Correlation of Extent of Left Ventricular Endocardial Unipolar Low Voltage Zones with Ventricular Tachycardia in Non-ischemic Cardiomyopathy

BACKGROUND

Endocardial electrogram (EGM) characteristics in non-ischemic cardiomyopathy (NICM) have not been explored adequately for prognostication.

OBJECTIVES

We aim to study correlation of bipolar and unipolar EGM characteristics with left ventricular ejection fraction (LVEF) and ventricular tachycardia (VT) in NICM.

METHODS

Electroanatomical mapping of LV was performed. Correlation of EGM characteristics with LVEF was performed. Differences between groups with and without VT and predictors of VT were studied.

RESULTS

In 43 patients, unipolar EGM variables had better correlation with baseline LVEF than bipolar EGM variables: unipolar voltage (r=+0.36), peak negative unipolar voltage (r=-0.42), peak positive unipolar voltage (r=+0.38), and percentage area of unipolar LVZ (r=-0.41). Global mean unipolar voltage (HR- 0.4; 95% C.I 0.2-0.8), extent of unipolar LVZ (HR- 1.6; 95% CI 1.1-2.3) and % area of unipolar LVZ (HR- 1.6; 95% CI 1.1-2.3) were significant predictors of VT. For classification of patients with VT, extent of unipolar LVZ had AUC of 0.82 (95% CI 0.69-0.95; p<0.001), and % area of unipolar LVZ had AUC of 0.83 (95% CI 0.71-0.96; p=0.01). Cut-off of >3 segments for extent of unipolar LVZ had the best diagnostic accuracies (sensitivity- 90%; specificity- 67%) and cut-off of 33% for percentage area of unipolar LVZ had the best diagnostic accuracy (sensitivity- 95%; specificity- 60%) for VT.

CONCLUSION

In NICM, extent and percentage area of unipolar low voltage zones are significant predictors of VT. Cut-offs of >3 segments of unipolar LVZ and >33% area of unipolar LVZ, have good diagnostic accuracies for association with VT.

Programmed Ventricular Stimulation: Risk Stratification and Guiding Antiarrhythmic Therapies

Electrophysiologic testing with programmed ventricular stimulation (PVS) has been utilized to induce ventricular tachycardia (VT), thereby improving risk stratification for patients with ischemic and nonischemic cardiomyopathies and determining the effectiveness of antiarrhythmic therapies, especially catheter ablation. A variety of procedural aspects can be modified during PVS in order to alter the sensitivity and specificity of the test including the addition of multiple baseline pacing cycle lengths, extrastimuli, and pacing locations. The definition of a positive result is also critically important, which has varied from exclusively sustained monomorphic VT (>30 seconds) to any ventricular arrhythmia regardless of morphology. In this review, we discuss the history of PVS and evaluate its role in sudden cardiac death risk stratification in a variety of patient populations. We propose an approach to future investigations that will capitalize on the unique ability to vary the sensitivity and specificity of this test. We then discuss the application of PVS during and following catheter ablation. The strategies that have been utilized to improve the efficacy of intraprocedural PVS are highlighted during a discussion of the limitations of this probabilistic strategy. The role of noninvasive programmed stimulation is also reviewed in predicting recurrent VT and informing management decisions including repeat ablations, modifications in antiarrhythmic drugs, and implantable cardioverter-defibrillator programming. Based on the available evidence and guidelines, we propose an approach to future investigations that will allow clinicians to optimize the use of PVS for risk stratification and assessment of therapeutic efficacy.

Accuracy of symptoms and pulse checking for detecting atrial fibrillation following catheter ablation

BACKGROUND

There is growing interest in the possibility of discontinuing oral anticoagulation following successful catheter ablation of atrial fibrillation (AF). However, it remains unknown whether patients can accurately detect arrhythmia recurrences following ablation. We therefore sought to characterize the accuracy of pulse checking and arrhythmia symptoms for the identification of AF following ablation.

METHODS

This prospective cohort study included patients at the Hospital of the University of Pennsylvania with an insertable cardiac monitor (ICM) treated with catheter ablation for AF who recorded the results from minimum twice daily pulse checks and additionally with arrhythmia symptoms into a diary for 2 months following their procedure. Accuracy of this self-assessment protocol was determined by comparison to ICM-detected AF.

RESULTS

A total of 55 patients (age 69 ± 8 years, 30 (55%) male, CHA2DS2VASc score 3.2 ± 1. 5) were included. Patients recorded a total of 5911 pulse checks, and there were 280 episodes of ICM-documented AF among 26 patients with an average duration of 2.5 ± 3.3 h. Among 362 episodes of patient-suspected AF, 134 correlated with ICM-identified AF (37% true positive rate). Of the 5549 pulse checks that did not identify AF, 196 correlated with ICM-identified AF (4% false negative rate). Twice daily pulse checking had a sensitivity of 47% and a specificity of 96% for identifying each episode of AF.

CONCLUSIONS

Our data indicate that a strategy of pulse checks and symptom assessment is insufficient to identify all episodes of AF in many patients following catheter ablation.

Substrate and arrhythmia characterization using the multi-electrode Optrell mapping catheter for ventricular arrhythmia ablation-a single-center experience

BACKGROUND

The use of a multi-electrode Optrell mapping catheter during ventricular tachycardia (VT) or premature ventricular complex (PVC) ablation procedures has not been widely reported.

OBJECTIVES

We aim to describe the feasibility and safety of using the Optrell multipolar mapping catheter (MPMC) to guide catheter ablation of VT and PVCs.

METHODS

We conducted a single-center, retrospective evaluation of patients who underwent VT or PVC ablation between June and November 2022 utilizing the MPMC.

RESULTS

A total of 20 patients met the inclusion criteria (13 VT and 7 PVC ablations, 80% male, 61 ± 15 years). High-density mapping was performed in the VT procedures with median 2753 points [IQR 1471-17,024] collected in the endocardium and 12,830 points [IQR 2319-30,010] in the epicardium. Operators noted challenges in manipulation of the MPMC in trabeculated endocardial regions or near valve apparatus. Late potentials (LPs) were detected in 11 cases, 7 of which had evidence of isochronal crowding demonstrated during late annotation mapping. Two patients who also underwent entrainment mapping had critical circuitry confirmed in regions of isochronal crowding. In the PVC group, high-density voltage and activation mapping was performed with a median 1058 points [IQR 534-3582] collected in the endocardium.

