Results
Baseline characteristics
A total of 136 patients were included in the study and 68 patients were
each allocated in the ME group and the control group. According to SVT
diagnosis, there were 76 patients with AVNRT (38 in the ME group and 38
in the control group) and 60 patients with AVRT/WPW syndrome (30 in the
ME group and 30 in the control group). The mean age was 51.2 (±16.7)
years and 76 (55.9%) patients were male (Table 1). There was no
significant difference in demographic characteristics or underlying
comorbidities between the ME group and the control group.
Procedure outcomes in the entire population
Ablation procedures were successfully conducted in all patients with no
intraprocedural complication. There was no crossover in ablation
catheters during the procedures. RF attempt number to achieve the
prespecified ablation endpoints was significantly lower in the ME group
compared to the control group (2 [1–4] vs. 3 [2–7] in the ME
group and the control group, respectively, p=0.032). RFA time to the
ablation endpoints was also significantly shorter in the ME group (23.5
[5.0–111.5] vs. 64.5 [16.0–185.0] seconds in the ME group and
the control group, respectively, p=0.013) (Table 2). During the entire
procedure, total ablation time and procedure time were similar between
the two groups. Average RF power was higher in the ME group (34.0
[31.0–38.0]W vs. 32.0 [28.0–33.5]W, p<0.001) and
average temperature was lower in the ME group (41.0 [34.0–42.0]°C
vs. 49.0 (46.0–51.5)°C, p<0.001). There was no significant
difference in the acute SVT reinduction rate between the two groups
(5.9% vs. 5.9%). The procedure endpoint (≤1 echo beat or an absence of
AP conduction) was achieved by repeated ablation in all patients with
SVT reinduction.
Outcomes in AVNRT
SP ablation was performed in 76 patients with AVNRT. Eight patients had
atypical AVNRT without significant difference between the two groups
(Table 3). Median RF attempt number to the emergence of junctional
rhythm was 2 (1–4) in the ME group and 2 (2–4) in the control group
(p=0.113) (Table 3). Median ablation time to the emergence of junctional
rhythm was 16 (5–80) seconds in the ME group and 48 (16–144) seconds
in the control group (p=0.043). There was no significant difference in
total ablation time, procedure time, or acute AVNRT reinduction rates
between the two groups. Discrete SP electrograms were observed via
ablation catheter in 14/38 (36.8%) patients in the ME group and 6/38
(15.7%) patients in the control group (Figure 2A). There was no
transient or persistent atrioventricular block after ablation in all
subjects.
Outcomes in AVRT/WPW syndrome
AP ablation was performed in 60 patients with AVRT/WPW syndrome.
Manifest AP was shown in 18 patients without significant difference
between the two groups (Table 4). Median RF attempt number to AP block
was 2.5 (1–5) in the ME group and 4 (2–9) in the control group
(p=0.128). Median ablation time to AP block was 29 (3–123) seconds in
the ME group and 82.5 (16–214) seconds in the control group (p=0.110)
(Table 4). There was no significant difference in total ablation time or
procedure time. SVT reinduction was not observed in all patients, and
acute AP reconnection rate (23.3% vs. 20.0% in the ME group and the
control group, respectively, p=1.000) and dormant AP conduction rate
(10.0% vs. 6.7%, p=1.000) were not significantly different between the
two groups. Discrete AP electrograms were observed via ablation catheter
in 13/30 (43.3%) patients in the ME group and 7/30 (23.3%) patients in
the control group (Figure 2B, 2C, 2D).