Pulsed Field Ablation of Atrial Fibrillation: An Initial Australian Single-Centre Experience.

BACKGROUND: Pulsed field ablation (PFA) is a newer ablation energy source with the potential to reduce complications and improve efficacy compared to conventional thermal atrial fibrillation (AF) ablation. This study aimed to present an initial single-centre Australian experience of PFA for AF ablation. METHODS: Initial consecutive patients undergoing PFA for paroxysmal or persistent AF at a single centre were included. Baseline patient characteristics, procedural data and clinical outcomes were collected prospectively at the time of the procedure. Patients were followed up at 3 months and 6-monthly thereafter. RESULTS: In total, 100 PFA procedures were performed in 97 patients under general anaesthesia. All pulmonary veins (403 of 403) were successfully isolated acutely. Median follow-up was 218 days (range, 16-343 days), and the Kaplan-Meier estimate for freedom from atrial arrhythmias at 180 days was 87% (95% confidence interval 79%-95%). Median procedure time was 74 minutes (range, 48-134 minutes). Median fluoroscopy dose-area product was 345 µGym2 (interquartile range, 169-685 µGym2). Two (2%) pseudoaneurysm vascular access complications occurred. There were no cases of thromboembolic complications, stroke, phrenic nerve palsy, pulmonary vein stenosis, atrio-oesophageal fistula, or pericardial tamponade. CONCLUSIONS: Pulsed field ablation can be performed safely and efficiently, with encouraging efficacy in early follow-up. Further data and clinical trials will be required to assess the comparative utility of PFA in contemporary AF ablation practice.

Consecutive Experience with Left Bundle Branch Area Pacing in a High-Volume Australian Centre.

INTRODUCTION: Left-bundle branch area pacing (LBBAP) is a relatively new technique for conduction system pacing. Australian safety and efficacy data is currently lacking. We aim to evaluate the learning curve, medium-term safety, and lead performance in a high-volume Australian setting. METHODS: We performed a retrospective cohort study of 200 consecutive LBBAP procedures performed by a single operator at two centres between January 2019 and May 2020. Left bundle branch area pacing was performed predominantly via left subclavian access using a 69 cm Medtronic SelectSecure 3830 pacing lead and a preformed non-steerable C315-His sheath. Procedural success was defined as evidence of left septal or left bundle branch area capture as evidenced by a right bundle branch block-like paced morphology. Procedural characteristics, and follow-up (including lead performance) data were collected. Procedural efficiency over time, as well as safety data, were collected. RESULTS: Median age was 78.26 years (interquartile range [IQR] 71-85), 37% were female. Atrial fibrillation was present in 22%. The left ventricular ejection fraction <50% in 24%, atrioventricular (AV) block was present in 43.5%, left bundle branch block in 22.5% and right bundle branch block in 24.5%. Acute procedural success was 91.5%. Implant threshold was 0.6V @ 0.5 ms, and 0.75V @ 0.5 ms at 11.9 months of follow-up. The QRS was significant reduced (baseline 134 ms vs implant 114 ms, p<0.001) There was a reduction in procedural time and X-ray dose over the course of the study. There were no complications specific to LBBAP. CONCLUSION: LBBAP appears to be a safe and effective pacing strategy. The QRS duration was significantly reduced compared to baseline. There appears to be an early learning curve with LBBAP.

Association of interventricular activation delay with clinical outcomes in cardiac resynchronization therapy.

BACKGROUND: Pacing at sites of longest interventricular delay has been associated with greater reverse remodeling in cardiac resynchronization therapy (CRT). However, the effects of pacing at such sites on clinical outcomes is less well studied. OBJECTIVE: The purpose of this study was to assess the association between interventricular delay and clinical outcomes in CRT patients implanted with quadripolar left ventricular (LV) leads. METHODS: RALLY-X4 was a registry study of the Acuity X4 quadripolar LV leads. Interventricular delay was measured during unpaced basal rhythm from the right ventricular (RV) lead to the LV lead electrode (E1 to E4) chosen for CRT pacing. Patients were stratified by median RV-LV delay (80 ms) into short and long delay groups; they also were analyzed by multivariable modeling. The primary composite outcome measure was all-cause mortality and heart failure hospitalization (HFH) at 18 months. RESULTS: A total of 581 patients had complete RV-LV delay data. Mean LV ejection fraction was 27%, and 73% had typical left bundle branch block. Predictors of long RV-LV delay included female sex, left bundle branch block, and QRS duration >150 ms. Survival free of the primary outcome at 18-month follow-up was 87% in the long activation delay group compared with 77% in the short delay group (P = .0042). Multivariate analysis showed that RV-LV delay was an independent predictor of survival free of HFH (P = .028). CONCLUSION: Among CRT patients with quadripolar LV pacing leads, longer baseline interventricular activation delay was significantly associated with the composite endpoint of all-cause mortality and HFH.

