Rates of pulmonary vein reconnection at repeat ablation for recurrent atrial fibrillation and its impact on outcomes among females and males.

BACKGROUND: Several studies have demonstrated that females have a higher risk of arrhythmia recurrence after pulmonary vein (PV) isolation for atrial fibrillation (AF). There are limited data on sex-based differences in PV reconnection rates at repeat ablation. We aimed to investigate sex-based differences in electrophysiological findings and atrial arrhythmia recurrence after repeat AF ablation METHODS: We conducted a retrospective study of 161 consecutive patients (32% female, age 65 ± 10 years) who underwent repeat AF ablation after index PV isolation between 2010 and 2022. Demographics, procedural characteristics and follow-up data were collected. Recurrent atrial tachycardia (AT)/AF was defined as any atrial arrhythmia ≥30 s in duration. RESULTS: Compared to males, females tended to be older and had a significantly higher prevalence of prior valve surgery (10 vs. 2%; P = .03). At repeat ablation, PV reconnection was found in 119 (74%) patients. Males were more likely to have PV reconnection at repeat ablation compared to females (81 vs. 59%; P = .004). Excluding repeat PV isolation, there were no significant differences in adjunctive ablation strategies performed at repeat ablation between females and males. During follow-up, there were no significant differences in freedom from AT/AF recurrence between females and males after repeat ablation (63 vs. 59% at 2 years, respectively; P = .48). CONCLUSIONS: After initial PV isolation, significantly fewer females have evidence of PV reconnection at the time of repeat ablation for recurrent AF. Despite this difference, long-term freedom from AT/AF was similar between females and males after repeat ablation.

Localized Re-Entry Is a Frequent Mechanism of De Novo Atypical Flutter.

BACKGROUND: Limited data exist about the origins and mechanisms of atypical atrial flutter that occurs in the absence of prior ablation or surgery. OBJECTIVES: The aims of this study were to report a large cohort of patients who presented for catheter ablation of de novo atypical flutters, to identify the most common locations and mechanisms of arrhythmia, and to describe outcomes after ablation. METHODS: Demographic, electrophysiological, and outcome data were collected for patients who underwent ablation of de novo atypical flutter. RESULTS: The mechanisms of 85 atypical flutters were identified in 62 patients and localized to the left atrium (LA) in 58 and right atrium (RA) in 27. In the LA, mechanisms were classified as macro-re-entry in 29 (50%) and localized re-entry in 29 (50%), whereas in the RA, mechanisms were macro-re-entry in 8 (30%) and localized re-entry in 19 (70%) (proportion of localized re-entry in the LA vs. RA, P = 0.08). Nine patients had both localized and macro-re-entrant atypical flutters. In the LA, localized re-entry was commonly found in the anterior LA, followed by the pulmonary veins and septum. In the RA, localized re-entry was found at various sites, including the lateral or posterior RA, septum, and coronary sinus ostium. During 39.4 months (Q1-Q3: 18.2-65.8 months) of follow-up, atrial arrhythmias occurred in 66% of patients after a single ablation and in 50% after >1 ablation. Among patients who underwent repeat ablation, compared with the index arrhythmia, different tachycardia circuits or arrhythmias were documented in 13 of 18 cases (72%). CONCLUSIONS: Atypical atrial flutters in patients without prior surgery or complex ablation are often due to localized re-entry (approximately 50% in the LA and a higher frequency in the RA). Other atrial tachycardias commonly occur during long-term follow-up following ablation, suggesting progressive atrial myopathy in these patients.

Ventricular Tachycardia Due to Triggered Activity: Role of Early and Delayed Afterdepolarizations.

