Patient characteristics, predictors and outcome of pacemaker patients upgraded to an implantable cardioverter defibrillator

AIMS

Pacemaker (PM) patients may require a subsequent upgrade to an implantable cardioverter defibrillator (ICD). Limited data exists on this patient population. We sought to characterize this population, to assess predictors for ICD upgrade, and to report the outcome.

METHODS

From our prospective PM and ICD implantation registry, all patients who underwent PM and/or ICD implantations at our center were analyzed. Patient characteristics and outcomes of PM patients with subsequent ICD upgrade were compared to age- and sex-matched patients with de novo ICD implantation, and to PM patients without subsequent upgrade.

RESULTS

Of 1'301 ICD implantations, 60 (5%) were upgraded from PMs. Median time from PM implantation to ICD upgrade was 2.6 years (IQR 1.3-5.4). Of 2'195 PM patients, 28 patients underwent subsequent ICD upgrades, corresponding to an estimated annual incidence of an ICD upgrade of at least 0.33%. Lower LVEF (p = .05) and male sex (p = .038) were independent predictors for ICD upgrade. Survival without death, transplant and LVAD implantation were worse both for upgraded ICD patients compared to matched patients with de novo ICD implantation (p = .05), as well as for PM patients with subsequent upgrade compared to matched PM patients not requiring an upgrade (p = .036).

CONCLUSIONS

One of 20 ICD implantations are upgrade of patients with a PM. At least one of 30 PM patients will require an ICD upgrade in the following 10 years. Predictors for ICD upgrade are male sex and lower LVEF at PM implantation. Upgraded patients have worse outcomes.

Catheter Ablation for Channelopathies: When Is Less More?

Ventricular fibrillation (VF) is a common cause of sudden cardiac death in patients with channelopathies, particularly in the young population. Although pharmacological treatment, cardiac sympathectomy, and implantable cardioverter defibrillators (ICD) have been the mainstay in the management of VF in patients with channelopathies, they are associated with significant adverse effects and complications, leading to poor quality of life. Given these drawbacks, catheter ablation has been proposed as a therapeutic option for patients with channelopathies. Advances in imaging techniques and modern mapping technologies have enabled increased precision in identifying arrhythmia triggers and substrate modification. This has aided our understanding of the underlying pathophysiology of ventricular arrhythmias in channelopathies, highlighting the roles of the Purkinje network and the epicardial right ventricular outflow tract in arrhythmogenesis. This review explores the role of catheter ablation in managing the most common channelopathies (Brugada syndrome, congenital long QT syndrome, short QT syndrome, and catecholaminergic polymorphic ventricular tachycardia). While the initial results for ablation in Brugada syndrome are promising, the long-term efficacy and durability of ablation in different channelopathies require further investigation. Given the genetic and phenotypic heterogeneity of channelopathies, future studies are needed to show whether catheter ablation in patients with channelopathies is associated with a reduction in VF, and psychological distress stemming from recurrent ICD shocks, particularly relative to other available therapeutic options (e.g., quinidine in high-risk Brugada patients).

Cardiovascular Disease Burden, Mortality, and Sudden Death Risk in Epilepsy: A UK Biobank Study

BACKGROUND

Sudden death is the leading cause of mortality in medically refractory epilepsy. Middle-aged persons with epilepsy (PWE) are under investigated regarding their mortality risk and burden of cardiovascular disease (CVD).

METHODS

Using UK Biobank, we identified 7786 (1.6%) participants with diagnoses of epilepsy and 6,171,803 person-years of follow-up (mean 12.30 years, standard deviation 1.74); 566 patients with previous histories of stroke were excluded. The 7220 PWE comprised the study cohort with the remaining 494,676 without epilepsy as the comparator group. Prevalence of CVD was determined using validated diagnostic codes. Cox proportional hazards regression was used to assess all-cause mortality and sudden death risk.

RESULTS

Hypertension, coronary artery disease, heart failure, valvular heart disease, and congenital heart disease were more prevalent in PWE. Arrhythmias including atrial fibrillation/flutter (12.2% vs 6.9%; P < 0.01), bradyarrhythmias (7.7% vs 3.5%; P < 0.01), conduction defects (6.1% vs 2.6%; P < 0.01), and ventricular arrhythmias (2.3% vs 1.0%; P < 0.01), as well as cardiac implantable electric devices (4.6% vs 2.0%; P < 0.01) were more prevalent in PWE. PWE had higher adjusted all-cause mortality (hazard ratio [HR], 3.9; 95% confidence interval [CI], 3.01-3.39), and sudden death-specific mortality (HR, 6.65; 95% CI, 4.53-9.77); and were almost 2 years younger at death (68.1 vs 69.8; P < 0.001).

CONCLUSIONS

Middle-aged PWE have increased all-cause and sudden death-specific mortality and higher burden of CVD including arrhythmias and heart failure. Further work is required to elucidate mechanisms underlying all-cause mortality and sudden death risk in PWE of middle age, to identify prognostic biomarkers and develop preventative therapies in PWE.

Unraveling Complexities in Genetically Elusive Long QT Syndrome

Genetic testing has become standard of care for patients with long QT syndrome (LQTS), providing diagnostic, prognostic, and therapeutic information for both probands and their family members. However, up to a quarter of patients with LQTS do not have identifiable Mendelian pathogenic variants in the currently known LQTS-associated genes. This absence of genetic confirmation, intriguingly, does not lessen the severity of LQTS, with the prognosis in these gene-elusive patients with unequivocal LQTS mirroring genotype-positive patients in the limited data available. Such a conundrum instigates an exploration into the causes of corrected QT interval (QTc) prolongation in these cases, unveiling a broad spectrum of potential scenarios and mechanisms. These include multiple environmental influences on QTc prolongation, exercise-induced repolarization abnormalities, and the profound implications of the constantly evolving nature of genetic testing and variant interpretation. In addition, the rapid advances in genetics have the potential to uncover new causal genes, and polygenic risk factors may aid in the diagnosis of high-risk patients. Navigating this multifaceted landscape requires a systematic approach and expert knowledge, integrating the dynamic nature of genetics and patient-specific influences for accurate diagnosis, management, and counseling of patients. The role of a subspecialized expert cardiogenetic clinic is paramount in evaluation to navigate this complexity. Amid these intricate aspects, this review outlines potential causes of gene-elusive LQTS. It also provides an outline for the evaluation of patients with negative and inconclusive genetic test results and underscores the need for ongoing adaptation and reassessment in our understanding of LQTS, as the complexities of gene-elusive LQTS are increasingly deciphered.

Comparison of the PolarX and the Arctic Front cryoballoon for pulmonary vein isolation in patients with symptomatic paroxysmal atrial fibrillation (COMPARE CRYO) - Study protocol for a randomized controlled trial

INTRODUCTION

Single-shot devices are increasingly used for pulmonary vein isolation (PVI) in atrial fibrillation (AF). The Arctic Front cryoballoon (Medtronic) is the most frequently used single-shot technology. A recently developed novel cryoballoon has been introduced (PolarX, Boston Scientific) with the aim to address limitations of the Arctic Front system.

