User Manual Part 4

CLINICAL STUDY - C ONTAK CD
D-29
90
80
70
85
0
Complication-free Rate (%)
75
Acceptance Boundary
All Patients
(NYHA Class II / III / IV)
NYHA Class III / IV
Figure D-11. System safety
Verification of CRT Delivery
The delivery of biventricular pacing throughout the CONTAK CD Study was
confirmed by comparing the programmed device output to the biventricular
pacing threshold and demonstrating that c apture was maintained in daily
activities and during exercise.
The investigational plan recommended programming the device output to at
least twice the biventricular pacing voltage threshold. Electrocardiograms
(ECGs) from Holter Monitors during daily activities were received and analyzed
to verify that total capture was maintained at the 3-month and 6-month visits
and to ensure that the safety margin was adequate. Cardiopulmonary exercise
tests (CPX) were performed on patients who were randomized to receive CRT
therapy at 3- and 6- mont h visits.
• In 623 evaluations of safety margin at baseline, three-, and six-months, the
device output was programmed to deliver a voltage approximately three
times that necessary to stimulate both ventricles.
• A total of 1139 Holter monitors were placed throughout the study at
baseline, three-, and six-months. The tests indicated only 4 instances
(0.4%) of inappropriate pacing or sensing that were all corrected with
device programming.
• A total of 316 CPX tests at the three- and six-month follow-up visits were
performed in patients with CRT who also had interpretable ECG results. Of
these, 277 (88%) had continuous CRT delivery throughout exercise. The
remaining 39 patients (12%) had continuous CRT delivery until the sinus
rate exceeded the maximum tracking rate (MTR).
- DRAFT -