Observable Atrial and Ventricular Fibrillation Episode Durations Are Conformant With a Power Law Based on System Size and Spatial Synchronization.

BACKGROUND: Atrial fibrillation (AF) and ventricular fibrillation (VF) episodes exhibit varying durations, with some spontaneously ending quickly while others persist. A quantitative framework to explain episode durations remains elusive. We hypothesized that observable self-terminating AF and VF episode lengths, whereby durations are known, would conform with a power law based on the ratio of system size and correlation length ([Formula: see text]. METHODS: Using data from computer simulations (2-dimensional sheet and 3-dimensional left-atrial), human ischemic VF recordings (256-electrode sock, n=12 patients), and human AF recordings (64-electrode basket-catheter, n=9 patients; 16-electrode HD-grid catheter, n=42 patients), conformance with a power law was assessed using the Akaike information criterion, Bayesian information criterion, coefficient of determination (R2, significance=P<0.05) and maximum likelihood estimation. We analyzed fibrillatory episode durations and [Formula: see text], computed by taking the ratio between system size ([Formula: see text], chamber/simulation size) and correlation length ([Formula: see text], measured from pairwise correlation coefficients over electrode/node distance). RESULTS: In all computer models, the relationship between episode durations and [Formula: see text] was conformant with a power law (Aliev-Panfilov R2: 0.90, P<0.001; Courtemanche R2: 0.91, P<0.001; Luo-Rudy R2: 0.61, P<0.001). Observable clinical AF/VF durations were also conformant with a power law relationship (VF R2: 0.86, P<0.001; AF basket R2: 0.91, P<0.001; AF grid R2: 0.92, P<0.001). [Formula: see text] also differentiated between self-terminating and sustained episodes of AF and VF (P<0.001; all systems), as well as paroxysmal versus persistent AF (P<0.001). In comparison, other electrogram metrics showed no statistically significant differences (dominant frequency, Shannon Entropy, mean voltage, peak-peak voltage; P>0.05). CONCLUSIONS: Observable fibrillation episode durations are conformant with a power law based on system size and correlation length.

P-Wave Morphology From Common Nonpulmonary Vein Trigger Sites Following Pulmonary Vein and Posterior Wall Isolation.

BACKGROUND: Non-pulmonary vein (PV) triggers are increasingly targeted during atrial fibrillation (AF) ablation. P-wave morphology (PWM) can be useful because point mapping of AF triggers is challenging. The impact of prior ablation on PWM is yet to be determined. OBJECTIVES: This study sought to report PWM before and after left atrial (LA) ablation and construct a P-wave algorithm of common non-PV trigger locations. METHODS: This multicenter, prospective, observational study analyzed the paced PWM of 30 patients with persistent AF undergoing pulmonary vein isolation (PVI) and posterior wall isolation (PWI). Pace mapping was performed at the SVC, crista terminalis, inferior tricuspid annulus, coronary sinus ostium, left septum, left atrial appendage, Ligament of Marshall, and inferoposterior LA. The PWM was reported before PVI, then blinded comparisons were made post-PVI and post-PVI + PWI. A P-wave algorithm was constructed. RESULTS: A total of 8,352 paced P waves were prospectively recorded. No significant changes in the PWM were seen post-PVI alone in 2,775 of 2,784 (99.7%) and post-PWI in 2,715 of 2,784 (97.5%). Changes in PWM were predominantly at the IPLA (53 P waves) with a positive P-wave in leads V2 to V6 before biphasic post-PWI, LA appendage (9 P waves), coronary sinus ostium (6 P waves), and ligament of Marshall (3 P waves). A PWM algorithm was created before PVI and accurately predicted the location in 93% post-PVI + PWI. CONCLUSIONS: Minimal change was observed in PWM post-PV and PWI aside from the IPLA location. A P-wave algorithm created before and applied after PVI + PWI provided an accuracy of 93%. PWM provides a reliable tool to guide the localization of common non-PV trigger sites even after PV and PWI.

His bundle combined with deep septal left bundle branch area pacing for atrial fibrillation prior to atrioventricular node ablation.