METHODS

COMPARE CRYO is a multicentre, randomized, controlled trial with blinded endpoint adjudication by an independent clinical events committee. A total of 200 patients with paroxysmal AF undergoing their first PVI are randomized 1:1 between PolarX cryoballoon ablation and Arctic Front cryoballoon ablation. Continuous monitoring during follow-up is performed using an implantable cardiac monitor (ICM) in all patients. The primary endpoint is time to first recurrence of any atrial tachyarrhythmia (AF, atrial flutter, and/or atrial tachycardia) ≥ 120 s between days 91 and 365 post ablation as detected on the (ICM). Procedural safety is assessed by a composite of cardiac tamponade, persistent phrenic nerve palsy >24 h, vascular complications requiring intervention, stroke/transient ischemic attack, atrioesophageal fistula or death occurring during or up to 30 days after the procedure. Key secondary endpoints include (1) procedure and fluoroscopy times, (2) AF burden, (3) proportion of patients with recurrence in the blanking period, (4) proportion of patients undergoing repeat ablation, and (5) quality of life changes at 12 months compared to baseline.

CONCLUSION

COMPARE CRYO will compare the efficacy and safety of the novel PolarX cryoballoon and the standard-of-practice Arctic Front cryoballoon for first PVI performed in patients with symptomatic paroxysmal AF.

TRIAL REGISTRATION

(ClinicalTrials.gov ID: NCT04704986).

Beyond gene-disease validity: capturing structured data on inheritance, allelic requirement, disease-relevant variant classes, and disease mechanism for inherited cardiac conditions

BACKGROUND

As the availability of genomic testing grows, variant interpretation will increasingly be performed by genomic generalists, rather than domain-specific experts. Demand is rising for laboratories to accurately classify variants in inherited cardiac condition (ICC) genes, including secondary findings.

METHODS

We analyse evidence for inheritance patterns, allelic requirement, disease mechanism and disease-relevant variant classes for 65 ClinGen-curated ICC gene-disease pairs. We present this information for the first time in a structured dataset, CardiacG2P, and assess application in genomic variant filtering.

RESULTS

For 36/65 gene-disease pairs, loss of function is not an established disease mechanism, and protein truncating variants are not known to be pathogenic. Using the CardiacG2P dataset as an initial variant filter allows for efficient variant prioritisation whilst maintaining a high sensitivity for retaining pathogenic variants compared with two other variant filtering approaches.

CONCLUSIONS

Access to evidence-based structured data representing disease mechanism and allelic requirement aids variant filtering and analysis and is a pre-requisite for scalable genomic testing.

Toward advanced diagnosis and management of inherited arrhythmia syndromes: Harnessing the capabilities of artificial intelligence and machine learning

The use of advanced computational technologies, such as artificial intelligence (AI), is now exerting a significant influence on various aspects of life, including health care and science. AI has garnered remarkable public notice with the release of deep learning models that can model anything from artwork to academic papers with minimal human intervention. Machine learning, a method that uses algorithms to extract information from raw data and represent it in a model, and deep learning, a method that uses multiple layers to progressively extract higher-level features from the raw input with minimal human intervention, are increasingly leveraged to tackle problems in the health sector, including utilization for clinical decision support in cardiovascular medicine. Inherited arrhythmia syndromes are a clinical domain where multiple unanswered questions remain despite unprecedented progress over the past 2 decades with the introduction of large panel genetic testing and the first steps in precision medicine. In particular, AI tools can help address gaps in clinical diagnosis by identifying individuals with concealed or transient phenotypes; enhance risk stratification by elevating recognition of underlying risk burden beyond widely recognized risk factors; improve prediction of response to therapy, and further prognostication. In this contemporary review, we provide a summary of the AI models developed to solve challenges in inherited arrhythmia syndromes and also outline gaps that can be filled with the development of intelligent AI models.

Validation of a clinical model for predicting left versus right ventricular outflow tract origin of idiopathic ventricular arrhythmias

BACKGROUND

Prediction of the chamber of origin in patients with outflow tract ventricular arrhythmias (OTVA) remains challenging. A clinical risk score based on age, sex and presence of hypertension was associated with a left ventricular outflow tract (LVOT) origin. We aimed to validate this clinical score to predict an LVOT origin in patients with OTVA.

METHODS

In a two-center observational cohort study, unselected patients undergoing catheter ablation (CA) for OTVA were enrolled. All procedures were performed using an electroanatomical mapping system. Successful ablation was defined as a ≥80% reduction of the initial overall PVC burden after 3 months of follow-up. Patients with unsuccessful ablation were excluded from this analysis.

RESULTS

We included 187 consecutive patients with successful CA of idiopathic OTVA. Mean age was 52 ± 15 years, 102 patients (55%) were female, and 74 (40%) suffered from hypertension. A LVOT origin was found in 64 patients (34%). A score incorporating age, sex and presence of hypertension reached 73% sensitivity and 67% specificity for a low (0-1) and high (2-3) score, to predict an LVOT origin. The combination of one ECG algorithm (V2 S/V3 R-index) with the clinical score resulted in a sensitivity and specificity of 81% and 70% for PVCs with R/S transition at V3 .

CONCLUSION

The published clinical score yielded a lower sensitivity and specificity in our cohort. However, for PVCs with R/S transition at V3, the combination with an existing ECG algorithm can improve the predictability of LVOT origin.

Predicted Deleterious Variants in Cardiomyopathy Genes Prognosticate Mortality and Composite Outcomes in UK Biobank

BACKGROUND

Inherited cardiomyopathies present with broad variation of phenotype. Data are limited regarding genetic screening strategies and outcomes associated with predicted deleterious variants in cardiomyopathy-associated genes in the general population.

OBJECTIVES

The authors aimed to determine the risk of mortality and composite cardiomyopathy-related outcomes associated with predicted deleterious variants in cardiomyopathy-associated genes in the UK Biobank.

METHODS

Using whole exome sequencing data, variants in dilated, hypertrophic, and arrhythmogenic right ventricular cardiomyopathy-associated genes with at least moderate evidence of disease causality according to ClinGen Expert Panel curations were annotated using REVEL (≥0.65) and ANNOVAR (predicted loss-of-function) considering gene-disease mechanisms. Genotype-positive and genotype-negative groups were compared using time-to-event analyses for the primary (all-cause mortality) and secondary outcomes (diagnosis of cardiomyopathy; composite outcome of diagnosis of cardiomyopathy, heart failure, arrhythmia, stroke, and death).

RESULTS

Among 200,619 participants (age at recruitment 56.46 ± 8.1 years), 5,292 (2.64%) were found to host ≥1 predicted deleterious variants in cardiomyopathy-associated genes (CMP-G+). After adjusting for age and sex, CMP-G+ individuals had higher risk for all-cause mortality (HR: 1.13 [95% CI: 1.01-1.25]; P = 0.027), increased risk for being diagnosed with cardiomyopathy later in life (HR: 5.75 [95% CI: 4.58-7.23]; P < 0.0001), and elevated risk for composite outcome (HR: 1.29 [95% CI: 1.20-1.39]; P < 0.0001) than CMP-G- individuals. The higher risk for being diagnosed with cardiomyopathy and composite outcomes in the genotype-positive subjects remained consistent across all cardiomyopathy subgroups.

