Position Statement on the Management of Cardiac Electrophysiology and Cardiac Implantable Electronic Devices in Australia During the COVID-19 Pandemic: A Living Document.

The COVID-19 pandemic poses a significant stress on health resources in Australia. The Heart Rhythm Council of the Cardiac Society of Australia and New Zealand aims to provide a framework for efficient resource utilisation balanced with competing risks when appropriately treating patients with cardiac arrhythmias. This document provides practical recommendations for the electrophysiology (EP) and cardiac implantable electronic devices (CIED) services in Australia. The document will be updated regularly as new evidence and knowledge is gained with time.

Analysis of local ventricular repolarization using unipolar recordings in patients with arrhythmogenic right ventricular cardiomyopathy.

PURPOSE: In arrhythmogenic right ventricular cardiomyopathy (ARVC), abnormal electroanatomic mapping (EAM) areas are proportional to extent of T-wave inversion on 12-lead ECG. We aimed to evaluate local repolarization changes and their relationship to EAM substrate in ARVC. METHODS: Using unipolar recordings, we analyzed the proportion of negative T waves ≥ 1 mV in depth (NegT), NegT area, Q-Tpeak (QTP), Tpeak-Tend (TPE) intervals and their relationship to bipolar (< 1.5 mV ENDO, < 1.0 mV EPI) and unipolar (< 5.5 mV) endocardial (ENDO) and epicardial (EPI) low-voltage area (LVA) in 21 pts. (15 men, mean age 39 ± 14) with ARVC. Control group included 5 pts. with normal hearts and idiopathic PVCs. RESULTS: On ENDO, the % of NegT (7 ± 5% vs 30 ± 20%, p = 0.004) and the NegT area (12.9 ± 9.7 c m2 vs 61.4 ± 30.0 cm2, p = 0.001) were smaller in ARVC compared to controls. On EPI, the % of NegT was similar (5 ± 7% vs 3 ± 4%, p = 0.323) and the NegT area, larger (11.0 ± 8.4 cm2 vs 2.7 ± 0.9 cm2, p = 0.027) in ARVC group. In ARVC group, the % of NegT area inside LVA was larger on EPI compared to ENDO for both bipolar (81 ± 27% vs 31 ± 33%, p < 0.001) and unipolar (90 ± 19% vs 73 ± 28%, p = 0.036) recordings. Compared to normal voltage regions, QTP inside ENDO abnormal LVA was on average 58 ± 26 ms shorter and TPE, 25 ± 56 ms longer (97 ± 26 ms and 56 ± 86 ms on EPI, respectively). CONCLUSIONS: In ARVC, NegT areas are more closely associated with abnormal depolarization LVA on the EPI and QTP is shorter and TPE longer inside ENDO and EPI abnormal LVA compared to normal voltage regions. The results add to our understanding of ARVC arrhythmia substrate.

Bundle branch reentrant ventricular tachycardia: review and case presentation.

Bundle branch reentrant ventricular tachycardia (BBRVT) is characterized by a unique, fast (200-300 beats/min), monomorphic wide complex tachycardia (WCT) associated with syncope, hemodynamic compromise, and cardiac arrest. It is challenging to diagnose, requiring a His bundle recording and specific pacing maneuvers. The overall incidence has been reported to be up to 20% among patients with non-ischemic cardiomyopathy (NICM) undergoing electrophysiologic studies. We report a case of BBRVT in a patient with ischemic cardiomyopathy (ICM) presenting as a WCT with recurrent implantable-cardioverter-defibrillator (ICD) shocks. We describe all the characteristic features of BBRVT and discuss its differential. We also discuss the role of ablation for this condition.

Outcomes of Catheter Ablation of Idiopathic Outflow Tract Ventricular Arrhythmias With an R Wave Pattern Break in Lead V2: A Distinct Clinical Entity.

INTRODUCTION: In outflow tract ventricular arrhythmias (OT-VAs), an abrupt loss of the R wave in lead V2 compared to V1 and V3 (pattern break in V2-PBV2) suggests an origin close to the anterior interventricular sulcus (anatomically opposite to lead V2) and adjacent to proximal coronaries. We studied the outcome of catheter ablation of OT-VAs with a PBV2. METHODS AND RESULTS: Of 130 consecutive patients with idiopathic left bundle block morphology OT-VAs and transition ≤V4, 12 (9%) had PBV2. Outcomes in this group were compared to the remaining 118 patients. Patients with PBV2 were more likely to be younger (41 ± 18 vs. 50 ± 14 years, P = 0.0384) and women (11 [92%] vs. 70 [59%], P = 0.0302). The earliest activation was at the RVOT in seven, left coronary cusp (LCC) in one, anterior interventricular vein (AIV) in two and the epicardium in two. In five (42%) cases (earliest activation in the AIV in two, epicardium in two, and RVOT below the valve level in one), ablation was aborted due to proximity to the left anterior descending (LAD) coronary artery. After 36 ± 17 months and 1.3 ± 0.5 procedures, VAs elimination was achieved in 58% of patients with PBV2 compared to 89% of the reference population (P = 0.0125) with effective site in five of seven at the most anterior and leftward RVOT adjacent to the pulmonic valve (PV). CONCLUSIONS: OT-VAs with PBV2 demonstrate a unique ECG pattern and challenging catheter ablation. Proximity to LAD precludes ablation in about half. Long-term VA suppression could be achieved in only 58% of cases most commonly when the earliest site is at the anterior and leftward RVOT just under the PV.