Background: To mitigate the risk of dyssynchrony-induced cardiomyopathy, international guidelines advocate His bundle pacing (HBP) with a ventricular backup lead prior to atrioventricular node ablation in treatment-refractory atrial fibrillation and normal left ventricular ejection fraction. As a result of concerns with long-term pacing parameters associated with HBP, this case series reports an adopted strategy of HBP combined with deep septal left bundle branch area pacing (dsLBBAP) in this patient cohort, enabling intrapatient comparison of the two pacing methods. Methods and Results: Eight patients aged 72 ± 10 years (left ventricular ejection fraction 53 ± 4%) underwent successful combined HBP and dsLBBAP implant prior to AV node ablation. Intrinsic QRS duration was 118 ± 46 ms. When compared to dsLBBAP, HBP had lower sensed ventricular amplitude (2.4 ± 1.1 vs. 15 ± 5.3 V, p = .001) and lower lead impedance (522 ± 57 vs. 814 ± 171ohms, p = .02), but shorter paced QRS duration (101 ± 20 vs. 119 ± 17 ms, p = .02). HBP pacing threshold was 1.0 ± 0.6 V at 1 ms pulse width, and dsLBBAP pacing threshold was 0.5 ± 0.2 V at 0.4 ms pulse width. Five patients underwent cardiac CT showing adequate dsLBBAP ventricular septal penetration (8.6 ± 1.3 mm depth, 2.4 ± 0.5 mm distance from left ventricular septal wall). No complications occurred during a mean follow-up duration of 121 ± 92 days. Conclusions: Combined HBP and dsLBBAP pacing is a feasible approach as a pace and ablate strategy for atrial fibrillation refractory to medical therapy.

Clinical, electroanatomic and electrophysiologic characterization and outcomes of catheter ablation for ventricular tachycardia following valvular intervention.

INTRODUCTION: Ventricular tachycardia (VT) can occur following valvular interventions. There are limited data describing substrate and ablation approaches in such patients. We sought to describe the clinical, electrophysiologic, electroanatomic features and catheter ablation outcomes of patients with VT following aortic and/or mitral valve intervention. METHODS: Over 12-years, consecutive patients with aortic valve replacement (AVR) and/or mitral valve replacement (MVR) or repair, undergoing VT ablation, were identified from two centers. Clinical and procedural parameters and outcomes are described. RESULTS: Twenty-three patients (age 66 ± 14years, 78% male, left ventricular ejection fraction 37 ± 16%), with prior AVR (mechanical n = 6, bioprosthetic n = 2, transcatheter n = 1), MVR (mechanical n = 5, bioprosthetic n = 1), mitral valve repair (n = 6) and both mechanical AVR and MVR (n = 2), underwent VT ablation. Sixteen had concurrent ischemic cardiomyopathy, 10 with prior bypass surgery. Left ventricular access was obtained in 21/23 (91%) patients (transseptal n = 14, retrograde aortic n = 5, transapical n = 2), with perivalvular scar identified in 17/21 (81%). Re-entrant VT isthmi involved the perivalvular regions in 12/23 (52%) patients, and regions remote from the valve in the remainder; 9% had nonscar-related VT. Intramural substrate was ablated from adjacent chambers in 5/23 (22%) patients and with half-normal saline irrigation in 8/23 (35%) patients. There were no instances of catheter entrapment. Following final ablation, VA-free survival was 78% at 13-months. CONCLUSION: Only half of VT circuits following valvular interventions involve the valve regions themselves, while the remainder involves unrelated regions. Catheter ablation is safe and efficacious at treating VT following valvular intervention, but novel strategies may be required.

Percutaneous Mitral Valve Repair in Patients with Severe Mitral Regurgitation and Acute Decompensated Heart Failure.

The role of percutaneous mitral valve repair (PMVr) in management of high-risk patients with severe mitral regurgitation (MR) and acute decompensated heart failure (ADHF) is undetermined. We screened all patients who underwent PMVr between October 2015 and March 2020. We evaluated immediate, 30-day, and 1-year outcomes in patients who underwent PMVr during hospitalization due to ADHF as compared to elective patients. From a cohort of 237 patients, we identified 46 patients (19.4%) with severe MR of either functional or degenerative etiology who underwent PMVr during index hospitalization due to ADHF, including 17 (37%) critically ill patients. Patients' mean age was 75.2 ± 9.8 years, 56% were males. There were no differences in background history between ADHF and elective patients. Patients with ADHF were at higher risk for surgery, reflected in higher mean EuroSCORE II, compared with elective patients. After PMVr, we observed higher 30-day mortality rate in ADHF patients as compared to the elective group (10.9% vs. 3.1%, respectively, p = 0.042). One-year mortality rate was similar between the groups (21.7% vs. 17.9%, p = 0.493). Clinical and echocardiographic follow-up showed improvement of NYHA functional class and sPAP reduction in both groups ((54 ± 15 mmHg to 50 ±15 in the elective group (p = 0.02), 58 ± 13 mmHg to 52 ± 12 in the ADHF group (p = 0.02)). PMVr could be an alternative option for treatment of patients with severe MR and ADHF.

