Results
Baseline characteristics: There were 57,206 patients who had at
least one record indicating an AF ablation procedure, 2,402 (4.2%) of
which had a Medtronic CIED implanted prior to the first AF ablation
procedure on record, and 665 (1.2%) of which satisfied the full
inclusion/exclusion criteria. Of those, 417 (62.7%) patients had
persistent AF (mean age 67.3 ± 9.0, 73.6% male) and 248 (37.3%)
patients had paroxysmal AF (mean age 66.2 ± 9.3, 73.0% male) as defined
by their AF pattern within 30 days prior to ablation (Table 1). The mean
time between AF ablation procedure and last observed daily AF burden was
22.7±14.7 months.
Recurrence of Atrial Fibrillation: In patients with paroxysmal
AF (Figure 1, Panel A), survival free from AF recurrence at 1-year post
blanking period varied from 28.2% (using a definition of AF recurrence
of >6 minutes) to 72.1% (using the definition
>23 hours). Similarly, in patients with persistent AF,
survival free from AF recurrence at 1-year post blanking period ranged
from 24.9% (using a definition of AF recurrence of >6
minutes) to 60.0% (using the definition of 7 consecutive days
>23 hours; Figure 1, Panel B).
Atrial Fibrillation Burden Reduction Following Ablation: Of the
248 patients with paroxysmal AF, the, overall median percentage of time
in AF was reduced by 99.6% (from 23.7% prior to ablation to 0.1%
following ablation) and the overall median daily AF burden was reduced
from 0.28 to 0 hours (Figure 2). Of the 417 patients with persistent AF
at baseline, the overall median percentage of time in AF was reduced by
99.3% (from 67.5% prior to ablation to 0.5% following ablation) and
the overall median of median daily AF burden was reduced from 23.98 to 0
hours (Figure 3).
Monitoring Strategy Simulation: Out of the 665 patients who
satisfied the inclusion/exclusion criteria, 369 (55.5%) had at least 1
year of uninterrupted daily AF observations (thus included in the
monitoring strategy simulation), of which 137 had paroxysmal AF and 232
had persistent AF at baseline. Of the 138 patients with paroxysmal AF at
baseline, 101 (73.7%), 72 (52.6%) and 41 (29.9%) had a least one day
with AF > 6 min, AF > 6 hours and AF
> 23 hours, respectively within 1-year post blanking
period. Of the 232 patients with persistent AF at baseline, 174
(75.0%), 134 (57.8%) and 112 (48.3%) had a least one day with AF
> 6 min, AF > 6 hours and AF > 23
hours respectively within 1-year post blanking period. Sensitivity and
NPV estimates for all monitoring strategies are graphically displayed in
Figure 4 (Panel A for patients with paroxysmal AF and Panel B patients
with persistent AF). For patients with paroxysmal AF, the 30-day
monitoring strategy had the highest estimates for sensitivity (64.8%)
and NPV (50.4%), whereas for patients with persistent AF, the quarterly
7-day monitoring strategy had the highest estimates for sensitivity
(71.8%) and NPV (54.1%%) for detecting AF events > 6
min. A single 7-day monitor (a strategy commonly used in clinical
practice) had a low sensitivity (45.2% and 43.4%) and negative
predictive value (39.5% and 37%) for detecting AF events
> 6 min in patients with paroxysmal and persistent AF,
respectively. Heat maps showing daily AF burden within 1 year post
blanking period in patients with paroxysmal and persistent AF are shown
in Supplement Figure 1 and Supplement Figure 2, respectively.