CONCLUSIONS

Adults with predicted deleterious variants in cardiomyopathy-associated genes exhibited a slightly higher risk of mortality and a significantly increased risk of developing cardiomyopathy, and cardiomyopathy-related composite outcomes, in comparison with genotype-negative controls.

Pulsed-field ablation for the treatment of left atrial reentry tachycardia

BACKGROUND

We describe our initial experience using a multipolar pulsed-field ablation catheter for the treatment of left atrial (LA) reentry tachycardia.

METHODS

We included all patients with LA reentry tachycardia treated with PFA at our institution between September 2021 and March 2022. The tachycardia mechanism was identified using 3D electro-anatomical mapping (3D-EAM). Subsequently, a roof line, anterior line, or mitral isthmus line was ablated as appropriate. Roof line ablation was always combined with LA posterior wall (LAPW) ablation. Positioning of the PFA catheter was guided by a 3D-EAM system and by fluoroscopy. Bidirectional block across lines was verified using standard criteria. Additional radiofrequency ablation (RFA) was used to achieve bidirectional block as necessary.

RESULTS

Among 22 patients (median age 70 (59-75) years; 9 females), we identified 27 LA reentry tachycardia: seven roof dependent macro-reentries, one posterior-wall micro-reentry, twelve peri-mitral macro-reentries, and seven anterior-wall micro-reentries. We ablated a total of 20 roof lines, 13 anterior lines, and 6 mitral isthmus lines. Additional RFA was necessary for two anterior lines (15%) and three mitral isthmus lines (50%). Bidirectional block was achieved across all roof lines, 92% of anterior lines, and 83% of mitral isthmus lines. We observed no acute procedural complications.

CONCLUSION

Ablation of a roof line and of the LAPW is feasible, effective, and safe using this multipolar PFA catheter. However, the catheter is less suited for ablation of the mitral isthmus and the anterior line. A focal pulsed-field ablation catheter may be more effective for ablation of these lines. This study shows the feasibility to ablate linear lesions with a multipolar pulsed-field ablation catheter. 27 left atrial reentry tachycardia were treated in 22 patients.

Genetic mechanisms underlying arrhythmogenic mitral valve prolapse: Current and future perspectives

Mitral valve prolapse (MVP) is a heart valve disease that is often familial, affecting 2%-3% of the general population. MVP with or without mitral regurgitation can be associated with an increased risk of ventricular arrhythmias and sudden cardiac death (SCD). Research on familial MVP has specifically focused on genetic factors, which may explain the heritable component of the disease estimated to be present in 20%-35%. Furthermore, the structural and electrophysiological substrates underlying SCD/ventricular arrhythmia risk in MVP have been studied postmortem and in the electrophysiology laboratory, respectively. Understanding how familial MVP and rhythm disorders are related may help patients with MVP by individualizing risk and working to develop effective management strategies. This contemporary, state-of-the-art, expert review focuses on genetic factors and familial components that underlie MVP and arrhythmia and encapsulates clinical, genetic, and electrophysiological issues that should be the objectives of future research.

Arrhythmias and Clinical Outcomes in a Swiss Multicenter Cohort of Patients With Dextro-Transposition of the Great Arteries and Atrial Switch

Background Data on the incidence of arrhythmias, associated cardiac interventions, and outcome in patients with dextro-transposition of the great arteries and atrial switch are scarce. Methods and Results In this multicenter analysis, we included adult patients with dextro-transposition of the great arteries and atrial switch regularly followed up at 3 Swiss tertiary care hospitals. The primary outcome was a composite of left ventricular assist device, heart transplantation, and death. The secondary outcome was occurrence of ventricular tachycardia, ventricular fibrillation, or sudden cardiac death. We identified 207 patients (34% women; median age at last follow-up, 35 years) with dextro-transposition of the great arteries and atrial switch. Arrhythmias occurred in 97 patients (47%) at a median age of 22 years. A pacemaker or an implantable cardioverter-defibrillator was implanted in 39 (19%) and 13 (6%) patients, respectively, and 33 (16%) patients underwent a total of 51 ablation procedures to target 60 intra-atrial re-entry tachycardias, 4 atrioventricular nodal re-entry tachycardias, and 1 atrial fibrillation. The primary outcome occurred in 21 patients (10%), and the secondary outcome occurred in 18 patients (9%); both were more common in patients with concomitant ventricular septum defect than in those without (hazard ratio [HR], 3.06 [95% CI, 1.29-7.27], P=0.011; and HR, 3.62 [95% CI, 1.43-9.18], P=0.007, respectively). Conclusions In patients with dextro-transposition of the great arteries and atrial switch reaching adulthood, arrhythmias occur in almost half of patients, and associated rhythm interventions are frequent. One-tenth of those patients do not survive until the age of 35 years free from left ventricular assist device or heart transplantation, and the outcome is worse in patients with concomitant ventricular septum defect.

Infectious Endocarditis of a Heterotopic Caval Valved Stent

Right-sided infective endocarditis (IE) accounts for 5% to 10% of all IE cases. Compared with left-sided IE, it is more often associated with intravenous drug abuse and intracardiac devices, whereas the latter has become more prevalent in recent decades. The authors report the first case of IE in a heterotopic caval valved stent used for treating torrential tricuspid regurgitation. (Level of Difficulty: Advanced.).

Beyond gene-disease validity: capturing structured data on inheritance, allelic-requirement, disease-relevant variant classes, and disease mechanism for inherited cardiac conditions

Background

As availability of genomic testing grows, variant interpretation will increasingly be performed by genomic generalists, rather than domain-specific experts. Demand is rising for laboratories to accurately classify variants in inherited cardiac condition (ICC) genes, including as secondary findings.

Methods

We analyse evidence for inheritance patterns, allelic requirement, disease mechanism and disease-relevant variant classes for 65 ClinGen-curated ICC gene-disease pairs. We present this information for the first time in a structured dataset, CardiacG2P, and assess application in genomic variant filtering.

Results

For 36/65 gene-disease pairs, loss-of-function is not an established disease mechanism, and protein truncating variants are not known to be pathogenic. Using CardiacG2P as an initial variant filter allows for efficient variant prioritisation whilst maintaining a high sensitivity for retaining pathogenic variants compared with two other variant filtering approaches.

Conclusions

Access to evidence-based structured data representing disease mechanism and allelic requirement aids variant filtering and analysis and is pre-requisite for scalable genomic testing.

Acute and Long-term Outcomes of quadripolar IS-4 versus bipolar IS-1 Left Ventricular Leads in Cardiac Resynchronization Therapy: A Retrospective Registry Study

BACKGROUND

The implantation procedure of left ventricular (LV) leads and the management of cardiac resynchronization therapy (CRT) patients can be challenging. The IS-4 standard for CRT offers additional pacing vectors compared to bipolar leads (IS-1). IS-4 leads improve procedural outcome and may also result in lower adverse events during follow-up (FU) and improve clinical outcome in CRT patients. Further long-term FU data comparing the two lead designs are necessary.