CONCLUSIONS

This novel MPMC can be used safely and effectively to create high-density maps in LV endocardium or epicardium. Limitations of the catheter include a longer wait time for matrix formation prior to starting point collection and challenges in manipulation in certain regions.

Predictors of nonpulmonary vein triggers for atrial fibrillation: A clinical risk score

BACKGROUND

Targeting nonpulmonary vein triggers (NPVTs) after pulmonary vein isolation may reduce atrial fibrillation (AF) recurrence. Isoproterenol infusion and cardioversion of spontaneous or induced AF can provoke NPVTs but typically require vasopressor support and increased procedural time.

OBJECTIVE

The purpose of this study was to identify risk factors for the presence of NPVTs and create a risk score to identify higher-risk subgroups.

METHODS

Using the AF ablation registry at the Hospital of the University of Pennsylvania, we included consecutive patients who underwent AF ablation between January 2021 and December 2022. We excluded patients who did not receive NPVT provocation testing after failing to demonstrate spontaneous NPVTs. NPVTs were defined as nonpulmonary vein ectopic beats triggering AF or focal atrial tachycardia. We used risk factors associated with NPVTs with P <.1 in multivariable logistic regression model to create a risk score in a randomly split derivation set (80%) and tested its predictive accuracy in the validation set (20%).

RESULTS

In 1530 AF ablations included, NPVTs were observed in 235 (15.4%). In the derivation set, female sex (odds ratio [OR] 1.40; 95% confidence interval [CI] 0.96-2.03; P = .080), sinus node dysfunction (OR 1.67; 95% CI 0.98-2.87; P = .060), previous AF ablation (OR 2.50; 95% CI 1.70-3.65; P <.001), and left atrial scar (OR 2.90; 95% CI 1.94-4.36; P <.001) were risk factors associated with NPVTs. The risk score created from these risk factors (PRE2SSS2 score; [PRE]vious ablation: 2 points, female [S]ex: 1 point, [S]inus node dysfunction: 1 point, left atrial [S]car: 2 points) had good predictive accuracy in the validation cohort (area under the receiver operating characteristic curve 0.728; 95% CI 0.648-0.807).

CONCLUSION

A risk score incorporating predictors for NPVTs may allow provocation of triggers to be performed in patients with greatest expected yield.

One-year outcomes after stereotactic body radiotherapy for refractory ventricular tachycardia

BACKGROUND

Cardiac stereotactic body radiotherapy (SBRT) has emerged as a promising noninvasive treatment for refractory ventricular tachycardia (VT).

OBJECTIVE

The purpose of this study was to describe the safety and effectiveness of SBRT for VT in refractory to extensive ablation.

METHODS

After maximal medical and ablation therapy, patients were enrolled in a prospective registry. Available electrophysiological and imaging data were integrated to generate a plan target volume. All SBRTs were planned with a single 25 Gy fraction using respiratory motion mitigation strategies. Clinical outcomes at 6 weeks, 6 months, and 12 months were analyzed and compared with the 6 months prior to treatment. VT burden (implantable cardioverter-defibrillator [ICD] shocks and antitachycardia pacing sequences) as well as clinical and safety outcomes were the main outcomes.

RESULTS

Fifteen patients were enrolled and underwent planning. Fourteen (93%) underwent treatment, with 12 (80%) surviving to the end of the 6-week period and 10 (67%) surviving to 12 months. From 6 week to 12 months, there was recurrence of VT, which resulted in either appropriate antitachycardia pacing or ICD shocks in 33% (4 of 12). There were significant reductions in treated VT at 6 weeks to 6 months (98%) and at 12 months (99%) compared to the 6 months before treatment. There was a nonsignificant trend toward lower amiodarone dose at 12 months. Four deaths occurred after treatment, with no changes in ventricular function.

CONCLUSION

For a select group of high-risk patients with VT refractory to standard therapy, SBRT is associated with a reduction in VT and appropriate ICD therapies over 1 year.

Evaluation of organized atrial arrhythmias after cryptogenic stroke

Background

Long-term rhythm monitoring to detect atrial fibrillation (AF) following a cryptogenic stroke (CS) is well established. However, the burden of organized atrial arrhythmias in this population is not well defined.

Objective

The purpose of this study was to assess the incidence and risk factors for organized atrial arrhythmias in patients with CS.

Methods

We evaluated all patients with CS who received an insertable cardiac monitor (ICM) between October 2014 and April 2020. All ICM transmissions categorized as AF, tachycardia, or bradycardia were reviewed. We evaluated the time to detection of organized AF and the combination of either organized atrial arrhythmia or AF.

Results

A total of 195 CS patients with ICMs were included (51% men; mean age 66 ± 12 years; mean CHA2DS2-VASC score 4.6). Over mean follow-up of 18.9 ± 11.2 months, organized atrial arrhythmias lasting ≥30 seconds were detected in 45 patients (23%), of whom 62% did not have AF. Seventeen patients had both organized atrial arrhythmia and AF, and another 21 patients had AF only. Compared to those with normal left atrial size, patients with left atrial enlargement had a higher adjusted risk for development of atrial arrhythmias (mild left atrial enlargement: hazard ratio 1.99; 95% confidence interval 1.06-3.75; moderate/severe left atrial enlargement: hazard ratio 3.06; 95% confidence interval 1.58-5.92).

Conclusion

Organized atrial arrhythmias lasting ≥30 seconds are detected in nearly one-fourth of CS patients. Two-thirds of these patients did not have AF. Further studies are required to evaluate the impact of organized atrial arrhythmias on recurrent stroke risk.

Intraoperative ultrasound-guided pectoral nerve blocks for cardiac implantable device procedures

BACKGROUND

Pectoral nerve (PECs) blocks are established regional anesthesia techniques that can provide analgesia to the anterior chest wall. Although commonly performed preoperatively by anesthesiologists, the feasibility of electrophysiologist-performed PECs blocks from within cardiac implantable electronic device (CIED) pockets at the time of implantation has not been established. The objective of this study is to assess the feasibility of routine PECs blocks performed by the electrophysiologist from within the exposed device pocket at the time of CIED procedures.