Distinct Electrocardiographic Form of Idiopathic Ventricular Arrhythmia Originating From the Left Bundle Branch.

Most premature ventricular contractions (PVCs) arise from the right or left ventricular outflow tract. Some VPCs originate near the His-bundle region. However, there remains a paucity of information on PVCs originating directly from the cardiac conduction system. We describe 2 cases with idiopathic frequent PVCs that were mapped directly to the left bundle branch itself. We also provide an anatomic-based mapping and ablation approach for management of these uncommon and challenging arrhythmias. In both cases we were able to either eliminate or significantly suppress the ectopic source by applying radiofrequency at this location without causing any significant impairment of the atrioventricular conduction.

Ventricular arrhythmias associated with left ventricular noncompaction: Electrophysiologic characteristics, mapping, and ablation.

BACKGROUND: Left ventricular noncompaction (LVNC) is a primary cardiomyopathy that can present with recurrent ventricular arrhythmias (VAs). Data on the benefit of catheter ablation of VAs in LVNC are lacking. OBJECTIVE: The purpose of this study was to describe the electrophysiologic features and outcomes of catheter ablation of VAs in LVNC. METHODS: The cohort consisted of 9 patients (age 42 ± 15 years) with diagnosis of LVNC based on established criteria and VA (ventricular tachycardia [VT] in 3 and frequent premature ventricular contractions (PVCs) in 6) despite treatment with a mean of 2 ± 1 antiarrhythmic drugs. Ablation sites were identified using a combination of entrainment, activation, late/fractionated potential ablation, and pace-mapping. RESULTS: A total of 8 patients (89%) had left ventricular (LV) systolic dysfunction (mean ejection fraction 40% ± 13%). Patients who presented with VT had evidence of abnormal electroanatomic substrate involving the mid- to apical segments of the LV, which matched the noncompacted myocardial segments identified by preprocedural magnetic resonance imaging or echocardiography. In patients presenting with frequent PVCs, the site of origin was identified at the papillary muscles (50%) and/or basal septal regions (67%). After median follow-up of 4 years (range 1-11) and a mean of 1.8 ± 1.1 procedures, VAs recurred in 1 patient (11%). Significant improvement in LV function occurred in 4 of 8 cases (50%). No patients died or underwent heart transplantation. CONCLUSION: The VA substrate in patients with LVNC and VT typically involves the mid-apical LV segments, whereas focal PVCs often arise from LV basal-septal regions and/or papillary muscles. Catheter ablation is safe and effective in achieving good VA control over long-term follow-up in most patients.

Comparison of Left Atrial Bipolar Voltage and Scar Using Multielectrode Fast Automated Mapping versus Point-by-Point Contact Electroanatomic Mapping in Patients With Atrial Fibrillation Undergoing Repeat Ablation.

INTRODUCTION: Bipolar voltage criteria to delineate left atrial (LA) scar have been derived using point-by-point (PBP) contact electroanatomical mapping. It remains unclear how PBP-derived LA scar correlates with multielectrode fast automated mapping (ME-FAM) derived scar. We aimed to correlate scar and bipolar voltages from LA maps created using PBP versus ME-FAM. METHODS AND RESULTS: In consecutive patients undergoing repeat AF ablation, 2 separate LA maps were created using PBP and ME-FAM during sinus rhythm before ablation. Contiguous areas in the LA with a bipolar voltage cutoff of ≤0.2 mV represented dense scar; LA scar percentage was calculated for each map. Each LA shell was divided into 9 regions and each region further subdivided into 4 quadrants for additional analysis; mean voltages of all points obtained using PBP versus ME-FAM in each region were compared. Forty maps (20 PBP: mean 228.5 ± 95.6 points; 20 ME-FAM: 923.0 ± 382.6 points) were created in 20 patients. Mapping time with ME-FAM was shorter compared with PBP (13.3 ± 5.3 vs. 34.4 ± 13.1 minutes; P < 0.001). Mean LA scar percentage was higher with PBP compared with ME-FAM (15.5 ± 17.1% vs. 12.8 ± 17.6%; P = 0.04). Mean PBP voltage distribution was lower (compared with ME-FAM) in the septum (0.95 ± 0.73 vs. 1.46 ± 0.99 mV; P = 0.009), posterior wall (0.84 ± 0.42 vs. 1.40 ± 0.83 mV; P = 0.0008), roof (0.78 ± 0.80 vs. 1.39 ± 1.09 mV; P = 0.0003), and right PV-LA junction (0.34 ± 0.25 vs. 0.59 ± 0.50 mV; P = 0.01) regions, while voltages were similar in all other LA regions (all P > 0.05). CONCLUSIONS: In AF patients undergoing repeat ablation, bipolar voltage is greater in certain LA segments with ME-FAM compared with PBP mapping.