Cryoballoon Ablation as Initial Therapy for Atrial Fibrillation.

BACKGROUND: In patients with symptomatic paroxysmal atrial fibrillation that has not responded to medication, catheter ablation is more effective than antiarrhythmic drug therapy for maintaining sinus rhythm. However, the safety and efficacy of cryoballoon ablation as initial first-line therapy have not been established. METHODS: We performed a multicenter trial in which patients 18 to 80 years of age who had paroxysmal atrial fibrillation for which they had not previously received rhythm-control therapy were randomly assigned (1:1) to receive treatment with antiarrhythmic drugs (class I or III agents) or pulmonary vein isolation with a cryoballoon. Arrhythmia monitoring included 12-lead electrocardiography conducted at baseline and at 1, 3, 6, and 12 months; patient-activated telephone monitoring conducted weekly and when symptoms were present during months 3 through 12; and 24-hour ambulatory monitoring conducted at 6 and 12 months. The primary efficacy end point was treatment success (defined as freedom from initial failure of the procedure or atrial arrhythmia recurrence after a 90-day blanking period to allow recovery from the procedure or drug dose adjustment, evaluated in a Kaplan-Meier analysis). The primary safety end point was assessed in the ablation group only and was a composite of several procedure-related and cryoballoon system-related serious adverse events. RESULTS: Of the 203 participants who underwent randomization and received treatment, 104 underwent ablation, and 99 initially received drug therapy. In the ablation group, initial success of the procedure was achieved in 97% of patients. The Kaplan-Meier estimate of the percentage of patients with treatment success at 12 months was 74.6% (95% confidence interval [CI], 65.0 to 82.0) in the ablation group and 45.0% (95% CI, 34.6 to 54.7) in the drug-therapy group (P<0.001 by log-rank test). Two primary safety end-point events occurred in the ablation group (Kaplan-Meier estimate of the percentage of patients with an event within 12 months, 1.9%; 95% CI, 0.5 to 7.5). CONCLUSIONS: Cryoballoon ablation as initial therapy was superior to drug therapy for the prevention of atrial arrhythmia recurrence in patients with paroxysmal atrial fibrillation. Serious procedure-related adverse events were uncommon. (Supported by Medtronic; STOP AF First ClinicalTrials.gov number, NCT03118518.).

Conduction system pacing: overview, definitions, and nomenclature.

Pacing from the right ventricle is associated with an increased risk of development of congestive heart failure, increases in total and cardiac mortality, and a worsened quality of life. Conduction system pacing has become increasingly realized as an alternative to right ventricular apical pacing. Conduction system pacing from the His bundle and left bundle branch area has been shown to provide physiologic activation of the ventricle and may be an alternative to coronary sinus pacing. Conduction system pacing has been studied as an alternative for both bradycardia pacing and for heart failure pacing. In this review, we summarize the clinical results of conduction system pacing under a variety of different clinical settings. The anatomic targets of conduction system pacing are illustrated, and electrocardiographic correlates of pacing from different sites in the conduction system are defined. Ultimately, clinical trials comparing conduction system pacing with standard right ventricular apical pacing and cardiac resynchronization therapy pacing will help define its benefit and risks compared with existing techniques.

Safety and feasibility of conduction system pacing in patients with congenital heart disease.