METHODS

Patients undergoing CIED procedures underwent a PECs I block (15 cc of 1% lidocaine/0.25% bupivacaine) injected between the pectoralis major and minor muscles guided by ultrasound placed in the device pocket, or PECs II block, which included a second injection (15 cc) between pectoralis minor and serratus anterior muscles. Postoperatively, pain was assessed on a numeric scale (0-10) at 1, 2, 4, and 24 h, and 2 weeks after the procedure.

RESULTS

Among 20 patients (age 65 ± 16 years, 70% male, 55% with history of chronic pain), PECs I (75%) and PECs II (25%) blocks were performed. The procedures were de novo implantation (n = 17) or device revision (n = 3). The average pain score in the first 4 h was 0.4 ± 0.8 and 0.3 ± 0.6 at 24 h after the procedure. During the 24-h postoperative period, 4 patients received opioids. Two patients were discharged with opioids for pain unrelated to the procedure.

CONCLUSIONS

Intraoperative PECs blocks can be feasibly performed from within an exposed pocket at the time of CIED procedures with minimal postoperative pain.

Utility of Very High-Output Pacing to Identify VT Circuits in Patients Manifesting Traditionally Inexcitable Scar

BACKGROUND

Entrainment and pace mapping are used to identify critical components (CCs) of ventricular tachycardia (VT) circuits. In patients with dense myocardial scarring, VT circuits may elude capture at standard high pacing outputs (up to 10 mA at a 2-millisecond pulse width).

OBJECTIVES

The purpose of this study was to assess the utility of very high-output pacing (V-HOP, 50 mA at 2 milliseconds) for identifying CCs of VT circuits after standard high pacing output failed to elicit capture in densely scarred myocardial tissue.

METHODS

Our standard VT ablation approach included electroanatomic mapping for substrate characterization and entrainment and/or pace mapping to identify CCs of VT circuits. Patients that required V-HOP to capture sites of interest comprised the study cohort. Ablation endpoints were VT termination and noninducibility.

RESULTS

Twenty-five patients (71 ± 10 years of age, all males) undergoing 26 VT ablations met the inclusion criteria. The mean left ventricular ejection fraction was 30% ± 14%, and 85% had ischemic cardiomyopathy. V-HOP was used to successfully entrain VT in 17 patients, yielding central isthmus sites in 10 and entrance/exit sites in 4. VT terminated with radiofrequency ablation at these sites in 15 patients. In 9 patients, V-HOP identified scar locations with a delayed exit. Acute procedural success was achieved in 24 patients without any adverse events. Over a follow-up period of 16 ± 21 months, 2 patients experienced VT recurrence requiring repeat ablation during which the same location was targeted successfully in 1 patient.

CONCLUSIONS

In VT patients with a dense scar that is traditionally inexcitable, V-HOP can identify CCs of the re-entrant circuit and guide successful ablation.

Identifying Origin of Nonpulmonary Vein Triggers Using 2 Stationary Linear Decapolar Catheters: A Novel Algorithm

BACKGROUND

Targeting nonpulmonary vein triggers (NPVTs) of atrial fibrillation (AF) after pulmonary vein isolation can be challenging. NPVTs are often single ectopic beats with a surface P-wave obscured by a QRS or T-wave.

OBJECTIVES

The goal of this study was to construct an algorithm to regionalize the site of origin of NPVTs using only intracardiac bipolar electrograms from 2 linear decapolar catheters positioned in the posterolateral right atrium (along the crista terminalis with the distal bipole pair in the superior vena cava) and in the proximal coronary sinus (CS).

METHODS

After pulmonary vein isolation in 42 patients with AF, pacing from 15 typical anatomic NPVT sites was conducted. For each pacing site, the electrogram activation sequence was analyzed from the CS catheter (simultaneous/chevron/inverse chevron/distal-proximal/proximal-distal) and activation time (ie, CSCTAT) between the earliest electrograms from the 2 decapolar catheters was measured referencing the earliest CS electrogram; a negative CSCTAT value indicates the crista terminalis catheter electrogram was earlier, and a positive CSCTAT value indicates the CS catheter electrogram was earlier. A regionalization algorithm with high predictive value was defined and tested in a validation cohort with AF NPVTs localized with electroanatomic mapping.

RESULTS

In the study patient cohort (71% male; 43% with persistent AF, 52% with left atrial dilation), the algorithm grouped with high precision (positive predictive value 81%-99%, specificity 94%-100%, and sensitivity 30%-94%) the 15 distinct pacing sites into 9 clinically useful regions. Algorithm testing in a 98 patient validation cohort showed predictive accuracy of 91%.

CONCLUSIONS

An algorithm defined by the activation sequence and timing of electrograms from 2 linear multipolar catheters provided accurate regionalization of AF NPVTs to guide focused detailed mapping.

Presence of sinus rhythm at time of ablation in patients with persistent atrial fibrillation undergoing pulmonary vein isolation is associated with improved long-term arrhythmia outcomes

BACKGROUND

Adverse structural and electrical remodeling underlie persistent atrial fibrillation (PersAF). Restoration of sinus rhythm (SR) prior to ablation in PersAF may improve the underlying substrate, thus improving arrhythmia outcomes. The aim of this study was to evaluate if the presence of SR at time of ablation is associated with improved long-term arrhythmia outcomes of a limited catheter ablation (CA) strategy in PersAF.

METHODS

Patients with PersAF undergoing pulmonary vein isolation at our institution from 2014-2018 were included. We compared patients who presented for ablation in SR (by cardioversion and/or antiarrhythmic drugs [AADs]) to those who presented in AF. Primary outcome of interest was freedom from atrial arrhythmias (AAs) on or off AADs at 1 year after single ablation. Secondary outcomes included freedom from AAs on or off AADs overall, freedom from AAs off AADs at 1 year, and time to recurrent AF.

RESULTS

Five hundred seventeen patients were included (322 presented in AF, 195 SR). The primary outcome was higher in those who presented for CA in SR as compared to AF (85.6% vs. 77.0%, p = 0.017). Freedom from AAs off AAD at 12 months was also higher in those presenting in SR (59.0% vs. 44.4%; p = 0.001) and time to recurrent AF was longer (p = 0.008). Presence of SR at CA was independently associated with the primary outcome at 12 months (OR 1.77; 95% CI 1.08-2.90) and overall (OR 1.89; 95% CI 1.26-2.82).