METHODS

In this retrospective, single-center study we included adult patients implanted with a CRT-Defibrillator (CRT-D) or CRT-Pacemaker (CRT-P) with a quadripolar (IS-4 group) or bipolar (IS-1 group) LV lead and with available ≥3 years clinical FU. The combined primary endpoint was a combination of predefined, lead-related adverse events. Secondary endpoints were all single components of the primary endpoint.

RESULTS

Overall, 133 patients (IS-4 n = 66; IS-1 n = 67) with a mean FU of 4.03±1.93 years were included. Lead-related adverse events were less frequent in patients with an IS-4 lead than with an IS-1 lead (n = 8, 12.1% vs. n = 23, 34.3%; p = 0.002). The secondary outcomes showed a lower rate of LV lead deactivation/explantation and LV lead dislodgement/dysfunction (4.5% vs 22.4%; p = 0.003; 4.5% vs. 17.9%; p = 0.015, respectively) in the IS-4 patient group. Less patients suffered from unresolved phrenic nerve stimulation with an IS-4 lead (3.0% vs. 13.4%; p = 0.029). LV lead-related re-interventions were fewer in case of an IS-4 lead (6.1% vs. 17.9%; p = 0.036).

CONCLUSION

In this retrospective analysis, the IS-4 LV lead is associated with lower lead-related complication rates than the IS-1 lead at long-term FU. This article is protected by copyright. All rights reserved.

Identification of Cx43 variants predisposing to ventricular fibrillation in the acute phase of ST-elevation myocardial infarction

AIMS

Ventricular fibrillation (VF) occurring in the acute phase of ST-elevation myocardial infarction (STEMI) is the leading cause of sudden cardiac death worldwide. Several studies showed that reduced connexin 43 (Cx43) expression and reduced conduction velocity increase the risk of VF in acute myocardial infarction (MI). Furthermore, genetic background might predispose individuals to primary VF (PVF). The primary objective was to evaluate the presence of GJA1 variants in STEMI patients. The secondary objective was to evaluate the arrhythmogenic impact of GJA1 variants in STEMI patients with VF.

METHODS AND RESULTS

The MAP-IDM prospective cohort study included 966 STEMI patients and was designed to identify genetic predisposition to VF. A total of 483 (50.0%) STEMI patients with PVF were included. The presence of GJA1 variants increased the risk of VF in STEMI patients [from 49.1 to 70.8%, P = 0.0423; odds ratio (OR): 0.40; 95% confidence interval: 0.16-0.97; P = 0.04]. The risk of PVF decreased with beta-blocker intake (from 53.5 to 44.8%, P = 0.0085), atrial fibrillation (from 50.7 to 26.4%, P = 0.0022), and with left ventricular ejection fraction >50% (from 60.2 to 41.4%, P < 0.0001). Among 16 GJA1 variants, three novel heterozygous missense variants were identified in three patients: V236I, H248R, and I327M. In vitro studies of these variants showed altered Cx43 localization and decreased cellular communication, mainly during acidosis.

CONCLUSION

Connexin 43 variants are associated with increased VF susceptibility in STEMI patients. Restoring Cx43 function may be a potential therapeutic target to prevent PVF in patients with acute MI.

CLINICAL TRIAL REGISTRATION

Clinical Trial Registration: https://clinicaltrials.gov/ct2/show/NCT00859300.

Acute Coronary Occlusion in Patients With Non-ST-Segment Elevation Out-of-Hospital Cardiac Arrest

BACKGROUND

According to current guidelines, hemodynamic status should guide the decision between immediate and delayed coronary angiography (CAG) in out-of-hospital cardiac arrest (OHCA) patients without ST-segment elevation. A delayed strategy is advised in hemodynamically stable patients, and an immediate approach is recommended in unstable patients.

OBJECTIVES

This study sought to assess the frequency, predictors, and clinical impact of acute coronary occlusion in hemodynamically stable and unstable OHCA patients without ST-segment elevation.

METHODS

Consecutive unconscious OHCA patients without ST-segment elevation who were undergoing CAG at Bern University Hospital (Bern, Switzerland) between 2011 and 2019 were included. Frequency and predictors of acute coronary artery occlusions and their impact on all-cause and cardiovascular mortality at 1 year were assessed.

RESULTS

Among the 386 patients, 169 (43.8%) were hemodynamically stable. Acute coronary occlusions were found in 19.5% of stable and 24.0% of unstable OHCA patients (P = 0.407), and the presence of these occlusions was predicted by initial chest pain and shockable rhythm, but not by hemodynamic status. Acute coronary occlusion was associated with an increased risk of cardiovascular death (adjusted HR: 2.74; 95% CI: 1.22-6.15) but not of all-cause death (adjusted HR: 0.72; 95% CI: 0.44-1.18). Hemodynamic instability was not predictive of fatal outcomes.

CONCLUSIONS

Acute coronary artery occlusions were found in 1 in 5 OHCA patients without ST-segment elevation. The frequency of these occlusions did not differ between stable and unstable patients, and the occlusions were associated with a higher risk of cardiovascular death. In OHCA patients without ST-segment elevation, chest pain or shockable rhythm rather than hemodynamic status identifies patients with acute coronary occlusion.

Sex-related differences in incidence, phenotype and risk of sudden cardiac death in inherited arrhythmia syndromes

Inherited Arrhythmia Syndromes (IAS) including long QT and Brugada Syndrome, are characterized by life-threatening arrhythmias in the absence of apparent structural heart disease and are caused by pathogenic variants in genes encoding cardiac ion channels or associated proteins. Studies of large pedigrees of families affected by IAS have demonstrated incomplete penetrance and variable expressivity. Biological sex is one of several factors that have been recognized to modulate disease severity in IAS. There is a growing body of evidence linking sex hormones to the susceptibility to arrhythmias, yet, many sex-specific disease aspects remain underrecognized as female sex and women with IAS are underinvestigated and findings from male-predominant cohorts are often generalized to both sexes with minimal to no consideration of relevant sex-associated differences in prevalence, disease manifestations and outcome. In this review, we highlight current knowledge of sex-related biological differences in normal cardiac electrophysiology and sex-associated factors that influence IAS phenotypes.

SGLT2 inhibitor therapy for transthyretin amyloid cardiomyopathy: early tolerance and clinical response to dapagliflozin

AIMS

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) improve clinical outcomes in heart failure patients with reduced and preserved left ventricular ejection fraction (LVEF), but have not yet been investigated in transthyretin amyloid cardiomyopathy (ATTR-CM). This study aimed to evaluate tolerability, clinical outcomes, and changes in NT-proBNP levels and glomerular filtration rate (GFR) in ATTR-CM patients treated with dapagliflozin.

