortality was significantly lower (P = .04) in the targeted group.
This study shows that LV lead targeting is feasible. This is the first randomised evidence that targeting may improve outcomes.
The CCC is co-hosted by the Canadian Cardiovascular Society and the Heart and Stroke Foundation of Canada.
[Presentation title: Randomized Comparison of Targeted Versus Usual Left Ventricular Lead Placement in Patients Undergoing Cardiac Resynchronization Therapy. Abstract 924]
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