CONCLUSIONS

Presence of SR at time of ablation is associated with improved long-term arrhythmia outcomes of limited CA in PersAF.

Septal Substrate Ablation Guided by Delayed Transmural Conduction Times: A Novel Ablation Approach to Target Intramural Substrates

BACKGROUND

Intraprocedural identification of intramural septal substrate for ventricular tachycardia (ISS-VT) in nonischemic cardiomyopathy (NICM) is challenging. Delayed (>40 ms) transmural conduction time (DCT) with right ventricular basal septal pacing has been previously shown to identify ISS-VT.

OBJECTIVES

This study sought to determine whether substrate catheter ablation incorporating areas of DCT may improve acute and long-term outcomes.

METHODS

We included patients with NICM and ISS-VT referred for catheter ablation between 2016 and 2020. ISS-VT was defined by the following: 1) confluent septal areas of low unipolar voltage (<8.3 mV) in the presence of normal or minimal bipolar abnormalities; and 2) presence of abnormal electrograms in the septum. Substrate ablation was guided by the following: 1) activation and/or entrainment mapping for tolerated VT and pace mapping with ablation of abnormal septal electrograms for unmappable VTs (n = 57, Group 1); and 2) empirically extended to target areas of DCT during right ventricular basal septal pacing regardless of their participation in inducible VT(s) but sparing the conduction system when possible (n = 24, Group 2).

RESULTS

There were no significant baseline differences between Groups 1 and 2. Noninducibility of any VT programmed stimulation at the end of ablation was higher in Group 2 compared with Group 1 (80% vs 53%; P = 0.03). At 12-month follow-up, single-procedure VT-free survival was significantly higher (79% vs 46%; P = 0.006) and the time to VT recurrence was longer (mean 10 ± 3 months vs 7 ± 4 months; P = 0.02) in Group 2 compared with Group 1.

CONCLUSIONS

In patients with NICM and ISS-VT, a substrate ablation strategy that incorporates areas of DCT appears to improve freedom from recurrent VT.

Impact of Median Sternotomy on Safety and Efficacy of the Subcutaneous Implantable Cardioverter Defibrillator

BACKGROUND

Subcutaneous implantable cardioverter defibrillators (S-ICDs) are an attractive alternative to transvenous ICDs among those not requiring pacing. However, the risks of damage to the S-ICD electrode during sternotomy and adverse interactions with sternal wires remain unclear. We sought to determine the rates of damage to the S-ICD lead during sternotomy, inappropriate shocks from electrical noise due to interaction with sternal wires, and failure to terminate spontaneous or induced ventricular arrhythmias.

METHODS

Retrospective, multicenter study of patients undergoing sternotomy before or after S-ICD implantation. Clinical, procedural, and device-related data were collected by each center and analyzed by the coordinating center. These data were compared with a historical control cohort of nonsternotomy patients.

RESULTS

Of 196 identified patients (52±16 years, 47 women), 166 underwent S-ICD implantation after sternotomy and 30 sternotomy after S-ICD. There was no damage to any lead among those who underwent sternotomy after S-ICD. Defibrillation threshold testing was performed in 63% at implant, with 91% first shock success. During a median follow-up of 29 months (range, 1-188), S-ICD first shocks successfully terminated spontaneous ventricular arrhythmias in 31 of 32 patients (97%). Inappropriate shocks occurred in 22 patients, most commonly related to T wave oversensing (n=14). Compared with the nonsternotomy controls, there were no differences in rates of first shock success for induced or spontaneous arrhythmias or rate of inappropriate shocks.

CONCLUSIONS

Sternotomy before or after S-ICD does not confer additional risk relative to a historical control group without sternotomy.

Pacing-Induced Cardiomyopathy

Right ventricular (RV) pacing-induced cardiomyopathy (PICM) is typically defined as left ventricular systolic dysfunction resulting from electrical and mechanical dyssynchrony caused by RV pacing. RV PICM is common, occurring in 10-20% of individuals exposed to frequent RV pacing. Multiple risk factors for PICM have been identified, including male sex, wider native and paced QRS durations, and higher RV pacing percentage, but the ability to predict which individuals will develop PICM remains modest. Biventricular and conduction system pacing, which better preserve electrical and mechanical synchrony, typically prevent the development of PICM and reverse left ventricular systolic dysfunction after PICM has occurred.

Sinus Rhythm Electrocardiographic Abnormalities, Sites of Origin, and Ablation Outcomes of Ventricular Premature Depolarizations Initiating Ventricular Fibrillation

BACKGROUND

Ventricular fibrillation (VF) can be initiated by ventricular premature depolarizations (VPDs) in the absence of obvious structural abnormalities.

OBJECTIVE

To determine the prevalence of 12-lead ECG sinus rhythm reduced QRS amplitude, QRS fractionation (QRSf) and early repolarization (ER) pattern, and the outcome of catheter ablation and VPD anatomic distribution in patients with VPDs initiating VF.

METHODS

We compared a cohort with no apparent structural heart disease and VPDs initiating VF (Group 1, n=42) to a reference cohort (Group 2, n=61) of patients with no structural heart disease and symptomatic unifocal VPDs.

RESULTS

A reduced QRS amplitude (<.55 mV) in aVF (59 % vs 10%, p<0.001), QRSf in ≥2 contiguous leads (50% vs 16%, p<0.001) and early repolarization pattern (21.4% vs 1.6%, p=0.01) were more common in Group 1 vs Group 2. At least one abnormal ECG finding was present in 34 (81%) Group 1 vs 17 (28%) Group 2 patients, (p<0.001). VPD origin included RV and LV distal Purkinje system and moderator band/ papillary muscles, in 83% Group 1 vs 18% Group 2 patients, p<0.001. VF was eliminated with single ablation procedure in 77% of Group 1 patients with at least 2 years of follow-up.

CONCLUSIONS

A reduced QRS amplitude (<.55 mV) in aVF, QRS fractionation in ≥2 contiguous leads and/or an early repolarization pattern are frequently observed in patients with VPDs initiating VF. VPDs initiating VF typically originate from the distal Purkinje system and papillary muscles and can be successfully eliminated with catheter ablation.