Most forms of sustained ventricular tachycardia (VT) are caused by re-entry, resulting from altered myocardial conduction and refractoriness secondary to underlying structural heart disease. In contrast, VT caused by triggered activity (TA) is unrelated to an abnormal structural substrate and is often caused by molecular defects affecting ion channel function or regulation of intracellular calcium cycling. This review summarizes the cellular and molecular bases underlying TA and exemplifies their clinical relevance with selective representative scenarios. The underlying basis of TA caused by delayed afterdepolarizations is related to sarcoplasmic reticulum calcium overload, calcium waves, and diastolic sarcoplasmic reticulum calcium leak. Clinical examples of TA caused by delayed afterdepolarizations include sustained right and left ventricular outflow tract tachycardia and catecholaminergic polymorphic VT. The other form of afterpotentials, early afterdepolarizations, are systolic events and inscribe early afterdepolarizations during phase 2 or phase 3 of the action potential. The fundamental defect is a decrease in repolarization reserve with associated increases in late plateau inward currents. Malignant ventricular arrhythmias in the long QT syndromes are initiated by early afterdepolarization-mediated TA. An understanding of the molecular and cellular bases of these arrhythmias has resulted in generally effective pharmacologic-based therapies, but these are nonspecific agents that have off-target effects. Therapeutic efficacy may need to be augmented with an implantable defibrillator. Next-generation therapies will include novel agents that rescue arrhythmogenic abnormalities in cellular signaling pathways and gene therapy approaches that transfer or edit pathogenic gene variants or silence mutant messenger ribonucleic acid.

Ventricular Arrhythmia in Cancer Patients: Mechanisms, Treatment Strategies and Future Avenues.

Cardiovascular disease and cancer are the leading causes of morbidity and mortality in the US. Despite the significant progress made in cancer treatment leading to improved prognosis and survival, ventricular arrhythmias (VA) remain a known cardiovascular complication either exacerbated or induced by the direct and indirect effects of both traditional and novel cancer treatments. Although interruption of cancer treatment because of VA is rarely required, knowledge surrounding this issue is essential for optimising the overall care of patients with cancer. The mechanisms of cancer-therapeutic-induced VA are poorly understood. This review will discuss the ventricular conduction (QRS) and repolarisation abnormalities (QTc prolongation), and VAs associated with cancer therapies, as well as existing strategies for the identification, prevention and management of cancer-treatment-induced VAs.

Low Utilization of Lead Extraction Among Patients With Infective Endocarditis and Implanted Cardiac Electronic Devices.

BACKGROUND: Cardiac implantable electronic device (CIED)-associated infections are associated with substantial morbidity, mortality, and costs. Guidelines have cited endocarditis as a Class I indication for transvenous lead removal/extraction (TLE) among patients with CIEDs. OBJECTIVES: The authors sought to study utilization of TLE among hospital admissions with infective endocarditis using a nationally representative database. METHODS: Using the Nationwide Readmissions Database (NRD), 25,303 admissions for patients with CIEDs and endocarditis between 2016 and 2019 were evaluated on the basis of International Classification of Diseases-10th Revision, Clinical-Modification (ICD-10-CM) codes. RESULTS: Among admissions for patients with CIEDs and endocarditis, 11.5% were managed with TLE. The proportion undergoing TLE increased significantly from 2016 to 2019 (7.6% vs 14.9%; P trend < 0.001). Procedural complications were identified in 2.7%. Index mortality was significantly lower among patients managed with TLE (6.0% vs 9.5%; P < 0.001). Presence of Staphylococcus aureus infection, implantable cardioverter-defibrillator, and large hospital size were independently associated with TLE management. TLE management was less likely with older age, female sex, dementia, and kidney disease. After adjustment for comorbidities, TLE was independently associated with significantly lower odds of mortality (adjusted OR: 0.47; 95% CI: 0.37-0.60 by multivariable logistic regression, and adjusted OR: 0.51; 95% CI: 0.40-0.66 by propensity score matching). CONCLUSIONS: Utilization of lead extraction among patients with CIEDs and endocarditis is low, even in the presence of low rates of procedural complications. Lead extraction management is associated with significantly lower mortality, and its use has trended upward between 2016 and 2019. Barriers to TLE for patients with CIEDs and endocarditis require investigation.