METHODS AND RESULTS

Patients with stable, tafamidis-treated ATTR-CM were retrospectively evaluated at the initiation of dapagliflozin and 3 months thereafter. Tafamidis-treated ATTR-CM patients without SGLT2i served as a reference cohort. Overall, SLGT2i therapy was initiated in 34 patients. Seventeen patients with stable disease on tafamidis, who were subsequently started on dapagliflozin, were included in the analysis. Patients selected for SGLT2i presented with signs of advanced disease, evidenced by higher Gillmore disease stage (stage ≥2: 53% vs. 27.5%; P = 0.041), baseline median NT-proBNP [median (IQR) 2668 pg/mL (1314-3451) vs. 1424 (810-2059); P = 0.038] and loop diuretic demand (76.5% vs. 45% of patients; P = 0.044), and lower LVEF (46.6 ± 12.9 vs. 53.7 ± 8.7%; P = 0.019) and GFR (51.8 ± 16.5 vs. 68.5 ± 18.6 mL/min; P = 0.037) compared with the reference cohort. At 3-month follow-up, a numerical decrease in NT-proBNP levels was observed in 13/17 (76.5%) patients in the dapagliflozin (-190 pg/mL, IQR: -1,028-71, P = 0.557) and 27/40 (67.5%) of patients in the control cohort (-115 pg/mL, IQR: -357-105, P = 0.551). Other disease parameters remained stable and no adverse events occurred.

CONCLUSIONS

In tafamidis-treated ATTR-CM patients, initiation of dapagliflozin was well tolerated. The efficacy of SGLT2i therapy in patients with ATTR-CM needs to be studied in randomized controlled trials.

Frequency of Arrhythmias and Postural Orthostatic Tachycardia Syndrome in Patients With Marfan Syndrome: A Nationwide Inpatient Study

Background Marfan syndrome (MFS) is an autosomal dominant connective tissue disorder affecting multiple systems, particularly the cardiovascular system. The leading causes of death in MFS are aortopathies and valvular disease. We wanted to identify the frequency of arrhythmia and postural orthostatic tachycardia syndrome, length of hospital stay, health care-associated costs (HAC), and in-hospital mortality in patients with MFS. Methods and Results The National Inpatient Sample database from 2005 to 2014 was queried using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes for MFS and arrhythmias. Patients were classified into subgroups: supraventricular tachycardia, ventricular tachycardia (VT), atrial fibrillation, atrial flutter, and without any type of arrhythmia. Data about length of stay, HAC, and in-hospital mortality were also abstracted from National Inpatient Sample database. Adjusted HAC was calculated as multiplying HAC and cost-to-charge ratio; 12 079 MFS hospitalizations were identified; 1893 patients (15.7%) had an arrhythmia; and 4.9% of the patients had postural orthostatic tachycardia syndrome. Median values of length of stay and adjusted HAC in VT group were the highest among the groups (VT: 6 days, $18 975.8; supraventricular tachycardia: 4 days, $11 906.6; atrial flutter: 4 days, $11 274.5; atrial fibrillation: 5 days, $10431.4; without any type of arrhythmia: 4 days, $8336.6; both P=0.0001). VT group had highest in-patient mortality (VT: 5.3%, atrial fibrillation: 4.1%, without any type of arrhythmia: 2.1%, atrial flutter: 1.7%, supraventricular tachycardia: 0%; P<0.0001) even after adjustment for potential confounders (without any type of arrhythmia versus VT; odds ratio [95% CI]: 3.18 [1.62-6.24], P=0.001). Conclusions Arrhythmias and postural orthostatic tachycardia syndrome in MFS were high and associated with increased length of stay, HAC, and in-hospital mortality especially in patients with VT.

Genotype-Specific ECG-Based Risk Stratification Approaches in Patients With Long-QT Syndrome

Background

Congenital long-QT syndrome (LQTS) is a major cause of sudden cardiac death (SCD) in young individuals, calling for sophisticated risk assessment. Risk stratification, however, is challenging as the individual arrhythmic risk varies pronouncedly, even in individuals carrying the same variant.

Materials and Methods

In this study, we aimed to assess the association of different electrical parameters with the genotype and the symptoms in patients with LQTS. In addition to the heart-rate corrected QT interval (QTc), markers for regional electrical heterogeneity, such as QT dispersion (QT_max-QT_min in all ECG leads) and delta T_peak/end (T_peak/end V5 – T_peak/end V2), were assessed in the 12-lead ECG at rest and during exercise testing.

Results

QTc at rest was significantly longer in symptomatic than asymptomatic patients with LQT2 (493.4 ms ± 46.5 ms vs. 419.5 ms ± 28.6 ms, p = 0.004), but surprisingly not associated with symptoms in LQT1. In contrast, post-exercise QTc (minute 4 of recovery) was significantly longer in symptomatic than asymptomatic patients with LQT1 (486.5 ms ± 7.0 ms vs. 463.3 ms ± 16.3 ms, p = 0.04), while no such difference was observed in patients with LQT2. Enhanced delta T_peak/end and QT dispersion were only associated with symptoms in LQT1 (delta T_peak/end 19.0 ms ± 18.1 ms vs. −4.0 ms ± 4.4 ms, p = 0.02; QT-dispersion: 54.3 ms ± 10.2 ms vs. 31.4 ms ± 10.4 ms, p = 0.01), but not in LQT2. Delta T_peak/end was particularly discriminative after exercise, where all symptomatic patients with LQT1 had positive and all asymptomatic LQT1 patients had negative values (11.8 ± 7.9 ms vs. −7.5 ± 1.7 ms, p = 0.003).

Conclusion

Different electrical parameters can distinguish between symptomatic and asymptomatic patients in different genetic forms of LQTS. While the classical “QTc at rest” was only associated with symptoms in LQT2, post-exercise QTc helped distinguish between symptomatic and asymptomatic patients with LQT1. Enhanced regional electrical heterogeneity was only associated with symptoms in LQT1, but not in LQT2. Our findings indicate that genotype-specific risk stratification approaches based on electrical parameters could help to optimize risk assessment in LQTS.

Frequency, Penetrance, and Variable Expressivity of Dilated Cardiomyopathy-Associated Putative Pathogenic Gene Variants in UK Biobank Participants

BACKGROUND

There is a paucity of data regarding the phenotype of dilated cardiomyopathy (DCM) gene variants in the general population. We aimed to determine the frequency and penetrance of DCM-associated putative pathogenic gene variants in a general adult population, with a focus on the expression of clinical and subclinical phenotype, including structural, functional, and arrhythmic disease features.

METHODS

UK Biobank participants who had undergone whole exome sequencing, ECG, and cardiovascular magnetic resonance imaging were selected for study. Three variant-calling strategies (1 primary and 2 secondary) were used to identify participants with putative pathogenic variants in 44 DCM genes. The observed phenotype was graded DCM (clinical or cardiovascular magnetic resonance diagnosis); early DCM features, including arrhythmia or conduction disease, isolated ventricular dilation, and hypokinetic nondilated cardiomyopathy; or phenotype-negative.