Multicenter experience with andexanet alfa for refractory pericardial bleeding during catheter ablation of atrial fibrillation

INTRODUCTION

Pericardial bleeding is a rare but life-threatening complication of atrial fibrillation (AF) ablation. Patients taking uninterrupted oral anticoagulation (AC) may be at increased risk for refractory bleeding despite pericardiocentesis and administration of protamine. In such cases, andexanet alfa can be given to reverse rivaroxaban or apixaban. In this study, we aim to describe the rate of acute hemostasis and thromboembolic complications with andexanet for refractory pericardial bleeding during AF ablation.

METHODS AND RESULTS

In this multicenter, case series, participating centers identified patients who received a dose of apixaban or rivaroxaban within 24 h of AF ablation, developed refractory pericardial bleeding during the procedure despite pericardiocentesis and administration of protamine and received andexanet. Eleven patients met inclusion criteria, with mean age of 73.5 ± 5.3 years and median CHA₂ DS₂ -VASc score 4 [3-5]. All patients received protamine and pericardiocentesis, and 9 (82%) received blood products. All patients received a bolus of andexanet followed, in all but one, by a 2-h infusion. Acute hemostasis was achieved in eight patients (73%) while three required emergent surgery. One patient (9%) experienced acute ST-elevation myocardial infarction after receiving andexanet. Therapeutic AC was restarted after a mean of 2.2 ± 1.9 days and oral AC was restarted after a mean of 2.9 ± 1.6 days, with no recurrent bleeding.

CONCLUSION

In patients on uninterrupted apixaban or rivaroxaban, who develop refractory pericardial bleeding during AF ablation, andexanet can achieve hemostasis thereby avoiding the need for emergent surgery. However, there is a risk of thromboembolism following administration.

Neuromodulation for the Treatment of Refractory Ventricular Arrhythmias

BACKGROUND

Neuromodulation is increasingly recognized as a therapeutic strategy for patients with refractory ventricular arrhythmias (VAs). Percutaneous stellate ganglion blockade (SGB), transcutaneous magnetic stimulation (TcMS), and surgical cardiac sympathetic denervation (CSD) have all been utilized in this setting.

OBJECTIVES

This study sought to characterize contemporary use and outcomes of these neuromodulation techniques for patients with refractory VA.

METHODS

This retrospective cohort study included all patients at the Hospital of the University of Pennsylvania with antiarrhythmic drug (AAD)-refractory VA from 2019 to 2021 who were treated with SGB, TcMS, or CSD.

RESULTS

A total of 34 patients (age 61 ± 14 years, 15 polymorphic VAs [44%], refractory to 1.8 ± 0.8 AADs) met inclusion criteria. SGB was performed on 11 patients (32%), TcMS on 19 (56%), and CSD on 7 (21%). Neuromodulation was associated with a reduction in the number of episodes of sustained VAs from 7 [IQR: 4-12] episodes in the 24 hours before the initial neuromodulation strategy to 0 [IQR: 0-1] episodes in the subsequent 24 hours (P < 0.001). During 1.2 ± 1.1 years of follow-up, 21 (62%) experienced recurrent VAs, and among those patients, the median time to recurrence was 3 [IQR: 1-25] days. Outcomes were similar among patients with monomorphic and polymorphic VAs. Among patients who had an acute myocardial infarction within 30 days before neuromodulation, the burden of VAs decreased from 11 [IQR: 7-12] episodes to 0 episodes in the 24 hours after treatment.

CONCLUSIONS

Autonomic neuromodulation with SGB, TcMS, or CSD in patients with AAD-refractory VAs is safe and results in substantial acute reduction of VA although recurrent arrhythmias are common, and not all patients experience a reduction in arrhythmia burden.

Safety and efficacy of catheter ablation for ventricular tachycardia in elderly patients with structural heart disease: a systematic review and meta-analysis

PURPOSE

Data regarding the age-specific outcomes of VT ablation in patients with structural heart disease (SHD) are scarce. We performed a systematic review and meta-analysis to evaluate the outcomes of VT ablation in elderly vs. younger patients with SHD.

METHODS

MEDLINE/PubMed, Cochrane, and Google Scholar and references comparing VT ablation in elderly vs. younger patients were screened and studies included if matching inclusion and exclusion criteria.

RESULTS

Five retrospective studies enrolling 2778 SHD patients (868 elderly vs. 1910 younger) were included. Compared to younger subjects, the elderly showed similar results in terms of acute ablation success (OR 0.78, 95% CI 0.54-1.13, p = 0.189) and minor complications (OR 1.74, 95% CI 0.74-4.09, p = 0.205), a trend toward a higher risk of major complications (OR 2.30, 95% CI 0.83-6.40, p = 0.110) and significantly higher rates of all complications (OR 2.67, 95% CI 1.51-4.71, p = 0.001) and periprocedural mortality (OR 1.93, 95% CI 1.24-3.01, p = 0.004). At a mean follow-up of 18 months, elderly patients showed similar long-term VT recurrence rate (OR 1.02, 95% CI 0.85-1.22, p = 0.861) and higher all-cause mortality (OR 2.00, 95% CI 1.40-2.86, p < 0.001). In elderly patients, urgent VT ablation is associated with higher risk of major complications (beta = 0.06, p < 0.001) and periprocedural mortality (beta = 0.03, p = 0.029), while advanced age is associated with higher risk of major complications (beta = 0.29 with p = 0.009) and all complications + periprocedural mortality (beta = 0.17 with p = 0.037).

CONCLUSIONS

Compared to younger patients, VT ablation in elderly showed similar results in terms of acute ablation success and long-term VT recurrence rate with a significantly higher risk of all complications, periprocedural mortality, and long-term mortality, especially when the procedure is performed urgently and in the most aged patients. Large prospective multicenter randomized trials are required to confirm these findings.

Safety of Pill-in-the-Pocket Class 1C Antiarrhythmic Drugs for Atrial Fibrillation

BACKGROUND

Guidelines recommend that initial trial of a "pill-in-the-pocket" (PIP) Class 1C antiarrhythmic drug (AAD) for cardioversion of atrial fibrillation (AF) be performed in a monitored setting because of the potential for adverse reactions.

OBJECTIVES

This study sought to characterize real-world, contemporary use of the PIP approach, including the setting of initiation and incidence of adverse events.