Early Stroke and Mortality After Percutaneous Left Atrial Appendage Occlusion in Patients With Atrial Fibrillation.

BACKGROUND: Percutaneous endocardial left atrial appendage occlusion (LAAO) is an alternative therapy for stroke prevention in patients with atrial fibrillation who are poor candidates for oral anticoagulants. Oral anticoagulation is generally discontinued 45 days following successful LAAO. Real-world data on early stroke and mortality following LAAO are lacking. METHODS: Using International Classification of Diseases, Tenth Revision, Clinical-Modification codes, we performed a retrospective observational registry analysis to examine the rates and predictors of stroke, mortality, and procedural complications during index hospitalization and 90-day readmission among 42 114 admissions in the Nationwide Readmissions Database for LAAO between 2016 and 2019. Early stroke and mortality were defined as events occurring during index admission or 90-day readmission. Data on timing of early strokes post-LAAO were collected. Multivariable logistic regression modeling was used to ascertain predictors of early stroke and major adverse events. RESULTS: LAAO was associated with low rates of early stroke (0.63%), early mortality (0.53%), and procedural complications (2.59%). Among patients who had readmissions with strokes after LAAO, the median time from implant to readmission was 35 days (interquartile range, 9-57 days); 67% of readmissions with strokes occurred <45 days postimplant. Between 2016 and 2019, the rates of early stroke after LAAO significantly decreased (0.64% versus 0.46% P-for-trend <0.001), while early mortality and major adverse event rates were unchanged. Peripheral vascular disease and a history of prior stroke were independently associated with early stroke after LAAO. Early post-LAAO stroke rates were similar between low, medium, and high LAAO volume tertile centers. CONCLUSIONS: In this contemporary real-world analysis, the early stroke rate after LAAO was low, with the majority occurring within 45 days of device implantation. Despite an increase in LAAO procedures between 2016 and 2019, there with a significant decline in early strokes after LAAO during that period.

Safety and Efficacy of a Novel Approach to Pulmonary Vein Isolation Using Prolonged Apneic Oxygenation.

BACKGROUND: Improved ablation catheter-tissue contact results in more effective ablation lesions. Respiratory motion causes catheter instability, which impacts durable pulmonary vein isolation (PVI). OBJECTIVES: This study sought to evaluate the safety and efficacy of a novel ablation strategy involving prolonged periods of apneic oxygenation during PVI. METHODS: We conducted a multicenter, prospective controlled study of 128 patients (mean age 63 ± 11 years; 37% women) with paroxysmal atrial fibrillation undergoing PVI. Patients underwent PVI under general anesthesia using serial 4-minute runs of apneic oxygenation (apnea group; n = 64) or using standard ventilation settings (control group; n = 64). Procedural data, arterial blood gas samples, catheter position coordinates, and ablation lesion characteristics were collected. RESULTS: Baseline characteristics between the 2 groups were similar. Catheter stability was significantly improved in the apnea group, as reflected by a decreased mean catheter displacement (1.55 ± 0.97 mm vs 2.25 ± 1.13 mm; P < 0.001) and contact force SD (4.9 ± 1.1 g vs 5.2 ± 1.5 g; P = 0.046). The percentage of lesions with a mean catheter displacement >2 mm was significantly lower in the apnea group (22% vs 44%; P < 0.001). Compared with the control group, the total ablation time to achieve PVI was reduced in the apnea group (18.8 ± 6.9 minutes vs 23.4 ± 7.8 minutes; P = 0.001). There were similar rates of first-pass PVI, acute PV reconnections and dormant PV reconnections between the two groups. CONCLUSIONS: A novel strategy of performing complete PVI during apneic oxygenation results in improved catheter stability and decreased ablation times without adverse events. (Radiofrequency Ablation of Atrial Fibrillation Under Apnea; NCT04170894).

Population-Level Prevalence of Rare Variants Associated With Atrial Fibrillation and its Impact on Patient Outcomes.