P-Wave Morphology in Focal Atrial Tachycardia: An Updated Algorithm to Predict Site of Origin.

OBJECTIVES: This study sought to report P-wave morphology (PWM) from a series of paraseptal (PS) atrial tachycardia (AT), revise then prospectively evaluate a simplified PWM algorithm against a contemporary consecutive cohort with focal AT. BACKGROUND: The 2006 PWM algorithm was useful in predicting the origin of focal AT. An updated algorithm was developed given advances in multipolar 3-dimensional mapping, potential limitations of PWM in separating PS sites, and a renewed interest in the P-wave in mapping non-pulmonary vein triggers. METHODS: The PWM from a consecutive series of 67 patients with PS AT were analyzed. PS sites included were coronary sinus ostium, perinodal, left and right septum, septal tricuspid annulus, superior mitral annulus, and noncoronary cusp. Next the P-wave algorithm was revised and prospectively evaluated by 3 blinded assessors. RESULTS: The P-wave for PS sites was neg/pos (n = 50), iso/pos (n = 10), or isoelectric (n = 4) in lead V1 (96%). The P-wave algorithm was modified and prospectively applied to 30 consecutive patients with focal AT who underwent successful ablation. Foci (n = 30) originated from the right atrium (33.3%), left atrium (30%), and PS (36.7%). Using the PW algorithm, the correct anatomic location was identified in 93%. Incorrect interpretation of the terminal positive P-wave component (n = 3) and initial negative P-wave deflection (n = 1) in lead V1 misidentified 4 paraseptal cases. CONCLUSIONS: The revised PWM algorithm offers a simplified and accurate method of localizing the responsible site for focal AT. The P-wave remains an important first step in mapping atrial arrhythmias.

Relationship between procedural volume and complication rates for catheter ablation of atrial fibrillation: a systematic review and meta-analysis.

AIMS: There are conflicting data as to the impact of procedural volume on outcomes with specific reference to the incidence of major complications after catheter ablation for atrial fibrillation. Questions regarding minimum volume requirements and whether these should be per centre or per operator remain unclear. Studies have reported divergent results. We performed a systematic review and meta-analysis of studies reporting the relationship between either operator or hospital atrial fibrillation (AF) ablation volumes and incidence of complications. METHODS AND RESULTS: Databases were searched for studies describing the relationship between operator or hospital AF ablation volumes and incidence of complications which were published prior to 12 June 2020. Of 1593 articles identified, 14 (315 120 patients) were included in the meta-analysis. Almost two-thirds of the procedures were performed in low-volume centres. Both hospital volume of ≥50 and ≥100 procedures/year were associated with a significantly lower incidence of complications compared to <50/year (4.2% vs. 5.5%, OR = 0.58, 95% CI 0.50-0.66, P < 0.001) or <100/year (5.5% vs. 6.2%, OR = 0.62, 95% CI 0.53-0.73, P < 0.001), respectively. Hospitals performing ≥50 procedures/year demonstrated significantly lower mortality compared with those performing <50 procedures/year (0.16% vs. 0.55%, OR = 0.33, 95% CI 0.26-0.43, P < 0.001). A similar relationship existed between proceduralist volume of <50/year and incidence of complications [3.75% vs. 12.73%, P < 0.001; OR = 0.27 (0.23-0.32)]. CONCLUSION: There is an inverse relationship between both hospital and proceduralist AF ablation volume and the incidence of complications. Implementation of minimum hospital and operator AF ablation volume standards should be considered in the context of a broader strategy to identify AF ablation Centers of Excellence.

Acute kidney injury after MitraClip implantation in patients with severe mitral regurgitation.

INTRODUCTION: Percutaneous mitral valve repair (PMVR), such as MitraClip, is performed on high-risk patients and involves hemodynamic alternations that may cause acute kidney injury (AKI). We aimed to evaluate the incidence of AKI, predictors for developing AKI and the correlation with mortality after MitraClip. METHODS: We performed a retrospective analysis of collected data from patients who underwent PMVR in two tertiary medical centers in Israel to identify factors associated with AKI. RESULTS: The study population included 163 patients. The median age was 77 years; 60.7% of patients were male. The median eGFR significantly decreased post-procedure from 49 (35-72) to 47.8 (31-65.5) ml/min/1.73 m2 (p < .001). Forty-seven patients (29%) developed AKI. None of the patients who developed AKI required hemodialysis. Predictors of AKI included: baseline eGFR ≤30 ml/min/1.73 m2 , severity of residual MR, TMPG>5 mmHg, diuretic use, and re-do procedures. Among the patients who developed AKI there was an improvement in kidney function during follow-up, and creatinine levels significantly decreased from a peak mean creatinine of 179.5 (143-252) mmol/l to 136 (92-174) mmol/l (p < .001). However, 19% (9 out of 47) of patients experienced partial recovery and their creatinine level, when compared to their baseline, remained elevated. One-year survival showed a trend for increased mortality among patients who developed AKI (86.2% vs. 80.9%, p = .4), and patients who developed AKI that persisted had increased 1-year mortality compared with patients that had recovered their kidney function (86.8% vs. 55.6%, p = .01). CONCLUSION: The incidence of AKI after MitraClip is high. AKI is reversible in most patients; however, the persistence of kidney injury is associated with increased 1-year mortality.