INTRODUCTION: Conduction system pacing (CSP) has emerged as an ideal physiologic pacing strategy for patients with permanent pacing indications. We sought to evaluate the safety and feasibility of CSP in a consecutive series of unselected patients with congenital heart disease (CHD). METHODS: Consecutive patients with CHD in which CSP was attempted were included. Safety and feasibility, implant tools and electrical parameters at implant and at follow-up were evaluated. RESULTS: A total of 20 patients were included (10 with a previous device). A total of 10 patients had complex forms of CHD, 9 moderate defects and 1 a simple defect. CSP was achieved in 75% of cases (10 His bundle pacing, 5 left bundle branch pacing) with left ventricular septal pacing in the remaining 5 patients. Procedure times and fluoroscopy times were prolongued (126 ± 82 min and 27 ± 30 min, respectively). Ventricular lead implant times widely varied ranging from 4 to 115 min, (mean 31 ± 28 min) and the use of multiple delivery sheaths was frequent (50%). The QRS width was reduced from 145 ± 36 ms at baseline to 116 ± 18 ms with CSP. Implant electrical parameters included: CSP pacing threshold 0.95 ± 0.65 V; R wave amplitude 9.2 ± 8.8 mV and pacing impedance 632 ± 183 Ohms, and remained stable at a median follow-up of 478 days (interquartile range: 225-567). Systemic ventricle systolic function and NYHA class (1.50 ± 0.51 vs. 1.10 ± 0.31; p = .008) significantly improved at follow-up. Lead revision was required in one patient at Day 4. CONCLUSIONS: Permanent CSP is safe and feasible in patients with CHD although implant technique is complex.

Development of an international standard set of outcome measures for patients with atrial fibrillation: a report of the International Consortium for Health Outcomes Measurement (ICHOM) atrial fibrillation working group.

AIMS: As health systems around the world increasingly look to measure and improve the value of care that they provide to patients, being able to measure the outcomes that matter most to patients is vital. To support the shift towards value-based health care in atrial fibrillation (AF), the International Consortium for Health Outcomes Measurement (ICHOM) assembled an international Working Group (WG) of 30 volunteers, including health professionals and patient representatives to develop a standardized minimum set of outcomes for benchmarking care delivery in clinical settings. METHODS AND RESULTS: Using an online-modified Delphi process, outcomes important to patients and health professionals were selected and categorized into (i) long-term consequences of disease outcomes, (ii) complications of treatment outcomes, and (iii) patient-reported outcomes. The WG identified demographic and clinical variables for use as case-mix risk adjusters. These included baseline demographics, comorbidities, cognitive function, date of diagnosis, disease duration, medications prescribed and AF procedures, as well as smoking, body mass index (BMI), alcohol intake, and physical activity. Where appropriate, and for ease of implementation, standardization of outcomes and case-mix variables was achieved using ICD codes. The standard set underwent an open review process in which over 80% of patients surveyed agreed with the outcomes captured by the standard set. CONCLUSION: Implementation of these consensus recommendations could help institutions to monitor, compare and improve the quality and delivery of chronic AF care. Their consistent definition and collection, using ICD codes where applicable, could also broaden the implementation of more patient-centric clinical outcomes research in AF.

His-bundle pacing: A novel treatment for left bundle branch block-mediated cardiomyopathy.

BACKGROUND: Chronic left bundle branch block (LBBB) can lead to LBBB-mediated cardiomyopathy from left ventricular dysynchrony. His-bundle pacing (HBP) results in direct electrical synchrony using the native His-Purkinje system, providing a novel treatment for this cardiomyopathy. OBJECTIVE: To assess the feasibility of HBP for cardiac resynchronization therapy (CRT) in LBBB-mediated cardiomyopathy patients. METHODS: Retrospective database review was conducted on patients who underwent CRT by the HBP capable provider at Indiana University Health and Eskenazi Hospital from August 2015 to August 2017. A subset of patients who met the predefined syndrome criteria of LBBB-mediated cardiomyopathy who underwent HBP were identified. Clinical, echocardiographic, and electrocardiographic variables were extracted at baseline and follow-up. RESULTS: Nine patients had cardiomyopathy and LBBB. Among those two were lost to follow-up. Seven patients were included in the analysis. The average time from device implantation to the last follow-up was 14.5 months. Left ventricular ejection fraction improved on average from 25% to 50% (p = .0001). The left ventricular end-systolic dimension decreased from 47 to 37 mm (p = .003) and the left ventricular end-diastolic dimension decreased from 55 to 48 mm (p = .03). QRS duration with HBP-CRT decreased from 152 to 115 ms. New York Heart Association classification improved from an average of 2.7-2. CONCLUSION: HBP is a viable technique for pursuing CRT in patients with LBBB-mediated cardiomyopathy.