BACKGROUND: Whole exome sequencing may identify rare pathogenic/likely pathogenic variants (LPVs) that are linked to atrial fibrillation (AF). The impact of LPVs associated with AF on a population level on outcomes is unclear. OBJECTIVES: This study sought to examine the association of LPVs with AF and their impact on clinical outcomes using the UK Biobank, a national repository of participants with available whole exome sequencing data. METHODS: A total of 200,631 individuals in the UK Biobank were studied. Incident and prevalent AF, comorbidities, and outcomes were identified using self-reported assessments and hospital stay operative, and death registry records. LPVs were determined using arrhythmia and cardiomyopathy gene panels with LOFTEE and ClinVar to predict variants of functional significance. RESULTS: Compared with control subjects, there was a modestly increased prevalence of LPVs among 9,585 patients with AF (2.0% vs 1.7%, respectively; P = 0.01). Among those with prevalent AF at <45 years of age, 4.2% were LPV carriers. LPVs in TTN and PKP2 were associated with AF with adjusted odds ratios of 2.69 (95% CI: 1.57-4.61) and 2.69 (95% CI: 1.54-4.68), respectively. There was no significant difference in combined ischemic stroke, heart failure hospitalization, and mortality among patients who have AF with and without LPVs (25.1% vs 23.8%; P = 0.49). Among participants with AF and available cardiac magnetic resonance imaging data, LPV carriers had lower left ventricular ejection fractions than non-LPV carriers (42% vs 52%; P = 0.027). CONCLUSIONS: Patients with AF had a modestly increased prevalence of LPVs. Among reference arrhythmia and cardiomyopathy genes, the contribution of rare variants to AF risk at a population level is modest and its impact on outcomes appears to be limited, despite an association of LPVs with reduced left ventricular ejection fraction among patients with AF.

Initial experience with stylet-driven versus lumenless lead delivery systems for left bundle branch area pacing.

INTRODUCTION: Left bundle branch area pacing (LBBP) has emerged as an alternative method for conduction system pacing. While initial experience with delivery systems for stylet-driven and lumenless lead implantation for LBBP has been described, data comparing outcomes of stylet-driven versus lumenless lead implantation for LBBP are limited. In this study, we compare success rates and outcomes of LBBP with stylet-driven versus lumenless lead delivery systems. METHODS: Eighty-three consecutive patients (mean age 74.1 ± 11.2 years; 56 [68%] male) undergoing attempted LBBP at a single institution were identified. Cases were grouped by lead delivery systems used: stylet-driven (n = 53) or lumenless (n = 30). Baseline characteristics and procedural findings were recorded and compared between the cohorts. Intermediate term follow-up data on ventricular lead parameters were also compared. RESULTS: Baseline characteristics were similar between groups. Successful LBBP was achieved in 77% of patients, with similar success rates between groups (76% in stylet-driven, 80% in lumenless, p = 0.79), and rates of adjudicated LBB capture and other paced QRS parameters were also similar. Compared with the lumenless group, the stylet-driven group had significantly shorter procedure times (90 ± 4 vs. 112 ± 31 min, p = 0.004) and fluoroscopy times (10 ± 5 vs. 15 ± 6 min, p = 0.003). Ventricular lead parameters at follow-up were similar, and rates of procedural complications and need for lead revision were low in both groups. CONCLUSION: Delivery systems for stylet-driven and for lumenless leads for LBBP have comparable acute success rates. Long-term follow-up of lead performance following use of the various delivery systems is warranted.

Outcomes of patients with heart failure with preserved ejection fraction undergoing catheter ablation of atrial fibrillation.