RESULTS

Among 18 665 individuals included in the study, 1463 (7.8%) possessed ≥1 putative pathogenic variant in 44 DCM genes by the main variant calling strategy. A clinical diagnosis of DCM was present in 0.34% and early DCM features in 5.7% of individuals with putative pathogenic variants. ECG and cardiovascular magnetic resonance analysis revealed evidence of subclinical DCM in an additional 1.6% and early DCM features in an additional 15.9% of individuals with putative pathogenic variants. Arrhythmias or conduction disease (15.2%) were the most common early DCM features, followed by hypokinetic nondilated cardiomyopathy (4%). The combined clinical/subclinical penetrance was ≤30% with all 3 variant filtering strategies. Clinical DCM was slightly more prevalent among participants with putative pathogenic variants in definitive/strong evidence genes as compared with those with variants in moderate/limited evidence genes.

CONCLUSIONS

In the UK Biobank, ≈1 of 6 of adults with putative pathogenic variants in DCM genes exhibited early DCM features potentially associated with DCM genotype, most commonly manifesting with arrhythmias in the absence of substantial ventricular dilation or dysfunction.

Validation of a multipolar pulsed-field ablation catheter for endpoint assessment in pulmonary vein isolation procedures

AIMS

To validate the performance of a multipolar pulsed-field ablation (PFA) catheter compared to a standard pentaspline 3D-mapping catheter for endpoint assessment of pulmonary vein isolation (PVI). PFA for PVI using single-shot devices combines the benefits of high procedural efficacy and safety. A newly available multipolar PFA catheter allows real-time recording of pulmonary vein (PV) signals during PVI.

METHODS AND RESULTS

Patients undergoing first PVI using PFA with the standard ablation protocol (eight applications per PV) were studied. Entrance and exit block (10 V/2 ms) were assessed using the PFA catheter. Subsequently, a high-density 3D electroanatomical bipolar voltage map (3D-EAM) was constructed using a standard pentaspline 3D-mapping catheter. Additional PFA applications were delivered only after confirmation of residual PV connection by 3D-EAM. In 56 patients, 213 PVs were targeted for ablation. Acute PVI was achieved in 100% of PVs: in 199/213 (93%) PVs with the standard ablation protocol alone and in the remaining 14 PVs after additional PFA applications. The accuracy of PV assessment with the PFA catheter after the standard ablation protocol was 91% (194/213 veins). In 5/213 (2.3%) PVs, the PFA catheter incorrectly indicated PV-isolation. In 14/213 (6.6%), the PFA catheter incorrectly indicated residual PV-conduction due to high-output pace-capture. Lowering the output to 5 V/1 ms reduced this observation to 0.9% (2/213) and increased the overall accuracy to 97% (206/213).

CONCLUSION

A novel multipolar PFA catheter allows reliable endpoint assessment for PVI. Due to its design, far-field sensing and high-output pace-capture can occur. Lowering the pacing output increases the accuracy from 91 to 97%.

Gender gap in study inclusion: Insights from the STAR-FIB cohort study

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): Swiss National Science Foundation Swiss Heart Foundation

Background

The underrepresentation of women in cardiovascular clinical trials is well described but cannot be fully explained by sex-specific differences in the prevalence of cardiovascular diseases. Data on potential sex- and gender-related differences in study exclusion reasons are scarce.

The STAR-FIB cohort study aimed to estimate the age and sex-specific prevalence of screening-detected atrial fibrillation (AF) in 800 hospitalized patients aged 65-84 years using serial seven-day ECGs. Recruitment for study inclusion was stratified by sex (female/male, as stated in the patient’s records) and age (four age bands, ≥65 to &lt;70, ≥70 to &lt;75, ≥75 to &lt;80, and ≥80 to &lt;85 years), and was truncated for each subgroup after the inclusion of 100 participants.

Purpose

To assess sex and gender differences in patient recruitment for inclusion in the STAR-FIB cohort study.

Methods

A screening log containing sex-category, age, and reasons for exclusion was maintained. Exclusion criteria are shown in the figure. For the purpose of the present study, an explorative analysis of all exclusion criteria with respect to sex category was done.

Results

Overall, 11’470 patients were identified for eligibility, 795 patients (49% women; mean age 75 years) were enrolled, and 10’675 patients (52% women vs. 48% men, p =0.13) were not enrolled. The two major exclusion reasons were unwillingness to participate, which was more frequent in women (27.9% of women vs. 18.4% of men, p &lt; 0.01), and the presence of clinical AF, which was more prevalent in men (27.1% of men vs. 20.5 % of women, p &lt; 0.01). A detailed analysis of all exclusion criteria analysed by sex category is provided in the figure.

Conclusions

Clinical AF was more frequent in men, in accordance with the well described sex-driven (biological) higher prevalence of AF in men. In contrast, we found a higher percentage of women unwilling to participate in this study, which may represent a more gender-based (sociocultural) phenomenon. A further exploration of these findings should be performed and may help to identify and potentially overcome modifiable obstacles for study participation.

Pulsed field ablation of atrial fibrillation: recurrence rate after first pulmonary vein isolation and first insights into durability at redo procedures

Funding Acknowledgements

Type of funding sources: None.

Background

Pulsed field ablation (PFA) is newly available for pulmonary vein isolation (PVI) and combines the benefits of high procedural efficacy and safety. Independent data on the recurrence-rate of atrial fibrillation (AF) after PVI and on PVI durability during redo procedures are scarce.

Purpose

We report data on the recurrence rate of AF after first PVI using PFA and first insights into findings of PVI durability during redo procedures.

Methods

Consecutive AF patients undergoing a first PFA PVI at our center between May 2021 and August 2021 were included. PVI was verified by 3D-electroanatomical mapping (3D-EAM), and additional PFA lesions were applied when necessary until all PV were isolated. Seven-day Holter ECGs were performed at 3 and 6 months after ablation. After a blanking period of 3 months, episodes of AF/AT lasting more than 30 seconds were considered as AF-recurrence.

Results

41 Patients, median age 69 (interquartile range 62-73) years, 24% female, 56% persistent AF, underwent first PVI by PFA. All PVs were successfully isolated using a multipolar PFA catheter. Median total procedure time including 3D-EAM was 104 (85-121) min. Total fluoroscopy time and dose were 26 (19-30) min and 671 (323-1248) Gym2. Acute complications occurred in 1 (2.4%) patient (cardiac tamponade requiring drainage). Early recurrence of AF during the blanking period occurred in 1 (2.4%) patient. Median follow-up time was 107 (91-152) days. Recurrence of AF after the blanking period was detected in 5 (12%) patients, 1 (6%) in paroxysmal AF and 4 (17%) in persistent AF patients, respectively. Redo procedures in 3 (7.3%) patients with AF recurrence confirmed durable isolation of 12/12 (100%) pulmonary veins and showed no evidence of PFA lesion regression.

Conclusion

AF recurrence rates after PVI by means of PFA are low. Durable isolation of 12/12 pulmonary veins (100%) and no evidence of PFA lesion regression was observed during redo procedures in patients with AF recurrence.

Comparison of the accuracy of contact force measurement in four commercially available force-sensing ablation catheters

Funding Acknowledgements

Type of funding sources: None.

