Incidence & Predictors of Mechanical Abnormalities of QuickSite® and QuickFlex® Left Ventricular Pacing Leads

On April 2, 2012 the manufacturer of the Quicksite® and Quickflex® leads, St. Jude Medical,
released a voluntary medical device advisory regarding these leads' potential for problems
with the silicone insulation covering one end of the lead, where it meets another section of
the lead which is coated with a different insulating material (polyurethane). There has been
a voluntary suspension of sales of these leads.

There are approximately 179,000 of the above leads implanted worldwide with an estimated
101,000 leads currently in service (59,000 in US). There have been 39 confirmed cases of the
conductor portion of the lead becoming exposed from the silicone insulation
(externalization), and the rate of occurrence of this type of problem is conservatively
estimated at less than one percent. However, a review done by St. Jude Medical of returned
Quicksite® and Quickflex® leads and available X-ray and fluoroscopic (x-ray movie) images of
patients with these leads (from 1,219 patients) revealed a higher rate of 3-4%. It is
presumed that there are patients whose leads have not yet been affected by this problem, but
whose leads may show signs of structural changes on x-ray or fluoroscopy. This study seeks
to determine what structural changes may be occurring in these leads, what signs might
predict these changes, and what impact these changes may have on the lead and its
performance.