METHODS

This retrospective cohort study included all patients at the Hospital of the University of Pennsylvania treated with a PIP approach for AF between 2007 and 2020.

RESULTS

A total of 273 patients (age 56 ± 13 years; 182 [67%] male; CHA₂DS₂VASc score 1.1 ± 1.2) took a first dose of PIP AAD. Flecainide was used in 151 (55%) and propafenone in 122 (45%). The first dose of PIP AAD was taken in a monitored setting in 167 (62%). Significant adverse events occurred in 7 patients (3%), 2 of whom had taken the dose in a monitored setting. Significant adverse events included unexplained syncope (1 of 7), symptomatic bradycardia/hypotension (4 of 7), and 1:1 atrial flutter (2 of 7). All occurred in patients taking 300 mg of flecainide (n = 4) or 600 mg of propafenone (n = 3). Electrical cardioversion was performed in 29 (11%) patients because of failure of the AAD to terminate AF. One patient required intravenous fluids and vasopressors for 2 hours because of persistent hypotension and bradycardia. Two patients required permanent pacemakers for bradycardia. The remaining patients required no intervention.

CONCLUSIONS

Our data support the current recommendation to initiate PIP AAD in a monitored setting because of rare significant adverse reactions that can require urgent intervention.

Impact of Left Ventricular Papillary Muscle Ventricular Arrhythmia Ablation on Mitral Valve Function

BACKGROUND

Although efficacious, catheter ablation (CA) of ventricular arrhythmias (VAs) originating from left ventricular (LV) papillary muscles (PAPs) has the potential to affect mitral valve (MV) function.

OBJECTIVES

The aim of this study was to determine whether lesions delivered during CA of VAs from LV PAPs affected MV function.

METHODS

Consecutive patients undergoing CA of LV PAP VAs from January 2015 to December 2020 in whom both preprocedural and postprocedural transthoracic echocardiography was performed were included. Radiofrequency ablation was performed with an irrigated-tip catheter with or without contact force sensing and intracardiac echocardiographic guidance. The PAPs were delineated into segments: tip, body, and base. Pre- and post-CA transthoracic echocardiograms were reviewed to assess MV regurgitation, which was graded 0 (none), 1 (mild), 2 (moderate), or 3 (severe). A change of ≥2 grades from baseline was considered significant.

RESULTS

A total of 103 patients (mean age 63 ± 15 years, 78% men) were included. VAs were ablated from the anterolateral PAP in 35% (n = 36), posteromedial PAP in 55% (n = 57), and both PAPs in 10% (n = 10). Lesion distribution was as follows: PAP tip in 52 (50%), PAP base in 34 (33%), PAP body in 13 (13%), and entire PAP in 4 (4%). The mean number of lesions delivered was 16 ± 13 (median 14). Of 103 patients, 102 (99%) showed no change in MV function.

CONCLUSIONS

Using intracardiac echocardiographic guidance, lesions can be safely delivered on various aspects of this structure without adverse impact on MV function.

Advances in Cardiac Electrophysiology

Despite the global COVID-19 pandemic, during the past 2 years, there have been numerous advances in our understanding of arrhythmia mechanisms and diagnosis and in new therapies. We increased our understanding of risk factors and mechanisms of atrial arrhythmias, the prediction of atrial arrhythmias, response to treatment, and outcomes using machine learning and artificial intelligence. There have been new technologies and techniques for atrial fibrillation ablation, including pulsed field ablation. There have been new randomized trials in atrial fibrillation ablation, giving insight about rhythm control, and long-term outcomes. There have been advances in our understanding of treatment of inherited disorders such as catecholaminergic polymorphic ventricular tachycardia. We have gained new insights into the recurrence of ventricular arrhythmias in the setting of various conditions such as myocarditis and inherited cardiomyopathic disorders. Novel computational approaches may help predict occurrence of ventricular arrhythmias and localize arrhythmias to guide ablation. There are further advances in our understanding of noninvasive radiotherapy. We have increased our understanding of the role of His bundle pacing and left bundle branch area pacing to maintain synchronous ventricular activation. There have also been significant advances in the defibrillators, cardiac resynchronization therapy, remote monitoring, and infection prevention. There have been advances in our understanding of the pathways and mechanisms involved in atrial and ventricular arrhythmogenesis.

Extra-cardiac BCAA catabolism lowers blood pressure and protects from heart failure

Pharmacologic activation of branched-chain amino acid (BCAA) catabolism is protective in models of heart failure (HF). How protection occurs remains unclear, although a causative block in cardiac BCAA oxidation is widely assumed. Here, we use in vivo isotope infusions to show that cardiac BCAA oxidation in fact increases, rather than decreases, in HF. Moreover, cardiac-specific activation of BCAA oxidation does not protect from HF even though systemic activation does. Lowering plasma and cardiac BCAAs also fails to confer significant protection, suggesting alternative mechanisms of protection. Surprisingly, activation of BCAA catabolism lowers blood pressure (BP), a known cardioprotective mechanism. BP lowering occurred independently of nitric oxide and reflected vascular resistance to adrenergic constriction. Mendelian randomization studies revealed that elevated plasma BCAAs portend higher BP in humans. Together, these data indicate that BCAA oxidation lowers vascular resistance, perhaps in part explaining cardioprotection in HF that is not mediated directly in cardiomyocytes.

Catheter Ablation for Atrial Fibrillation in Adult Congenital Heart Disease: An International Multicenter Registry Study

BACKGROUND

Data on atrial fibrillation (AF) ablation and outcomes are limited in patients with congenital heart disease (CHD). We aimed to investigate the characteristics of patients with CHD presenting for AF ablation and their outcomes.

METHODS

A multicenter, retrospective analysis was performed of patients with CHD undergoing AF ablation between 2004 and 2020 at 13 participating centers. The severity of CHD was classified using 2014 PACES/HRS guidelines. Clinical data were collected. One-year complete procedural success was defined as freedom from atrial tachycardia or AF in the absence of antiarrhythmic drugs or including previously failed antiarrhythmic drugs (partial success).

