User Manual

18. SUPPLEMENTAL INFORMATION
refractory period, and disagreement in the statistics for swuitches to DDD. No patient
symptoms were associated with these events.
18.2. SAFER (AAI <> DDD) CLINICAL STUDY
SafeR (AAI <> DDD) mode in INTENSIA is similar to that in Symphony.
The differences in SafeR (AAI <> DDD) mode between the two devices are:
─ To prevent long RR intervals during VT/VF, SafeR (AAI <> DDD) has no effect during
VT/VF therapy, electrophysiologic studies, and post-shock recovery.
─ The maximum acceptable AV delay for first degree AV block varies as a function of
pacing rate.
─ INTENSIA requires a ventricular sensed event to atrial paced event (RA) interval of at
least 100 ms. Therefore, the device lengthens the atrial escape interval so that it ends at
least 102 ms after the ventricular event.
─ During atrial fibrillation episode, pause criterion is fixed to 2s to avoid long bradycardia
episodes in switching to DDD mode.
Despite these differences, the data collected on Symphony devices are applicable to
INTENSIA because the principles of SafeR (AAI <> DDD) operation did not change. The
criteria for switching from AAI to DDD (or vice versa) did not change. The device’s method
for evaluating the presence of AV conduction did not change.
Methods:
All patients were implanted with a Symphony Model 2550 dual-chamber rate-responsive
pacemaker with SafeR (AAI <> DDD) mode. A variety of marketed atrial and ventricular
pacing leads were used. The pacemaker was programmed and interrogated via bi-
directional telemetry using a Sorin dedicated programmer and a CPR3 programming head.
The study’s routine evaluation consisted of enrollment, pre-discharge evaluation, and a
scheduled follow-up visit at one month. At pre-discharge, a 24-hour Holter recording was
performed and pacemaker memory was read. At one month, pacemaker memory was read.
Investigators also documented adverse events.
Patients studied:
A total of 45 patients from 12 centers had Symphony 2550 pacemakers with SafeR (AAI <>
DDD). Of these, 14 (31 %) were female and 31 (69 %) were male. Mean patient age (± SD)
was 74 ± 9 years.
Primary indications for implant were: 1st degree AV block (11.1 %), 2nd degree AV block (6.7
%), 3rd degree AV block (22.2 %), sinus node dysfunction (62.2 %) or other (6.7 %).
Effectiveness results:
To determine the effectiveness of SafeR (AAI <> DDD) mode, the percentage of ventricular
pacing provided over one month was recorded from pacemaker memory.
Thirty-five patients contributed data to evaluate the percentage of ventricular pacing
provided with SafeR (AAI <> DDD). Twenty-nine patients had 1 % or less ventricular pacing
and six patients had a range of 28-97 % ventricular pacing. The graph below shows the
distribution of ventricular pacing observed in patients with and without AV block as a primary
indication for implant.
SORIN – INTENSIA CRT-D 174 – U151A
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