Results
Twenty-five patients underwent first-time PVI as described, between
November 2016 and May 2017: 13 persistent AF, 12 PAF; 19 male (76%);
mean age 57 [SD: 14] years and mean
CHA2DS2-VASc score 1.3 [SD: 1.3].
Complete PVI was achieved in all without spontaneous / dormant recovery
of PV conduction, following mean 16.2 [SD: 3.1] minutes of RF,
without procedural complications. The respiratory motion-triggering
cohort comprised 8 cases (32%); considering age, body mass index and RF
duration required for case completion, there were no significant
differences between cohorts with and without respiratory motion
threshold triggering.
Comparing ACCURESP™ RMA “on” versus “off”, the number of
auto-annotated LAPW sites and total LAPW RF duration were 82 and 98, and
1091s and 1006s, respectively. Annotated RF data according to RMA
setting are shown in table 1. For each group (i.e. left or right-sided),
per-site RF duration and FTI were significantly greater with RMA “on”
versus “off”: i.e. left-sided mean RF duration 13.1s versus 9.9s
(p=0.0003) and median FTI 156g.s versus 114g.s (p=0.0003), respectively;
right-sided mean RF duration 13.5s versus 10.6s (p=0.006) and median FTI
228g.s versus 166g.s (p=0.04), respectively. Analysis combining left and
right sides also demonstrated significantly greater mean ITD with RMA
“on”; i.e. 6.0mm versus 4.8mm (p=0.002).
Table 2 shows comparisons of annotated RF data at site-1 according to
RMA setting: At the left-side and comparing ACCURESP™ RMA “on” versus
“off” the site 1-to-2 ITD (6.6mm versus 5.3mm, p=0.07), RF duration
(16.0s versus 15.1s, p=0.16) and FTI (185g.s versus 163g.s, p=0.33) were
greater with RMA “on”, but without statistical significance. At the
right side the site 1-to-2 ITD was greater with RMA “on” (7.2mm versus
5.0mm, p=0.13), but without statistical significance. Combined data
analysis demonstrated that auto-annotated site 1-to-2 ITD was
significantly greater with RMA “on” versus “off” (i.e. 6.7mm versus
5.2mm, p=0.02), while the difference in site-1 RF duration (15.7s versus
15.1s, p=0.09) and FTI (240g.s versus 198g.s, p=0.38) was not
statistically significant.
Analyses at sites of deliberate catheter motion: Auto-annotated
site 1-to-2 transitions
Comparing auto-annotated data (RMA “on” minus “off”) at 3 site
1-to-2 transitions concurrent with loss of tissue contact (i.e. 0g CF),
the maximum difference in RF duration, FTI and ITD was -0.6s, -17g.s and
2.2mm respectively, with no difference in impedance drop (table 3 and
figure 1, plus supplementary figures 1-2).
Four site 1-to-2 transitions were effected with constant catheter-tissue
contact and associated with UE morphology change from pure R (site-1
completion) to RS (site-2 onset). In this group, the maximum difference
(RMA “on” minus “off”) in RF duration, FTI, ITD and impedance drop
was 11.3s, 139g.s, 2.6mm and 3.3Ω respectively (table 3), with the first
indication of catheter movement represented via RMA “off” annotation
in all cases (figure 2 and supplementary figures 3-5). The greatest
difference occurred when site 1-to-2 ITD with RMA “off” was 4.1mm
(figure 2): at 15.2s following RF onset there was an abrupt increase in
catheter position shift and SD, with a corresponding change in CF
waveform indicating deliberate catheter motion “per protocol” at 15s,
however while annotated site 1-to-2 transition according to RMA “off”
coincided with these changes (blue vertical line), the RMA “on” timing
of annotated site 1-to-2 transition occurred 11.3s later (red vertical
line).
The remaining 9 deliberate site 1-to-2 transitions during constant
catheter-tissue contact were associated with continuous pure R UE
morphology at both site-1 end and site-2 onset. Comparison of annotated
data (RMA “on” minus “off”) demonstrated a difference in site-1 RF
duration >1s in 8; range -1.3 – 8.6s, mean 3.7 [SD:
4.0] s (supplementary table 1). In this group, maximal differences in
site-1 annotated RF duration, FTI, ILD and impedance drop were 8.6s,
208g.s, 7.7mm and 1.4Ω respectively, with RMA “on” resulting in
greater values for annotated data in 7/9 transitions. When considering
multiple measures of catheter position stability, the appropriate
indication of deliberate catheter motion occurred with RMA “off” in
all 9 transitions; 8/9 demonstrated ≥1s difference in annotation timing
(supplementary figure 13).
For all 13 deliberate site 1-to-2 transitions achieved with constant
catheter-tissue contact, the relationship between differences in
annotated RF data (RMA “on” minus “off”) and ITD (with RMA “off”)
is shown in figure 3. There was a strong negative correlation between
the difference in annotated RF duration and ITD – Pearson r -0.68 (95%
confidence interval (CI) -0.91 to -0.13, p=0.02). Consequently, while
the maximum difference in annotated RF duration with ≥6mm site 1-to-2
ITD was 1.1s, ≤5mm ITD was associated with maximal difference in
annotated RF duration of 11.3s. There was a moderate negative
correlation between the difference in annotated FTI and ITD – Pearson r
-0.47 (95% CI -0.81 to 0.11, p=0.10) and a moderate negative
correlation between the difference in impedance drop and ITD – Pearson
r -0.53 (95% CI -0.84 to 0.05, p=0.07).
Data supplement figures 7 – 15 demonstrate remaining annotated site
1-to-2 transitions, with corresponding position shift, SD, CF and
impedance data.