Background: Limited real-world data exist on early outcomes in patients with heart failure with preserved ejection fraction (HFpEF) undergoing atrial fibrillation (AF) ablation. Objectives: The purpose of this study was to examine and compare rates of index procedural complications and 30-day readmissions after AF ablation in patients with HFpEF, with heart failure with reduced ejection fraction (HFrEF), and without heart failure. Methods: Using the Nationwide Readmissions Database (NRD), we examined 50,299 admissions of adults with heart failure undergoing AF catheter ablation between 2010 and 2014. Using ICD-9-CM codes, we identified procedural complications and causes of readmission after AF ablation. Results: From 2010 to 2014, the prevalence of HFpEF among patients undergoing AF ablation increased from 3.05% to 7.35% (P for trend <.001). Compared to patients without heart failure, patients with HFpEF had significantly increased procedural complications and index mortality (8.4% vs 6.2% and 0.30% vs 0.08%, respectively; P = .016 and P = .010, respectively). Index complication rates between patients with HFpEF and HFrEF were similar. All-cause 30-day readmissions occurred in 18.3% of patients with HFpEF compared to 9.5% of patients without heart failure (P <.001). Compared to no heart failure, the presence of HFpEF was independently associated with all-cause readmissions (adjusted odds ratio 1.52; 95% confidence interval 1.15-1.96; P = .002), but not with procedural complications, cardiac readmissions, or early mortality. Conclusion: Rates of 30-day readmissions after AF ablation are high in patients with HFpEF. However, after adjustment for age and comorbidities, complications and early mortality after AF ablation between patients with HFpEF and those without heart failure are comparable.

Reappraisal of electrocardiographic criteria for localization of idiopathic outflow region ventricular arrhythmias.

BACKGROUND: Electrocardiographic (ECG) criteria have been proposed to localize the site of origin of outflow region ventricular arrhythmias (VAs). Many factors influence the QRS morphology of VAs and may limit the accuracy of these criteria. OBJECTIVE: The purpose of this study was to assess the accuracy of ECG criteria that differentiate right from left outflow region VAs and localize VAs within the aortic sinus of Valsalva (ASV). METHODS: One hundred one patients (mean age 52 ± 16 years; 55 [54%] women) undergoing catheter ablation of right ventricular outflow tract (RVOT) or ASV VAs with a left bundle branch block, inferior axis morphology were studied. ECG measurements including V2 transition ratio, transition zone index, R-wave duration index, R/S amplitude index, V2S/V3R index, V1-3 QRS morphology, R-wave amplitude in the inferior leads were tabulated for all VAs. Comparisons were made between the predicted site of origin using these criteria and the successful ablation site. RESULTS: Patients had successful ablation of 71 RVOT and 38 ASV VAs. For the differentiation of RVOT from ASV VAs, the positive predictive values and negative predictive values for all tested ECG criteria ranged from 42% to 75% and from 71% to 82%, respectively, with the V2S/V3R index having the largest area under the curve of 0.852. Morphological QRS criteria in leads V1 through V3 did not localize ASV VAs. The maximum R-wave amplitude in the inferior leads was the sole criterion demonstrating a significant difference between right ASV, right-left ASV commissure, and left ASV sites. CONCLUSION: ECG criteria for differentiating right from left ventricular outflow region VAs and for localizing ASV VAs have a limited accuracy.

The Left Atrial Appendage Ostium: Hotspots for Localized Re-Entry.

OBJECTIVES: The goal of this study was to characterize the location and electrophysiological properties of left atrial appendage (LAA) atrial tachycardia (AT). BACKGROUND: The LAA has been reported to be a source of AT and atrial fibrillation (AF) triggers. METHODS: This study retrospectively reviewed ATs mapped to the LAA. Activation and entrainment mapping were used to determine the mechanism and localize each AT circuit/origin. RESULTS: From 2014 to 2018, a total of 45 patients (mean age 65 ± 10 years; 69% male) had 51 LAA ATs: 43 (84%) after AF ablation and 8 de novo (no prior AF). Overall, 50 (98%) were due to localized re-entry/micro-re-entry, whereas only 1 was a focal triggered AT. All 50 micro-re-entrant LAA ATs were mapped to the anterior base (70%) or LAA ridge (30%), and all were successfully treated with focal ablation; no case required LAA isolation. After successful ablation of the initial AT at the LAA base, 23 (62%) of 37 patients with AF also had inducible macro-re-entrant peri-mitral flutter, but none had AF triggers from inside the LAA. CONCLUSIONS: LAA ATs are almost always micro-re-entrant in mechanism and originate from either the anterior base or LAA ridge. AT originating from inside the LAA body is very rare. The anterior and ridge aspects of the LAA-left atrium junction seem to be arrhythmogenic hotspots prone to localized re-entry. These ATs are treatable with focal ablation without LAA isolation but are frequently associated with macro-re-entrant peri-mitral flutter.