Pulmonary artery pressures and outcomes after MitraClip.

AIMS: We evaluated the impact of MitraClip on systolic pulmonary artery pressure (sPAP) and the effects of baseline sPAP on outcomes. METHODS AND RESULTS: In a cohort of patients who underwent MitraClip implantation, three groups were defined according to pre-procedure sPAP levels. Clinical and echocardiographic data were compared. The study included 177 patients: 59 had severe pulmonary hypertension (PHT), 96 had mild to moderate PHT, and 22 had no PHT. In patients with pre-existing severe PHT, sPAP was reduced from 70.8 ± 9.2 to 56.8 ± 13.7 mmHg (P < 0.001), sPAP remained unchanged in patients with mild to moderate PHT but was significantly increased from 30.8 ± 4.3 to 38.6 ± 8.3 mmHg in the no-PHT group (P < 0.001). Improvement of sPAP was observed in 77% of severe PHT group, while worsening of sPAP was more common among patients with no-PHT [57% compared with 33% among the mild to moderate PHT and 7% in the severe PHT group, respectively, (P < 0.001)]. One year survival was similar among the study groups. CONCLUSIONS: MitraClip decreases PHT among patients with severe PHT. A concerning finding is that most patients with no-PHT increase their sPAP.

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.

For Whom the Bell Tolls : Refining Risk Assessment for Sudden Cardiac Death.

Sudden cardiac death is one of the most important causes of death worldwide. Advancements in medical treatment, percutaneous interventions, and device therapy (ICD and CRTD) showed consistent reduction in mortality, mainly in survivors of SCD and in patients with ischemic cardiomyopathy and depressed left ventricular function. Patients with non-ischemic cardiomyopathies, mildly reduced LV function, and channelopathies have increased risk for SCD. Identifying the subgroup of these patients before they experience life-threatening or fatal events is essential to further improve outcomes. In this review, we aimed to summarize the current knowledge for risk stratification and primary prevention, to describe the gaps in evidence, and to discuss future directions for screening and treating patients at risk for SCD. PURPOSE OF REVIEW: The purpose of this review is to provide a comprehensive description of the etiologies of sudden cardiac death, risk stratification strategies, and to describe the current medical and interventional therapies. We aimed to discuss the current gaps in our knowledge of primary prevention of SCD and to review novel approaches and interventions. RECENT FINDINGS: The incidence of SCD has decreased in the last two decades due to improved pharmacological treatment and ICD implantation in SCD survivors and in patients with reduced left ventricular function and ischemic cardiomyopathy. The efficacy of ICD in patients with non-ischemic cardiomyopathy is challenged by new findings from the DANISH trial. Catheter ablation is new emerging strategy to prevent SCD in patients with scar relater or PVC-triggered ventricular arrhythmias. Despite the new treatments, SCD is still a major burden. ICD remains the cornerstone for patients with ischemic cardiomyopathy, whereas appropriate risk stratification of the patients with non-ischemic cardiomyopathy and channelopathies is needed to further improve outcomes. The future of ablation as the treatment and prevention of SCD remains to be studied.

MitraClip Technique Five Years after Alfieri Stitch Mitral Valve Repair.

The case is described of a successful MitraClip procedure performed on an 88-year-old patient with severe mitral regurgitation (MR), five years after she had undergone mitral valve repair using the Alfieri surgical procedure. It is suggested that the MitraClip procedure is an option in patients with severe MR persisting after the Alfieri procedure. Video 1: Transesophageal echocardiography before the MitraClip procedure. Severe mitral regurgitation with preserved left ventricular systolic function. The main regurgitant jet originates from the medial commissure. Video 2: Transesophageal echocardiography: clip placement and jet reduction. A single clip placement on the medial portion of the mitral valve, resulting in elimination of the medial jet and reduction of the overall mitral regurgitant jet from grade 4+ to grade 2+.