Long term performance and safety of His bundle pacing: A multicenter experience.

INTRODUCTION: Several single-center short-term studies have demonstrated the feasibility, safety, and positive clinical outcomes of permanent His bundle pacing (HBP). We performed a retrospective study to evaluate long-term technical and safety performances of HBP in a large population of pacemaker patients from two different centers. METHODS AND RESULTS: The analysis includes 844 patients (345 female, mean age = 75 ± 9 years) who underwent successful permanent HBP for pacemaker indications from 2004 to 2016. The main endpoints were long term electrical performances including pacing threshold, sensing, impedance, and freedom from pacing related complications. The pacing indication was AV Block in 348 (41.2%) patients, sinus node disease in 147 (17.4%), any bradycardia indication in patients with atrial fibrillation in 335 (39.7%) patients and need for cardiac resynchronization therapy in 14 (1.7%) patients. Mean pacing capture thresholds and sensed R waves were 1.6 V and 5.8 mV, respectively at implant and 2.0 V and 6.1 mV at chronic follow-up. During the median follow up of 3 years (interquartile range = 1-6 years), HBP was free of any complication in 91.6% of patients. In the first 368 patients, HBP was achieved using a deflectable curve delivery system, while in 476 using the fixed curve sheath. A significant difference was found in the thresholds (2.4 ± 1.0 V and 1.7 ± 1.1 V, P < .001, respectively) and complications (11.9% and 4.2%, P < .001, respectively) between the two groups. CONCLUSIONS: Permanent HBP was safe and effective during long-term follow-up. The fixed curved delivery sheath offered significantly better electrical parameters and reliability over time. The results of this multicenter study are consistent with recent studies.

His Bundle Pacing in Heart Failure-Concept and Current Data.

PURPOSE OF REVIEW: His bundle pacing (HBP) has continued to emerge as a viable alternative to both right ventricular pacing (RVP) and cardiac resynchronization therapy. In recent years, a considerable amount of research has been published with regard to using HBP to treat congestive heart failure (CHF) and this article presents a concise yet comprehensive review of this literature. RECENT FINDINGS: Studies have demonstrated that HBP is useful for CHF patients who are non-responders to biventricular pacing (BiVP) or have a history of previously failed coronary sinus lead placement, right/left bundle branch block cardiomyopathy, or pacing-induced cardiomyopathy. Additionally, HBP is useful in patients with an indication for pacing who are expected to have a RVP burden exceeding 20%. The theoretical benefit of utilizing the native His Purkinje system to excite cardiac tissue is appealing as it can result in true cardiac resynchronization. Limited studies have shown its benefit in reducing heart failure symptoms and improving cardiac function. Larger randomized clinical trials and further investments into developing better technologies are highly desired to make its clinical use sustainable in the long run.

Permanent His-bundle pacing: a systematic literature review and meta-analysis.

Aims: Permanent cardiac pacing of the His-bundle restores and retains normal electrical activation of the ventricles. Data on His-bundle pacing (HBP) are largely limited to small single-centre reports, and clinical benefits and risks have not been systematically examined. We sought to systematically examine published studies of patients undergoing permanent HBP and quantify the benefits and risks of the therapy. Methods and results: PubMed, Embase, and Cochrane Library were searched for full-text articles on permanent HBP. Clinical outcomes of interest included implant success rate, procedural and lead complications, pacing thresholds, QRS duration, and ejection fraction at follow-up, and mortality. Data were extracted and summarized. Where possible, meta-analysis of aggregate data was performed. Out of 2876 articles, 26 met the inclusion criteria representing 1438 patients with an implant attempt. Average age of patients was 73 years and 62.1% were implanted due to atrioventricular block. Overall average implant success rate was 84.8% and was higher with use of catheter-delivered systems (92.1%; P < 0.001). Average pacing thresholds were 1.71 V at implant and 1.79 V at >3 months follow-up; although, pulse widths varied at testing. Average left ventricular ejection fractions (LVEFs) were 42.8% at baseline and 49.5% at follow-up. There were 43 complications observed in 907 patients across the 17 studies that reported safety information. Conclusion: Among 26 articles of permanent HBP, the implant success rate averaged 84.8% and LVEF improved by an average of 5.9% during follow-up. Specific reporting of our clinical outcomes of interest varied widely, highlighting the need for uniform reporting in future HBP trials.

