Cryoballoon Ablation Procedure
Index Procedure: Procedural guidance (described here) was
provided to inform use of the novel study device, but in general
procedures were performed in accordance with local standard of care at
physician discretion.
Dosing recommendation: Cryoapplications were recommended based
on an algorithm measuring time to isolation (TTI), with a 180s
application where TTI occurred in less than 60s and a 240s application
where TTI occurred after 60s or was not detected, but the duration and
number of cryoapplications was at physician discretion.
Esophageal management: Esophageal monitoring was required with
a recommended cut-off temperature of 20°C.
Phrenic Monitoring: Phrenic nerve monitoring with the
integrated DMS (Diaphragm Movement Sensor) was recommended, in
conjunction with local standard of care monitoring. The integrated DMS
allows the physician to monitor the amplitude of paced electromyogram
like potential based movement recorded from an external sensor and
visible as real time changes in amplitude on the cryoablation system,
with an adjustable threshold and automatic recommendations to stop the
cryoablation if the electrogram amplitude decreases by a pre-set
percentage, see Supplement. In this study the DMS was recommended to be
set at 65%. Phrenic nerve impairment was confirmed with a “sniff
test” or radiography during the index procedure, discharge, and
follow-up visits until resolved.
PVI Procedure: Procedural guidance (described here) was
provided to inform use of the novel study device, but in general
procedures were performed in accordance with local standard of care at
physician discretion. Cardioversion was performed at operator
discretion. Anti-coagulation was recommended to be uninterrupted or
minimally interrupted prior to procedure. PVI procedures were conducted
based on local standard of care and cryoablation system instruction for
use. Acute success was confirmed by entrance and exit block, lack of
confirmed or recorded block was reported as acute procedural failure.
Additional ablations: Additional ablation of non-PV foci that
initiate AF (including locations in the left atria, right atrium, or
superior vena cava), targeting complex fractionated electrograms or
ganglionated plexi or performing LA mitral isthmus or roof lines was not
allowed. Additional ablation of the cavo-tricuspid isthmus (CTI) with a
market approved RF catheter was allowed in cases where typical atrial
flutter was documented by patient history or occurred during the case
(either spontaneously or inducible).
Redo Ablations: One repeat ablation was allowed during
blanking, use of ‘non-study’ device for redo was considered a failure.
Follow-Up: Follow-up was performed at discharge, 7 days, 3
months, 6 months, and 12 months post index procedure. Trans telephonic
monitoring (TTM) was collected by patients 2 times per month (either
symptomatic or asymptomatic) from 3 to 12m post procedure. Only 43
subjects had monitoring related deviations. 24h Holter monitoring was
provided at the 12m FU visit.