Background

Contact force-sensing catheters are widely used for ablation of cardiac arrhythmias. They allow precise quantification of catheter-to-tissue contact, which is an important determinant of lesion size and durability. Moreover, contact force information reduces the risk for cardiac perforation and is used for estimation of lesion size. However, the accuracy of contact force sensors across different manufacturers has not been validated independently.

Objective

To compare the accuracy and reproducibility of different force sensing catheters used in cardiac electrophysiology procedures.

Methods

A force measurement setup containing a heated saline water bath and a catheter fixation mechanism was constructed. The setup allows to accurately measure forces applied to a platform with the catheter. We studied four different catheter models, equipped with the following, unique force-measurement technologies (figure 1): 1) multiple-fiber optical sensor; 2) single-fiber optical sensor; 3) inductive sensor; and 4) magnetic field sensors. For each model, we assessed three catheters. Repeated measurements within the force range of 0g to 60g and at electrode-tissue contact angles of 0°, 45°, and 90° were performed and validated against the force measurement unit of our measurement setup.

Results

For each catheter, at least 500 measurements at different contact forces (equally distributed across the measurement range of 0 to 60 grams) were performed. Correlation of measured-force to real-force was ρSpearman=0.99 for MFOS, ρSpearman=0.98 for SFOS, ρSpearman=0.99 for IS, and ρSpearman=0.98 for MFS. MFS and SFOS showed a higher variance for high forces and increased intra-catheter variability compared to MFOS and IS. IS overestimated higher contact force at 0° and 30°. MFS and SFOS underestimated contact force for higher forces at 30° and 45° (figure 2). Within a clinical range of 5g to 40g, the catheters reached the following root-mean-square-error, independent of contact angle: MFOS 0.88g ±0.68g, SFOS 2.15g ±1.74g, IS 0.88g ±0.72g, and MFS 1.13g ±1.01g.

Conclusion

Measured contact by force-sensing catheters correlates well with true exerted electrode-tissue force. Despite an excellent overall correlation, some technologies may be prone to significant errors at higher forces (&gt;10g under-/overestimation of true contact force) with potential clinical consequences related to increased risk of perforation.

Validation of a multipolar pulsed field ablation catheter for endpoint assessment in pulmonary vein isolation procedures

Funding Acknowledgements

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): FP7/2007-2013, №602299, EU-CERT-ICD

Objective

To validate the performance of a multipolar PFA catheter compared to a standard pentaspline 3D-mapping catheter for endpoint assessment of PVI.

Background

Pulsed field ablation (PFA) for pulmonary vein isolation (PVI) using single-shot devices combines the benefits of high procedural efficacy and safety. A newly available multipolar PFA catheter allows real-time recording of pulmonary vein (PV) signals during PVI.

Methods

Patients undergoing first PVI using PFA with the standard ablation protocol (8 applications per PV) were studied. Entrance- and exit-block (10V/2ms) were assessed using the PFA catheter. Subsequently, a high-density bipolar voltage 3D electro-anatomical map (3D-EAM) was constructed using a standard pentaspline 3D-mapping catheter. Additional PFA applications were delivered only after confirmation of residual PV-connection by 3D-EAM.

Results

In 56 patients, 213 PVs were targeted for ablation. Acute PVI was achieved in 100% of PVs: in 199/213 (93%) PVs with the standard ablation protocol alone and in the remaining 14 PVs after additional PFA applications. Accuracy of PV assessment with the PFA catheter after the standard ablation protocol was 91% (194/213 veins). In 5/213 (2.3%) PVs, the PFA catheter incorrectly indicated PV-isolation. In 14/213 (6.6%) the PFA catheter incorrectly indicated residual PV-conduction due to high-output pace-capture. When the output was reduced to 5V/1ms, pace-capture was reduced to 0.9% (2/213).

Conclusion

A novel multipolar PFA catheter allows reliable endpoint assessment for PVI. Due to its design, far-field sensing and high-output pace-capture can occur, which may require adjustment of standard pacing outputs for verification of exit-block.

Electrophysiological differences of deep sedation with dexmedetomidine versus propofol

Funding Acknowledgements

Type of funding sources: None.

Background

Dexmedetomidine and propofol are commonly used drugs for deep sedation during cardiovascular interventions. Patients undergoing these interventions often have impaired sinus node function or atrioventricular (AV) conduction disease. Anesthetics used for deep sedation may further compromise sinus node function and AV nodal conduction, and thereby interfere with the intervention.

Purpose

To compare the electrophysiological effects of dexmedetomidine and propofol on the function of the sinus node and AV conduction.

Methods

We randomized patients undergoing first atrial fibrilation ablation 1:1 to deep sedation by dexmedetomidine (DEX group) versus propofol (PRO group), according to a standardized protocol. At the end of the ablation procedure with the patients still deeply sedated and hemodynamically stable, we conducted a standard electrophysiological study and assessed sinus node function, properties of AV conduction and atrial refractoriness.

Results

Of 160 patients (65±11 years old; 32% female) included into the study, 80 patients were randomized to the DEX and PRO group each. Procedure duration (128±59 minutes) and sedation depth, as assessed by the "Modified Observer’s Assessment of Alertness/Sedation" score (median 3; interquartile range 2, 3), was not different among groups. DEX group patients received a mean of 231±111 mcg of dexmedetomidine and PRO group patients a mean of 657±356 mg of propofol. The table shows the results of the electrophysiological study. DEX group patients had lower sinus rate and longer unadjusted sinus node recovery time (SNRT) at pacing cycle lengths of 600, 500 and 400 ms. However, both corrected (SNRT-RR) and normalized (SNRT/RR) SNRT did not differ among groups. Compared to PRO group patients, AV nodal conduction was slower in DEX group patients as evidenced by longer PR and AH intervals, and a higher Wenckebach cycle length and AV node effective refractory period (ERP) was observed. Conduction properties in the His-Purkinje system were not different among groups, as QRS width and HV interval were similar. An arrhythmia, mainly atrial fibrillation, was induced in 33 patients (21%) during the electrophysiological study, without differences among groups.

Conclusions

Sinus rate and AV conduction are slower during deep sedation with dexmedetomidine compared to propofol. These differences in electrophysiological effects need to be taken into account when using these anesthetics during cardiovascular interventions.

Patient characteristics, predictors and outcome of pacemaker patients upgraded to an implantable cardioverter defibrillator

Funding Acknowledgements

Type of funding sources: None.

Introduction

Pacemaker (PM) patients may require a later upgrade to an implantable cardioverter-defibrillator (ICD). Limited data exists on this patient population. We sought to characterize this population, to assess predictors for ICD upgrade, and to report the outcome.

Methods

From our prospective PM and ICD implantation registry, all patients who underwent PM and/or ICD implantations at our center were analyzed. Patient characteristics and outcome of PM patients with subsequent ICD upgrade were compared to age- and sex-matched patients with de novo ICD implantation, and to PM patients without later upgrade.