Permanent His bundle pacing: Electrophysiological and echocardiographic observations from long-term follow-up.

BACKGROUND: Permanent His bundle pacing (HBP) is a physiological alternative to right ventricular pacing. It is not known whether HBP can cause His-Purkinje conduction (HPC) disease. The aim of our study is to assess His bundle capture and its effect on left ventricular (LV) function in long-term follow-up and to determine HPC at the time of pulse generator change (GC) in patients with chronic HBP. METHODS: HB electrograms were recorded from the pacing lead at implant and GC. HBP QRS duration (QRSd), His-ventricular (HV) intervals, and HB pacing thresholds at GC were compared with implant measurements. HPC was assessed by pacing at cycle lengths of 700 ms, 600 ms, and 500 ms at GC. LV internal diameters, ejection fraction (EF), and valve dysfunction at baseline were compared with echocardiography during follow-up. RESULTS: GC was performed in 20 patients (men 13; age 74 ± 14 years) with HBP at 70 ± 24 months postimplant. HV intervals remained unchanged from initial implant (44 ± 4 ms vs 45 ± 4 ms). During HBP at 700 ms, 600 ms, and 500 ms (n = 17), consistent 1:1 HPC was present. HBP QRSd remained unchanged during follow-up (117 ± 20 ms vs 118 ± 23 ms). HBP threshold at implant and GC was 1.9 ± 1.1 V and 2.5 ± 1.2 V @ 0.5 ms. Despite high pacing burden (77 ± 13%), there was no significant change in LVEF (50 ± 14% at implant) during follow-up (55 ± 6%, P = 0.06). CONCLUSIONS: HBP does not appear to cause new HPC abnormalities and is associated with stable HBP QRSd during long-term follow-up. Despite high pacing burden, HBP did not result in deterioration of left ventricular systolic function or cause new valve dysfunction.

Permanent nonselective His bundle pacing in an adult with L-transposition of the great arteries and complete AV block.

We report the placement of a permanent transvenous nonselective His bundle pacing lead in conjunction with a transvenous pacemaker/implantable cardioverter-defibrillator in an adult with Levo-Transposition of the Great Arteries (L-TGA) and a stenotic coronary sinus (CS) ostium, which would not accommodate a transvenous left ventricular (LV) pacing lead. Nonselective His bundle pacing provided a nearly identical ventricular activation pattern in this previously unpaced patient. Many L-TGA patients will have an eventual need for permanent pacing and, given the challenges of CS cannulation, His bundle pacing may represent a preferred modality rather than pure morphologic LV pacing or surgical systemic ventricular lead placement to achieve optimal electrical synchrony.

Healthcare Utilization and Quality of Life Improvement after Ablation for Paroxysmal AF in Younger and Older Patients.

BACKGROUND: Atrial fibrillation (AF) prevalence increases significantly with age. Little is known about the effect of AF ablation on quality of life and healthcare utilization in the elderly. The objective of this study was to quantify the healthcare utilization and quality of life benefits of catheter ablation for AF, for patients ≥65 years compared to patients <65 years. METHODS: Two multicenter U.S. registry studies enrolled patients with paroxysmal AF. Baseline characteristics and acute outcomes were collected for 736 patients receiving catheter ablation with the Navistar® ThermoCool® SF Catheter (Biosense Webster, Inc., Diamond Bar, CA, USA). Healthcare utilization and quality of life outcomes were collected through 1 year postablation for 508 patients. RESULTS: The rates of acute pulmonary vein isolation were high and similar between patients ≥65 years and <65 years (97.5% vs 95.8%, P = 0.2130). Length of stay for the index procedure was similar between age groups with 82.2% of the older group and 83.2% of the younger group having one-day hospitalization. Disease-specific quality of life instrument scores improved significantly and similarly for older and younger patients at 1 year postablation, compared to baseline. AF-related hospitalizations and emergency department visits were similar or lower in older patients compared to younger patients, as reported at 1 year postablation. CONCLUSION: For older patients undergoing catheter ablation for paroxysmal AF, healthcare utilization parameters were lower or not significantly different than for younger patients, and quality of life outcomes were similarly improved. These findings support the use of catheter ablation as a treatment option in older patients with paroxysmal AF.