Outcomes and mortality associated with atrial arrhythmias among patients hospitalized with COVID-19.

INTRODUCTION: The impact of atrial arrhythmias on coronavirus disease 2019 (COVID-19)-associated outcomes are unclear. We sought to identify prevalence, risk factors and outcomes associated with atrial arrhythmias among patients hospitalized with COVID-19. METHODS: An observational cohort study of 1053 patients with severe acute respiratory syndrome coronavirus 2 infection admitted to a quaternary care hospital and a community hospital was conducted. Data from electrocardiographic and telemetry were collected to identify atrial fibrillation (AF) or atrial flutter/tachycardia (AFL). The association between atrial arrhythmias and 30-day mortality was assessed with multivariable analysis. RESULTS: Mean age of patients was 62 ± 17 years and 62% were men. Atrial arrhythmias were identified in 166 (15.8%) patients, with AF in 154 (14.6%) patients and AFL in 40 (3.8%) patients. Newly detected atrial arrhythmias occurred in 101 (9.6%) patients. Age, male sex, prior AF, renal disease, and hypoxia on presentation were independently associated with AF/AFL occurrence. Compared with patients without AF/AFL, patients with AF/AFL had significantly higher levels of troponin, B-type natriuretic peptide, C-reactive protein, ferritin and d-dimer. Mortality was significantly higher among patients with AF/AFL (39.2%) compared to patients without (13.4%; p < .001). After adjustment for age and co-morbidities, AF/AFL (adjusted odds ratio [OR]: 1.93; p = .007) and newly detected AF/AFL (adjusted OR: 2.87; p < .001) were independently associated with 30-day mortality. CONCLUSION: Atrial arrhythmias are common among patients hospitalized with COVID-19. The presence of AF/AFL tracked with markers of inflammation and cardiac injury. Atrial arrhythmias were independently associated with increased mortality.

Inpatient hospital procedural volume and outcomes following catheter ablation of atrial fibrillation.

INTRODUCTION: The real-world distribution of hospital atrial fibrillation (AF) ablation volume and its impact on outcomes are not well-established. We sought to examine patient characteristics, complications, and readmissions after AF ablation stratified by hospital procedural volume. METHODS AND RESULTS: Using the nationally representative inpatient Nationwide Readmissions Database, we evaluated 54 597 admissions for AF ablation between 2010 and 2014. Hospitals were categorized according to tertiles of annual AF ablation volume. Index complications, 30-day readmissions, and early mortality were examined. Multivariable logistic regression was performed to assess the predictors of adverse outcomes. Between 2010 and 2014, low volume tertile hospitals accounted for 79.3% of hospitals performing AF ablations. When stratified by first, second, and third volume tertiles, complication and early mortality rates were higher in low volume centers (8.9% and 0.67% vs 6.1% and 0.33%, vs 4.5% and 0.16%, respectively; P < .001). Patients undergoing AF ablation at low volume centers were older and had a higher prevalence of congestive heart failure, coronary artery disease, and other comorbidities. Low volume hospitals were associated with increased cardiac perforation (adjusted odds ratio [aOR], 4.79; P < .001), vascular complications (aOR 1.49; P < .001), and any complication (aOR 2.06; P < .001) during index admission as well as increased early mortality (aOR 2.43; P = .039). CONCLUSIONS: Among patients hospitalized for AF ablation, low inpatient AF ablation hospital volume was associated with worse outcomes following ablation, which was exacerbated by a greater comorbidity burden among patients at these centers.