BOSTON—Left ventricular (LV) lead placement at or next to the site of the latest mechanical activation shows a survival benefit over remote placement, and echocardiograph-guided targeting of the site with speckle tracking is superior to routine LV lead positioning during cardiac resynchronization therapy (CRT), according to trial results presented May 11 at the 33rd annual scientific sessions of the Heart Rhythm Society.
Samir Saba, MD, of the University of Pittsburgh, who presented the data, noted that response to CRT is variable, but the researchers speculated that echo-guided lead placement could reduce this variability and improve outcomes.
To test this hypothesis, the researchers conducted a prospective study of 187 CRT patients from June 2005 to March 2011. A total of 110 patients were randomized to echo-guided LV lead placement at the site of the latest mechanical activation and 77 were randomized to a routine placement control group where echo information was not given to the physician.
Saba explained that in order to register the echo images to the fluoroscopic images, the researchers used the landmarks of the great cardiac vein in the anterior septum and the middle cardiac vein in the posterior septum, and then rotated the echo image to match orientation.
Concordance or adjacent LV lead position with the site of latest mechanical activation was achieved in 75 percent of the echo-guided group, and occurred by chance in 57 percent of controls.
Results showed the echo-guided strategy had an 11 percent relative improvement in six-month event-free survival by analyzing successful implants as well as by intention to treat. Patients with concordant or adjacent LV leads had a more favorable event-free survival at two years compared with patients with remote LV leads.
Ejection fractions were improved to 50 percent in the echo-guided group versus 26 percent in the control group.
“A strategy of echo-guided LV lead delivery at or adjacent to the site of latest mechanical activation is superior to unguided LV lead placement and may improve CRT outcomes,” summed Saba.
It also appeared to the researchers that precise location of lead placement did not affect outcomes as long as it was at least adjacent to the site of the latest activation. “The general analysis would suggest that adjacent or exact would be equally good,” said Saba. “We don’t have to be precisely at the spot and there is potentially a large ‘sweet spot,’ which people have talked about in the past.”
Saba noted that in ischemic patients, scarring may make precise placement more important than in non-ischemic patients, where the “sweet spot” may be larger.