History of His bundle pacing.

Chronic right ventricular (RV) pacing has been shown over the years to exert detrimental physiological changes including increased risk for heart failure and atrial fibrillation. His bundle pacing offers the promise of physiological activation of the ventricular tissue, with the potential for reducing the detrimental effects of RV pacing. We describe His bundle pacing in a historical context and briefly highlight several clinical trials that have helped shape the landscape of permanent His bundle pacing.

Trials and Tribulations of Ventricular Pacing.

In this review, we describe the current evidence for permanent ventricular pacing and the unmet needs related to chronic cardiac pacing.

How to Perform Permanent His Bundle Pacing: Tips and Tricks.

Right ventricular pacing can cause ventricular dyssynchrony and result in reduced left ventricular systolic function and heart failure. Permanent His bundle pacing is a more physiologic form of pacing, but can be technically challenging. In this article, we describe our technique for permanent His bundle pacing including special considerations and limitations associated with His bundle pacing.

Permanent His-Bundle Pacing: Case Studies.

His bundle pacing (HBP) is a physiological alternative to right ventricular pacing. In addition to patients with normal His-Purkinje conduction, HBP can be valuable in patients with infranodal atrioventricular (AV) block and patients undergoing AV node ablation. The following case studies illustrate the challenges associated with HBP.

The Complexity of the His Bundle: Understanding Its Anatomy and Physiology through the Lens of the Past and the Present.

In this paper, we describe the anatomy and physiology of the His bundle and describe the mechanisms by which permanent His-bundle pacing can be accomplished.

Anatomical approach to permanent His bundle pacing: Optimizing His bundle capture.

Permanent His bundle pacing is a physiological alternative to right ventricular pacing. In this article we describe our approach to His bundle pacing in patients with AV nodal and intra-Hisian conduction disease. It is essential for the implanters to understand the anatomic variations of the His bundle course and its effect on the type of His bundle pacing achieved. We describe several case examples to illustrate our anatomical approach to permanent His bundle pacing in this article.

Electrophysiological observations of acute His bundle injury during permanent His bundle pacing.

BACKGROUND: Permanent His bundle pacing (HBP) is a physiological alternative to right ventricular pacing (RVP). Catheter manipulation during HBP can cause trauma to the His bundle during implantation. We sought to determine acute and long-term incidence of His bundle (HB) injury with HBP. METHODS: Patients undergoing permanent HBP at Geisinger Wyoming Valley Medical Center from 2006 to 2014 formed the study group. Patients with pre-existing His-Purkinje disease (HPD) were excluded from the study. Any development of new bundle branch block (BBB) or AV block (B) during acute HBP lead-induced block was recorded. Resolution of AVB and/or BBB was documented. RESULTS: HBP was attempted in 450 patients. In 358 patients without HPD, 28 (7.8%) developed acute HB injury in the form of complete AVB (4, 1.1%), RBBB (21, 5.9%) or LBBB (3, 0.8%) during HBP lead placement. In all 7 patients with AVB or LBBB, conduction completely recovered. The HB electrogram from the lead displayed injury current in all 7 patients. Lead-induced RBBB resolved in 12 of 21 patients and persisted in 9 (2.5%) patients. Pacing from the HBP lead resulted in correction of acute conduction block in 27 of 28 patients and 8 of 9 patients with chronic RBBB. None of the patients with transient conduction block developed new conduction disease during follow-up of 21±19months. CONCLUSIONS: Despite acute trauma to HB in 7.8% of patients undergoing permanent HBP, complete resolution of conduction block occurred in 19 of 28 patients (68%). RBBB persisted in 9 patients (32%) but mostly normalized with HBP.

