User's Manual

US-ENGLISH – 25
The optimization protocol in the clinical study specified that each
patient randomized should undergo echo guided V-V optimization. Per
the investigational plan for the MSP Clinical Trial, a uniform protocol
was used for V-V programming. This protocol required all patients to
undergo echo-guided V-V delay optimization before randomization (2 to
14 days post-implant). The optimal V-V delay was determined by
finding the programmable V-V delay and ventricular chamber pacing
order (RV then LV, or LV then RV) providing the maximum time velocity
integral (TVI or VTI) across the left ventricular outflow tract (LVOT).
Only those patients randomized to the Test arm were required to be
programmed per the optimization protocol for the V-V delay.
Of the 177 patients that presented at randomization, 3 had Model 617
which does not have V-V programmability hence the inability to
optimize. Of the remaining 174 patients, 154 (89%) were tested per the
V-V optimization protocol. One hundred forty-nine (149) of the 154
patients who were tested per the V-V optimization protocol were
programmed per the recommended or randomized V-V delay (97%).
Thirty-one (31) patients were programmed to BiV synchronous (V-V
delay 0ms), 46 were programmed to Sequential BiV (LV then RV), 22
were programmed to Sequential (RV then LV), and the remaining 50
patients were randomized to RV only.
A sub-analysis of the composite endpoint comparing the subset of
CRT-D patients with optimized V-V delays vs. the subset of patients
that did not undergo V-V delay optimization demonstrated similar
results in both groups. The CRT-D patients who did not undergo V-V
delay optimization showed a smaller improvement in the composite
endpoint, although the sample size did not permit conclusions based
on data from this subset.