Baseline characteristics
In
this study, 100 patients (48 men, mean age 62.77 ±14.10 years, and 52
women, mean age 60.00 ±13.15 years) who underwent successful ablation in
either the RVOT or the LVOT were enrolled. All these patients had taken
at least one antiarrhythmic drug, including metoprolol, propafenone, or
amiodarone. According to the successful ablation site, in 63 (63.00%)
patients, the VA had originated in the RVOT, and in 37 (37.00%)
patients, it had originated in the LVOT. The LVOT group comprised 14
(37.84%) patients with left coronary cusp (LCC), 9 (24.32%) patients
with right coronary cusp (RCC), 10 (27.03%) patients with left
ventricular endocardium below the aortic sinus cusp (ASC), and 4
(10.81%) patients with GCV-AIV.
Comparison
of the previous ECG parameterswithout
restrictions in thetransition
lead
In the previous
ECG
parameters, the V2 transition ratio, V3 R-wave deflection interval, and
V1–V3 transition index were used in the OTVAs, with the transition lead
in V3. The other seven parameters could be used in the OTVAs without
restrictions
in the transition lead. Therefore, the 100 patients with OTVAs were
analyzed with the other seven parameters
using
ROC
curve
analysis
(Figure 1A). The V2S/V3R index
(AUC
=
0.89,
p = 0.00)
was
superior to S-R difference in leads V1 and V2 (AUC = 0.87, p = 0.00) and
the TZ index
(AUC
=
0.75,
p = 0.00) in predicting the origin of the
RVOT.
Further, the larger ISA in leads V1 and V2
(AUC
= 0.90, p = 0.00) was superior to the larger R/S-wave amplitude index in
leads V1 and V2 (AUC = 0.87, p = 0.00), the larger R-wave duration index
in leads V1 and V2 (AUC = 0.84, p = 0.00), and the amplitude of the QRS
complex in the initial 40 ms in V2 (AUC = 0.65, p = 0.04) in predicting
the origin of the LVOT. Table 2 compares the accuracy, sensitivity,
specificity,
positive
predictive value (PPV), and negative predictive value (NPV) of the ECG
parameters for predicting the origin of the LVOT.
Among
the parameters,
the
V2S/V3R index
was
significantly
greater for VAs originating from the RVOT. The
Youden
index was 0.65, and the optimal cutoff value was 1.5 (Figure 1B).
Further, the accuracy was 81.00%, sensitivity was 79.37%, specificity
was 83.78%,
PPV
was 89.29%, and
NPV
was 70.45%.
The larger ISA in leads V1 and V2 was significantly greater for VAs
originating from the LVOT. The Youden index was 0.62, and the optimal
cutoff value was 57
ms
× mv (Figure 1C). The accuracy was 82.00%, sensitivity was 81.08%,
specificity was 82.54%, PPV was 73.17%, and NPV was 88.14%.
Comparison of the previous ECG parameterswith
the transition lead in V3
An additional ROC analysis (Figure 2A) for the previous 10 parameters
was performed among 37 (37.00%) patients with the transition lead in
V3.
The
V2S/V3R index
(AUC
=
0.82,
p = 0.01)
was
better than the S-R difference in leads V1 and V2 (AUC = 0.78, p = 0.02)
in predicting the origin of the RVOT.
Further,
the
V3
R-wave deflection interval
(AUC
= 0.81, p = 0.01) was better than
the
larger ISA in leads V1 and V2 (AUC = 0.77, p = 0.02) and larger R/S-wave
amplitude index in leads V1 and V2 (AUC = 0.77, p = 0.02) in predicting
the origin of the LVOT. The other parameters in predicting the origin of
VAs with the transition lead in V3 were not statistically
significant
(Table 3).
Among
the parameters, the V2S/V3R index was significantly greater for VAs
originating from the RVOT. The Youden index was 0.59, and the optimal
cutoff value was 1.5. The accuracy was 72.97%, sensitivity was 75.00%,
specificity was 72.00%, PPV was 56.25%, and NPV was 85.71%. On the
other hand, the V3 R-wave deflection interval
was
significantly greater for VAs originating from the LVOT.
The
Youden index was 0.73, and the optimal cutoff value was 80 ms (Figure
2B–2D). The accuracy was 86.49%, sensitivity was 75.00%, specificity
was 92.00%, PPV was 81.82%, and NPV was 88.46%.
Appropriate ECGalgorithm
for reliably predicting VA origin
For
VAs without restrictions in the transition lead, the algorithm (Figure
3) combining the V2S/V3R index and larger ISA index
could
predict VA origin with an accuracy
of
85.00%,
a
sensitivity of 75.68%, a specificity of 90.48%, a PPV of 82.35%, and
an NPV of 86.36%. For VAs with the transition lead in V3,
no
statistical significance was observed in the accuracy of predicting VA
origin between
the
V3 R-wave deflection interval
and
the
algorithm (86.49% vs. 85.00%, p = 0.528). Therefore, the algorithm can
reliably determine OTVA origin without restrictions in the transition
lead.