Electrocardiographic Features of Failed and Recurrent Right Ventricular Outflow Tract Catheter Ablation of Idiopathic Ventricular Arrhythmias Shinya Yamada, M.D.,1,2 Fa-Po Chung, M.D.1,3, Yenn-Jiang Lin, M.D., Ph.D.1,3, Shih-Lin Chang, M.D., Ph.D.1,3, Li-Wei Lo, M.D., Ph.D.1,3, Yu-Feng Hu, M.D., Ph.D.1,3, Ta-Chuan Tuan, M.D.1,3, Tze-Fan Chao, M.D.1,3, Jo-Nan Liao, M.D.1,3, Chung-Hsing Lin, M.D.1, Chin-Yu Lin, M.D.1,3, Yao-Ting Chang, M.D.1,3, Ting-Yung Chang, M.D.1,3, Abigail Louise D. Te, M.D.1, and Shih-Ann Chen, M.D.1,3

1

Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.;

2

Department of Cardiovascular Medicine, Fukushima Medical University, Fukushima, Japan; and

3

Department of Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan.

Short title: ECG features of failed RVOT-VA ablation

This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1111/jce.13359.

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*Address for correspondence

Shih-Ann Chen, M.D.

Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, No. 201, Sec. 2, Shih-Pai Road, Taipei, Taiwan.

Tel: 886-2-2875-7156

Fax: 886-2-2873-5656

E-mail: [email protected]

S.Yamada, MD and F-P Chung, MD contributed equally to this work.

Disclosures: None

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Abstract Introduction: Various ECG algorithms have been proposed to identify the origin of idiopathic outflow tract (OT)-ventricular arrhythmia (VA). However, electrocardiographic features of failed and recurrent right ventricular outflow tract (RVOT) ablation of idiopathic OT-VAs have not been clearly elucidated.

Methods and Results: A total of 264 consecutive patients (mean age: 44.0±13.0 years, 96 male) undergoing RVOT ablation for OT-VAs with a transition ≥ V3, including 241 patients (91.6%) with initially successful procedures and 23 patients (8.4%) with failed ablation. Detailed clinical characteristics and ECG features were analyzed and compared between the two groups. VAs with failed RVOT ablation had larger peak deflection index (PDI), longer V2 R wave duration (V2Rd), smaller V2 S wave amplitude, higher R/S ratio in V2, higher V3 R wave amplitude, and larger V2 transition ratio than those with successful ablation. Multivariate analysis demonstrated that PDI, V2Rd, V2 transition ratio, and pacemapping score acquired during mapping independently predicted failed ablation (P=0.01, P=0.01, P=0.01, and P250 seconds. In the RVOT and subvalvular area, radiofrequency energy was delivered in a temperature-controlled mode at 50-60 ºC with pulse duration of 60 seconds for each point; maximal power was 50 W for the nonirrigated catheter and 30–35 W for the irrigated catheter, targeting for an impedance decrease of 10 Ω. If the VA was suppressed within 30 seconds, radiofrequency energy would be maintained for a total of 120-300 seconds. Repeat mapping was performed if VA suppression and/or elimination was not observed. In the aortic cusps and GCV/ AIV area, RF energy was delivered through a temperature-controlled mode at 30–40ºC with a pulse duration of 30 seconds while targeting an

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impedance drop of 10 Ω. If the VA was suppressed within 30 seconds, RF energy would be maintained for a total of 40 seconds and additional energy would be applied up to a maximum of 3 burns. Acute procedural success was defined as complete elimination of spontaneous or inducible VAs under the infusion of isoproterenol (up to 5 μg/min), following the same induction protocol for 30 minutes to exclude acute recurrences. The successful ablation site was defined by the point with an elimination of targeted VA with radiofrequency energy application. Patients with failed ablation were defined as those without effects on the VA burden during the application of radiofrequency energy or those with acute recurrences after stopping radiofrequency energy.

ECG analysis of the VA morphology

Sinus rhythm and VA ECG morphology were measured on the BARD recording system, with the recordings displayed at a sweep speed of 100 and 200 mm/s. Standard 12-lead ECG electrode placement was used. The following measurements were assessed on the surface ECG of the first beat of VT or the PVCs: (1) QRS duration; (2) R-wave amplitude and the duration from the onset of QRS to the peak of QRS deflection in lead II, III, aVF; (3) R-wave ratio of leads III/II;17 (4) Q-wave amplitude in leads aVL and aVR; (5) R- and S-wave amplitudes in leads V1 to V3; (6) R-wave

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duration in leads V1 to V3; (7) aVL/aVR Q wave ratio; (8) R/S ratio in leads V1 to V3; (9) V2S/V3R index;13 (10) V2 transition ratio;10 (11) peak deflection index (PDI);18 (12) precordial transition in left bundle branch block morphology. During the sinus beats, R- and S-wave amplitudes in lead V2 were also measured on the surface ECG (Figure 1).

Definition of the ECG criteria

PVC QRS duration

The PVC QRS duration (ms) was defined as the interval measured from the earliest ventricular activation (or from the stimulation artifact) to the offset of the QRS complex in the precordial leads.

Coupling interval

The coupling interval (ms) was measured from the beginning of a normal QRS complex to the beginning of the PVC.

Peak QRS duration

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The peak QRS duration (ms) was defined as the time from the QRS onset to the peak QRS deflection in the inferior leads.

R wave duration

The R wave duration (ms) was determined in the precordial leads from the QRS onset to the R wave transaction point of the R wave with an isoelectric line.

V2 transition ratio

The V2 transition ratio was calculated in V2 by dividing the R-wave percentage during VT (R/R + S)VA by the R-wave percentage during sinus rhythm (R/R + S)sinus.10

V2S/V3R index

The V2S/V3R index was defined as the S-wave amplitude in V2 divided by the R-wave amplitude in V3 during the VA.13

Peak deflection index (PDI)

The PDI was defined as the inferior lead presenting the tallest R wave by dividing the time from the QRS onset to the peak QRS deflection by the total QRS duration.18

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Clinical Follow-up

Patients were followed as described previously.9, 12, 15 In brief, patients were followed up in the cardiology outpatient clinic with 12-lead ECGs, 24-hour Holter monitoring, and echocardiography after RFCA every 3 months for the first half year and then 6 months thereafter. For patients who could not come for outpatient follow-up in our institution, they were contacted over telephone for recurrent symptoms and recurrent arrhythmias. These patients were also advised to visit our affiliated institutions to complete follow-up screening and the medical reports were obtained from these affiliated institutions. The recurrence was defined as recurrence of greater than 1000 ventricular PVCs, nonsustained VT or sustained VT, as confirmed by morphology criteria using 24-hour Holter monitoring.

Statistical analysis

Data are expressed as mean and standard deviation for normally distributed continuous variables and proportions for categorical variables. Continuous variables were analyzed using a

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two-tailed t-test. Discrete variables were compared using a chi-square (χ2) test. The association between selected parameters and the failed RVOT RFCA was studied by linear regression analysis. The variables selected for testing in multivariate analysis were those with a P

Electrocardiographic features of failed and recurrent right ventricular outflow tract catheter ablation of idiopathic ventricular arrhythmias.

Various ECG algorithms have been proposed to identify the origin of idiopathic outflow tract (OT)-ventricular arrhythmia (VA). However, electrocardiog...
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