RESULTS

Of 240 patients, 127 (53.4%) had persistent AF, 62.5% were male, and mean age was 55.2±0.9 years. CHD complexity categories included 147 (61.3%) simple, 69 (28.8%) intermediate, and 25 (10.4%) severe. The most common CHD type was atrial septal defect (n=78). More complex CHD conditions included transposition of the great arteries (n=14), anomalous pulmonary veins (n=13), tetralogy of Fallot (n=8), cor triatriatum (n=7), single ventricle physiology (n=2), among others. The majority (71.3%) of patients had trialed at least one antiarrhythmic drug. Forty-six patients (22.1%) had reduced systemic ventricular ejection fraction <50%, and mean left atrial diameter was 44.1±0.7 mm. Pulmonary vein isolation was performed in 227 patients (94.6%); additional ablation included left atrial linear ablations (25.4%), complex fractionated atrial electrogram (19.2%), and cavotricuspid isthmus ablation (40.8%). One-year complete and partial success rates were 45.0% and 20.5%, respectively, with no significant difference in the rate of complete success between complexity groups. Overall, 38 patients (15.8%) required more than one ablation procedure. There were 3 (1.3%) major and 13 (5.4%) minor procedural complications.

CONCLUSIONS

AF ablation in CHD was safe and resulted in AF control in a majority of patients, regardless of complexity. Future work should address the most appropriate ablation targets in this challenging population.

Impact of atrial fibrillation recurrences during the blanking period following catheter ablation on long-term arrhythmia-free survival: a prospective study with continuous monitoring

BACKGROUND

The significance of atrial fibrillation (AF) recurrences during the 90-day blanking period following catheter ablation is controversial. Studies to date examining the impact of AF recurrences during the blanking period have been limited by intermittent monitoring. We sought to test whether AF recurrences during the blanking period are associated with long-term recurrences using continuous monitoring.

METHODS

Patients undergoing AF ablation by a single operator at an academic medical center between 2015 and 2019, who either already had a cardiac implantable electronic device (CIED) with an atrial lead or received an insertable cardiac monitor (ICM), were followed for long-term AF recurrence. Recurrence was defined as > 30 s by CIED and > 2 min by ICM. All device-reported AF episodes were adjudicated by a physician.

RESULTS

Of 196 consecutive patients, 51 (26%) had AF recurrence in the blanking period and 145 (74%) did not. Over the year following ablation, those who had an AF recurrence in the blanking period were significantly more likely to have long-term AF recurrences than those without AF in the blanking period (log rank p < 0.001). The higher the burden of AF recurrences during the blanking period, the more likely AF was to recur long-term (hazard ratio 1.04 [CI 1.01-1.06] per 1% increase in burden, p = 0.002).

CONCLUSION

Using continuous monitoring of a sizable population, we confirmed that AF recurrences in the blanking period following ablation are in fact associated with long-term AF recurrences. The higher the burden of recurrence, the more likely AF is to recur long-term.

Subcutaneous Implantable Cardioverter-defibrillator Explantation-A Single Tertiary Center Experience

The subcutaneous implantable cardioverter-defibrillator (S-ICD) is an appealing alternative to transvenous ICD systems. However, data on indications for S-ICD explantations are sparse. The objective of this study was to assess the incidence and indications for S-ICD explantation at a large tertiary referral center. We conducted a retrospective study of all S-ICD explantations performed from 2014–2020. Data on demographics, comorbidities, implantation characteristics, and indications for explantation were collected. A total of 64 patients underwent S-ICD explantation during the study period. During that time, there were 410 S-ICD implantations at our institution, of which 53 (12.9%) were explanted with a mean duration from implant to explant of 19.7 ± 20.1 months. The mean age of the patients at explantation was 44.8 ± 15.3 years, and 42% (n = 27) were women. The indication for S-ICD implantation was primary prevention in 58% and secondary prevention in 42% of patients, respectively. The most common reason for explantation was infection (32.8%), followed by abnormal sensing (25%) and the need for pacing (18.8%). Those who underwent S-ICD explantation for pacing indications were significantly older (55.7 ± 13.6 vs. 42.3 ± 14.6 years, P = 0.005) with a wider QRS duration (111 ± 19 vs. 98 ± 19 ms, P = 0.03) at device implantation compared to patients who underwent explantation for other indications. The incidence of S-ICD explantation in a large tertiary practice was 12.9%. While infection was the indication for one-third of the explantations, a significant number of explantations were due to sensing abnormalities and the need for pacing. These data may have implications for patient selection for S-ICD implantation.

Utility of Prolonged Duration Endocardial Ablation for Ventricular Arrhythmias Originating From the Left Ventricular Summit

OBJECTIVES

This study sought to explore whether prolonged duration (PD) radiofrequency ablation (RFA) from adjacent endocardial locations can improve catheter ablation (CA) outcomes of left ventricular summit (LVS) ventricular arrhythmias (Vas).

BACKGROUND

CA of VAs originating from the LVS region can be challenging.

METHODS

Patients undergoing CA of LVS VAs from January 1, 2015, to December 31, 2019, were included. Standard RFA approach involved incremental power titration (20-45 W) over 60-120 seconds with irrigated tip catheter to achieve 10%-12% impedance drop. Prolonged duration RFA involved similar power titration; however, lesion application was extended beyond 120 seconds (maximum 5 minutes). Lesions were confined to lowest aspect of aortic cusps and/or subvalvular LV outflow tract region (≤0.5 cm from the valve). Procedural success was defined as suppression of VA ≥30 minutes postablation and clinical success as no arrhythmia symptoms on follow-up and >80% reduction of VA burden on postprocedure monitor.

RESULTS

This study included 102 patients (60±14 years old, 62% male): standard RFA in 80 and PD RFA in 38. Procedural success was achieved in 54 patients with standard and 32 patients with PD RFA (68% vs 84%; P = 0.05). Short-term clinical success was achieved in 48 patients (60%) with standard and 30 patients (79%) with PD RFA (P = 0.04). Two pericardial effusions occurred (1 in each group) and no steam pops were noted. Patients in whom standard RFA was successful were more likely to have R/S ratio >1 or absence of qS in lead I (odds ratio: 3.35; 95% CI: 1.20-9.35; P = 0.03).

CONCLUSIONS

Prolonged duration RFA from adjacent endocardial locations is a safe and effective technique for successfully targeting challenging LVS VAs that fail standard RFA.