An innovative ovine model of severe cardiopulmonary failure supported by veno-arterial extracorporeal membrane oxygenation.

Refractory cardiogenic shock (CS) often requires veno-arterial extracorporeal membrane oxygenation (VA-ECMO) to sustain end-organ perfusion. Current animal models result in heterogenous cardiac injury and frequent episodes of refractory ventricular fibrillation. Thus, we aimed to develop an innovative, clinically relevant, and titratable model of severe cardiopulmonary failure. Six sheep (60 ± 6 kg) were anaesthetized and mechanically ventilated. VA-ECMO was commenced and CS was induced through intramyocardial injections of ethanol. Then, hypoxemic/hypercapnic pulmonary failure was achieved, through substantial decrease in ventilatory support. Echocardiography was used to compute left ventricular fractional area change (LVFAC) and cardiac Troponin I (cTnI) was quantified. After 5 h, the animals were euthanised and the heart was retrieved for histological evaluations. Ethanol (58 ± 23 mL) successfully induced CS in all animals. cTnI levels increased near 5000-fold. CS was confirmed by a drop in systolic blood pressure to 67 ± 14 mmHg, while lactate increased to 4.7 ± 0.9 mmol/L and LVFAC decreased to 16 ± 7%. Myocardial samples corroborated extensive cellular necrosis and inflammatory infiltrates. In conclusion, we present an innovative ovine model of severe cardiopulmonary failure in animals on VA-ECMO. This model could be essential to further characterize CS and develop future treatments.

Safety and Efficacy of Leadless Pacemakers: A Systematic Review and Meta-Analysis.

Background Leadless pacemaker is a novel technology, and evidence supporting its use is uncertain. We performed a systematic review and meta-analysis to examine the safety and efficacy of leadless pacemakers implanted in the right ventricle. Methods and Results We searched PubMed and Embase for studies published before June 6, 2020. The primary safety outcome was major complications, whereas the primary efficacy end point was acceptable pacing capture threshold (≤2 V). Pooled estimates were calculated using the Freedman-Tukey double arcsine transformation. Of 1281 records screened, we identified 36 observational studies of Nanostim and Micra leadless pacemakers, with most (69.4%) reporting outcomes for the Micra. For Micra, the pooled incidence of complications at 90 days (n=1608) was 0.46% (95% CI, 0.08%-1.05%) and at 1 year (n=3194) was 1.77% (95% CI, 0.76%-3.07%). In 5 studies with up to 1-year follow-up, Micra was associated with 51% lower odds of complications compared with transvenous pacemakers (3.30% versus 7.43%; odds ratio [OR], 0.49; 95% CI, 0.34-0.70). At 1 year, 98.96% (95% CI, 97.26%-99.94%) of 1376 patients implanted with Micra had good pacing capture thresholds. For Nanostim, the reported complication incidence ranged from 6.06% to 23.54% at 90 days and 5.33% to 6.67% at 1 year, with 90% to 100% having good pacing capture thresholds at 1 year (pooled result not estimated because of the low number of studies). Conclusions Most studies report outcomes for the Micra, which is associated with a low risk of complications and good electrical performance up to 1-year after implantation. Further data from randomized controlled trials are needed to support the widespread adoption of these devices in clinical practice.

Electrophysiologic and imaging evidence for an occult myopathic substrate in patients with idiopathic ventricular arrhythmias.

BACKGROUND: Idiopathic VA are traditionally considered benign, although occasional patients develop an ectopy-mediated cardiomyopathy (EMC). It is unclear whether patients with idiopathic VA in the absence of left ventricular (LV) dysfunction harbor a subclinical cardiomyopathy. We aim to assess for cardiomyopathic substrate in patients with idiopathic ventricular arrhythmias (VA) using imaging and electrophysiologic markers of early fibrosis. METHODS: Cardiac magnetic resonance (CMR) imaging and ventricular electroanatomic mapping was performed in 3 groups: patients undergoing ablation for idiopathic VA without (Group 1, n = 17) and with LV dysfunction (Group 2 [presumed EMC], n = 12) plus a control group undergoing ablation of supraventricular tachycardia (Group 3, n = 16). Global LV strain, T1 mapping and extended electrogram (EGM) characteristics were compared. RESULTS: Global strain was impaired in patients with presumed EMC (Group 2, p < 0.001). Native T1 times did not differ between groups, however patients in both idiopathic VA groups (Groups 1 and 2) had shorter post-contrast T1 times at 8 min compared to SVT controls (Group 3, p = 0.04). Similarly, the duration of the bipolar EGM was subtly prolonged in both Group 1 and 2 compared to Group 3 (p = 0.002). There were no between group differences in unipolar or bipolar voltage, the no. of bipolar EGM deflections or the maximal unipolar EGM dV/dt. CONCLUSION: Patients with idiopathic VAs and apparently structurally normal hearts may have subtle CMR and electrophysiologic changes similar in magnitude to that seen in frank presumed EMC, possibly suggestive of an occult cardiomyopathic process.