Acute His-Bundle Injury Current during Permanent His-Bundle Pacing Predicts Excellent Pacing Outcomes.

INTRODUCTION: His-bundle (HB) pacing (P) is a physiological alternative to right ventricular pacing (RVP), but is technically challenging and limited by higher pacing thresholds. Myocardial injury current (IC) recorded during right ventricular lead placement implies good tissue contact and is associated with low-pacing thresholds. IC at the HB has not been previously described. We hypothesized that HBIC during permanent HBP may be associated with lower pacing thresholds. METHODS: Permanent HBP was performed using Medtronic Select Secure(tm) (Medtronic Inc., Minneapolis, MN, USA) delivered via a fixed-curve (C315 His) sheath. HB electrogram (EGM) was recorded in a unipolar fashion from the lead tip. Presence or absence of HBIC was documented. HBP threshold, sensing, and impedances were recorded at implant, 2 weeks, 2 months, and 1 year. RESULTS: Sixty patients (age 72 ± 15 years; male 55%, sick sinus syndrome 40%, atrioventricular block 60%, fluoroscopy duration 9.2 ± 3.7 minutes) underwent successful permanent HBP. HBIC was recorded in 22 (37%) patients (group I). HBEGM without IC was recorded in the remaining 38 (63%) patients (group II). Pacing threshold at implant, 2 weeks, 2 months, and 1 year were significantly lower in group I (1.16 ± 0.4 V; 1.18 ± 0.5 V; 1.23 ± 0.6 V; 1.3 ± 0.6 V @ 0.5 ms) compared to group II (1.75 ± 0.7 V; 1.82 ± 0.8 V; 1.93 ± 0.8 V; 1.98 ± 0.9 V @ 0.5 ms, P < 0.05), respectively. CONCLUSIONS: IC can be recorded at the HB during permanent HBP in 37% of patients. HBIC is associated with significantly lower pacing thresholds compared to patients in whom HBIC was not recorded. HBIC may be a marker for superior short-term HBP thresholds.

Acute safety of an open-irrigated ablation catheter with 56-hole porous tip for radiofrequency ablation of paroxysmal atrial fibrillation: analysis from 2 observational registry studies.

INTRODUCTION: This report presents safety data on the use of a new open-irrigation radiofrequency ablation (RFA) catheter with a 56-hole porous tip in 742 patients enrolled in 2 US prospective, multicenter observational registry studies representing real-world use of the catheter. METHODS: This analysis is comprised of patients who underwent RFA of drug-refractory recurrent symptomatic paroxysmal atrial fibrillation (AF). Acute adverse events (AEs) were collected and categorized by seriousness, timing, and relatedness, with 7 days of follow-up data in one study and at least 120 days of data from a 1-year follow-up in the other. Acute serious adverse events (SAEs) that were identified as potentially related to the device and/or procedure were adjudicated by an independent safety committee. RESULTS: A total of 30 patients (4.0%) in the combined studies experienced an acute SAE related to the device and/or procedure, which was similar in the subset of patients age 65 and over (4.2%). These SAEs included 1.2% cardiac tamponade/perforation, 0.7% pericarditis, 0.5% pulmonary events, and 0.8% vascular access complications. No myocardial infarction, stroke, transient ischemic attack, or atrioesophageal fistulas within 7 days postprocedure were reported. In the study with extended follow-up, 1 pulmonary vein stenosis and 1 esophageal injury were seen beyond 7 days postprocedure (0.2% each). There were no device or procedure related deaths. CONCLUSION: Results from 2 large observational studies demonstrated that a new porous tip RFA catheter was safe for the treatment of drug refractory, recurrent, symptomatic paroxysmal AF, including treatment of older patients (≥65 years).