Effect of Transcutaneous Magnetic Stimulation in Patients With Ventricular Tachycardia Storm: A Randomized Clinical Trial

IMPORTANCE

Autonomic neuromodulation provides therapeutic benefit in ventricular tachycardia (VT) storm. Transcutaneous magnetic stimulation (TcMS) can noninvasively and nondestructively modulate a patient's nervous system activity and may reduce VT burden in patients with VT storm.

OBJECTIVE

To evaluate the safety and efficacy of TcMS of the left stellate ganglion for patients with VT storm.

DESIGN, SETTING, AND PARTICIPANTS

This double-blind, sham-controlled randomized clinical trial took place at a single tertiary referral center between August 2019 and July 2021. The study included 26 adult patients with 3 or more episodes of VT in 24 hours.

INTERVENTIONS

Patients were randomly assigned to receive a single session of either TcMS that targeted the left stellate ganglion (n = 14) or sham stimulation (n = 12).

MAIN OUTCOMES AND MEASURES

The primary outcome was freedom from VT in the 24-hour period following randomization. Key secondary outcomes included safety of TcMS on cardiac implantable electronic devices, as well as burden of VT in the 72-hour period following randomization.

RESULTS

Among 26 patients (mean [SD] age, 64 [13] years; 20 [77%] male), a mean (SD) of 12.7 (10.3) episodes of VT occurred within the 24 hours preceding randomization. Patients had recurrent VT despite taking a mean (SD) of 2.0 (0.6) antiarrhythmic drugs (AADs), and 11 patients (42%) required mechanical hemodynamic support at the time of randomization. In the 24-hour period after randomization, VT recurred in 4 of 14 patients (29% [SD 47%]) in the TcMS group vs 7 of 12 patients (58% [SD 51%]) in the sham group (P = .20). In the 72-hour period after randomization, patients in the TcMS group had a mean (SD) of 4.5 (7.2) episodes of VT vs 10.7 (13.8) in the sham group (incidence rate ratio, 0.42; P < .001). Patients in the TcMS group were taking fewer AADs 24 hours after randomization compared with baseline (mean [SD], 0.9 [0.8] vs 1.8 [0.4]; P = .001), whereas there was no difference in the number of AADs taken for the sham group (mean [SD], 2.3 [0.8] vs 1.9 [0.5]; P = .20). None of the 7 patients in the TcMS group with a cardiac implantable electronic device had clinically significant effects on device function.

CONCLUSIONS AND RELEVANCE

In this randomized clinical trial, findings support the potential for TcMS to safely reduce the burden of VT in the setting of VT storm in patients with and without cardiac implantable electronic devices and inform the design of future trials to further investigate this novel treatment approach.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04043312.

Longitudinal Electrocardiographic Assessment in the Brugada Syndrome

Background

The type 1 electrocardiographic (ECG) pattern diagnostic of Brugada syndrome (BrS) can be dynamic. Limited studies have rigorously evaluated the temporal stability of the Brugada ECG pattern.

Objective

We sought to evaluate fluctuations of the Brugada pattern in serial resting ECGs from BrS patients managed within a large health care system.

Methods

In our cohort of BrS patients with at least 2 standard, resting ECGs recorded on separate clinical encounters, we evaluated serial changes in the Brugada pattern and categorized patients into 1 of 3 groups: dynamic was defined as the presence of both type 1 and non–type 1 patterns in available ECGs; the provoked-only group was defined as having a non–type 1 Brugada pattern across resting ECGs; and the persistent group was defined as having a type 1 pattern on all ECGs. We also evaluated the clinical risk in this cohort according to the Shanghai risk score.

Results

In 72 patients with BrS (mean age 46 ± 15 years, 69% male), 828 standard, resting ECGs were recorded over a median duration of 30.2 (interquartile range 6.3–68.1) months. The dynamic group comprised 50 (69% of the cohort) patients, the provoked-only group consisted of 17 patients (24% of the cohort), and the persistent group included 5 patients. No significant differences were detected in the total number of ECGs evaluated during the follow-up period between any of the groups. Only sinus node dysfunction and a prior cardiac arrest were associated with the persistent type 1 group. The majority of patients had a low annualized risk of lethal arrhythmic events.

Conclusion

Most BrS patients have a dynamic Brugada pattern noted on longitudinal, resting ECGs. Expert consensus statements should provide clarity on the frequency of obtaining resting ECGs in patients suspected of having BrS during follow-up.

Substrate Characterization and Outcome of Catheter Ablation of Ventricular Tachycardia in Patients With Nonischemic Cardiomyopathy and Isolated Epicardial Scar

BACKGROUND

The substrate for ventricular tachycardia (VT) in left ventricular (LV) nonischemic cardiomyopathy may be epicardial. We assessed the prevalence, location, endocardial electrograms, and VT ablation outcomes in LV nonischemic cardiomyopathy with isolated epicardial substrate.

METHODS

Forty-seven of 531 (9%) patients with LV nonischemic cardiomyopathy and VT demonstrated normal endocardial (>1.5 mV)/abnormal epicardial bipolar low-voltage area (LVA, <1.0 mV and signal abnormality). Abnormal endocardial unipolar LVA (≤8.3 mV) and endocardial bipolar split electrograms and predictors of ablation success were assessed.

RESULTS

Epicardial bipolar LVA (27.3 cm² [interquartile range, 15.8-50.0]) localized to basal (40), mid (8), and apical (3) LV with basal inferolateral LV most common (28/47, 60%). Of 44 endocardial maps available, 40 (91%) had endocardial unipolar LVA (24.5 cm² [interquartile range, 9.4-68.5]) and 29 (67%) had characteristic normal amplitude endocardial split electrograms opposite the epicardial LVA. At mean of 34 months, the VT-free survival was 55% after one and 72% after multiple procedures. Greater endocardial unipolar LVA than epicardial bipolar LVA (hazard ratio, 10.66 [CI, 2.63-43.12], P=0.001) and number of inducible VTs (hazard ratio, 1.96 [CI, 1.27-3.00], P=0.002) were associated with VT recurrence.

CONCLUSIONS

In patients with LV nonischemic cardiomyopathy and VT, the substrate may be confined to epicardial and commonly basal inferolateral. LV endocardial unipolar LVA and normal amplitude bipolar split electrograms identify epicardial LVA. Ablation targeting epicardial VT and substrate achieves good long-term VT-free survival. Greater endocardial unipolar than epicardial bipolar LVA and more inducible VTs predict VT recurrence.