Right Ventricular Electrogram Characteristics in a T1 Mapping-Validated Normal Population: Implications for Unipolar Voltage Mapping.

OBJECTIVES: The aim of this study was to define normal ventricular electrographic characteristics in T1 mapping-validated normal patients using a contemporary contact force catheter. BACKGROUND: Reference values for human endocardial ventricular electrographic characteristics have not been defined using contemporary mapping equipment in patients without heart disease or ventricular arrhythmias. METHODS: Fourteen patients undergoing SVT ablation underwent mapping of the right ventricle and cardiac magnetic resonance imaging with T1 mapping. Electrograms (EGMs) from sites with >10 g of contact force from the right ventricular free wall (RVFW) and right ventricular septum (RVS) were analyzed. Values <5th percentile or >95th percentile were defined as abnormal. RESULTS: The median age was 27 years, 64% of patients were men, and the mean left ventricular ejection fraction was 60%. Native T1 values (mean 979 ms) of the study population were comparable with that of a normal volunteer population. Ninety-five percent of bipolar EGMs had <6 (RVFW) or <7 (RVS) deflections and duration <37 ms. Ninety-five percent of unipolar EGMs had a maximum dV/dt >0.23 mV/ms (RVFW) or >0.24 mV/ms (RVS). Ninety-five percent of unipolar EGMs had a peak-to-peak voltage >3.8 mV (RVFW) or >4.5 mV (RVS). CONCLUSIONS: In structurally normal hearts, the threshold for abnormal endocardial unipolar voltage in the RVFW (3.8 mV) is lower than that of the current standard (5.5 mV). The unipolar voltage characteristics of the RVS is distinct from that of the RVFW and left ventricle. This has implications for the detection of intramural or epicardial and especially midseptal scar.

Late Potentials and Early Repolarisation Are Associated With Serious Mental Illness and May Portend Increased Arrhythmic Risk.

BACKGROUND: Patients with serious mental illness (SMI) have an increased risk of sudden death. Higher rates of signal-averaged electrocardiogram (SAECG) abnormal late potentials (LP), which may be a predictor of sudden death risk, have been shown in patients with schizophrenia. We aimed to assess the prevalence and predictors of electrocardiograph (ECG) and SAECG abnormalities in a mixed SMI population. METHODS: Consecutive consenting inpatients with SMI had 12-lead ECG and SAECG recorded in addition to demographics, diagnoses and medications. Standard criteria for abnormal SAECG were applied. Multivariate regression analysis was performed to determine predictors of SAECG abnormalities including diagnoses, body mass index, ECG parameters, psychotropic medication use, and medications associated with Long QT or Brugada syndromes. RESULTS: Eighty (80) patients, 49% male, mean age 39±17 years were included. SAECG criteria abnormality for 1, 2 or 3 criteria were seen in 19, 3 and 5 cases (34% in total) respectively. Early repolarisation pattern was seen in 19% of patients. SAECG abnormality was associated with male gender (OR 7.3; 95% CI 2.3-23.4), and schizophrenia/schizoaffective disorder diagnosis (OR 7.4; 95% CI 1.9-29.0), but not with medication type or dose. CONCLUSIONS: In the mixed SMI population studied, there was a high rate of SAECG-detected late potentials (34%) and early repolarisation pattern (19%). Schizophrenia/schizoaffective disorder diagnosis was the strongest multivariate predictor identified. Further studies are needed to define the mechanism and significance of these cardiac abnormalities in SMI patients.

The Electrocardiographic Footprints of Ventricular Ectopy.

Ventricular ectopics, also known as ventricular extrasystoles, premature ventricular contractions or complexes (PVC) and ventricular premature depolarisations (VPD) are beats arising from within the ventricles. When they occur in groupings such as bigeminy, trigeminy, couplets and triplets they are referred to as ventricular ectopy. The electrocardiographic (ECG) footprints of a ventricular ectopic include a broad (>110 ms), premature, ventricular complex (QRS deflection); no evidence of pure atrioventricular (AV) conduction; a full, more than, or less than compensatory pause; and discordant QRS and T wave axis. Ventricular ectopy is a very common finding on Holter monitoring at all ages, but particularly in the elderly. In the otherwise normal heart, ventricular ectopy is generally infrequent and a benign finding, but in patients with heart disease, they may be a harbinger to more serious ventricular tachyarrhythmias. In this review, the range and manifestations of ventricular ectopy will be explored in detail with ECG examples.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias: Executive summary.

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias: executive summary.

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias.

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias: Executive summary.

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias: Executive summary.

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias.

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias.

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.