Results

Of 1’301 ICD implantations, 60 (5%) were upgrades from PMs. Median time from PM implantation to ICD upgrade was 2.6 years (IQR 1.3-5.4) Of 2’195 PM patients, 28 patients underwent subsequent ICD upgrade, corresponding to an estimated annual incidence of an ICD upgrade of at least 0.33%. Lower LVEF (p=0.05) and male sex (p=0.038) were independent predictors for ICD upgrade. Transplant- and LVAD-free survival was worse both for upgraded ICD patients compared to matched patients with de novo ICD implantation (p=0.05; Figure, panel A), as well as for PM patients with later upgrade compared to matched PM patients not requiring an upgrade (p=0.036; Figure, panel B).

Conclusions

One of twenty ICD implantations are upgrades of patients with a PM. At least one of 30 PM patients will require an ICD upgrade in the following 10 years. Predictors for ICD upgrade are male sex and lower LVEF at PM implantation. Upgraded patients have worse outcome.

Arrhythmia burden, rhythm interventions and outcome in a large Swiss multicenter population of d-TGA patients with atrial switch

Funding Acknowledgements

Type of funding sources: None.

Background

Patients with dextro-transposition of the great arteries (d-TGA) and atrial switch face a high life-time risk of arrhythmias.

Purpose

To describe the incidence of arrhythmias, associated cardiac interventions and outcome in a large Swiss population of patients with d-TGA and atrial switch.

Methods

In this multicenter analysis we included all consecutive patients with d-TGA and atrial switch treated at three Swiss tertiary care hospitals. The primary outcome was survival free from left ventricular assist device (LVAD), heart transplantation (HTx) and death. The secondary outcome was survival free from ventricular tachycardia, ventricular fibrillation and sudden cardiac death.

Results

We identified 207 patients (34% females; median age at last follow-up 35 years) with d-TGA and atrial switch. Arrhythmias occurred in 97 patients (47%) at a median age of 22 years. A pacemaker or an implantable cardioverter/defibrillator was implanted in 39 (19%) and 13 (6%) patients, respectively, and 33 (16%) underwent a total of 51 ablation procedures to target 60 intra-atrial reentry tachycardias, 4 AV nodal reentry tachycardias and one atrial fibrillation (Figure 1). The primary outcome occurred in 21 patients (10%) and the secondary outcome in 18 (9%) (Figure 2). Primary and secondary outcomes were more common in patients with concomitant ventricular septum defect (VSD) than in those without (hazard ratio [HR] 3.06; 95% confidence interval [CI] 1.29-7.27, p=0.011; and HR 3.62; 95% CI 1.43-9.18, p=0.007, respectively).

Conclusions

At a median age of 35 years, arrhythmias occur in almost half of patients with d-TGA and atrial switch and associated rhythm interventions are frequent. One in ten patients does not survive free from LVAD and HTx and outcome is worse in patients with concomitant VSD.

Durability of CLOSE-guided pulmonary vein isolation in persistent atrial fibrillation - First results from a prospective remapping study

Funding Acknowledgements

Type of funding sources: None.

Background

The CLOSE protocol for pulmonary vein isolation (CLOSE-PVI) combines ablation index and inter-lesion distance (≤6 mm) targets. CLOSE-PVI has been shown to result in high clinical success rates. Data on durability of PVI after CLOSE-PVI mainly derive from repeat procedures in paroxysmal atrial fibrillation (AF) patients with recurrent AF.

Purpose

We sought to assess the incidence of pulmonary vein (PV) reconnections during a staged redo procedure performed independently of AF recurrence 6 months after CLOSE-PVI in patients with persistent AF.

Methods

In this prospective, single-center study, patients with symptomatic persistent AF (EHRA score &gt;1) undergoing AF ablation were included. Close-PVI was performed during the index procedure. A blanking period of 3 months was applied. Seven-day Holter ECGs were performed at 3 and 6 months post ablation. All patients underwent a staged redo procedure including high-density voltage mapping of the left atrium at 6 months after the index procedure.

Results

Overall, 20 patients were included (median age: 68 years [IQR 63-71]; 20% women; median duration of persistent AF: 8 months [IQR 5-15]; median LAVI 45 ml/m2 [IQR 43-53]). All PVs were successfully isolated with CLOSE-PVI during the index procedure. Four patients (20%) had AF recurrence. The redo procedure was performed after a median of 6.1 months (IQR 5.6-7.3). Of 80 PVs, 71 (89%) were still isolated. No patient had a common ostium. Reconnections were observed in 3 left superior (15%), in one left inferior (5%), in one right superior (5%) and in 4 right inferior (20%) PVs. Fourteen patients (74%) had completely isolated PVs. Two of four patients with AF recurrence (50%) and 12 of 16 patients without AF recurrence (75%) had completely isolated PVs (p=0.33).

Conclusions

CLOSE-PVI achieves durable PVI after 6 months in the majority of patients with persistent AF. In half of persistent AF patients with recurrence after CLOSE-PVI, all PVs are still isolated. These patients may need adjunctive ablation.

The Pathogenesis and Long-Term Consequences of COVID-19 Cardiac Injury

•

COVID-19 myocardial injury results from immune and hypercoagulability responses.

•

Long-term cardiac consequences of COVID-19 include structural and functional changes.

•

Myocarditis after COVID-19 vaccination is uncommon (highest risk in teenage males).

•

Larger population-based studies are necessary to validate these early results.

The mechanisms of coronavirus disease-2019 (COVID-19)–related myocardial injury comprise both direct viral invasion and indirect (hypercoagulability and immune-mediated) cellular injuries. Some patients with COVID-19 cardiac involvement have poor clinical outcomes, with preliminary data suggesting long-term structural and functional changes. These include persistent myocardial fibrosis, edema, and intraventricular thrombi with embolic events, while functionally, the left ventricle is enlarged, with a reduced ejection fraction and new-onset arrhythmias reported in a number of patients. Myocarditis post-COVID-19 vaccination is rare but more common among young male patients. Larger studies, including prospective data from biobanks, will be useful in expanding these early findings and determining their validity.

Differences in Atrial Remodeling in Hypertrophic Cardiomyopathy Compared to Hypertensive Heart Disease and Athletes' Hearts

Background: Hypertrophic cardiomyopathy (HCM), hypertensive heart disease (HHD) and athletes’ heart share an increased prevalence of atrial fibrillation. Atrial cardiomyopathy in these patients may have different characteristics and help to distinguish these conditions. Methods: In this single-center study, we prospectively collected and analyzed electrocardiographic (12-lead ECG, signal-averaged ECG (SAECG), 24 h Holter ECG) and echocardiographic data in patients with HCM and HHD and in endurance athletes. Patients with atrial fibrillation were excluded. Results: We compared data of 27 patients with HCM (70% males, mean age 50 ± 14 years), 324 patients with HHD (52% males, mean age 75 ± 5.5 years), and 215 endurance athletes (72% males, mean age 42 ± 7.5 years). HCM patients had significantly longer filtered P-wave duration (153 ± 26 ms) and PR interval (191 ± 48 ms) compared to HHD patients (144 ± 16 ms, p = 0.012 and 178 ± 31, p = 0.034, respectively) and athletes (134 ± 14 ms, p = 0.001 and 165 ± 26 ms, both p < 0.001, respectively). HCM patients had a mean of 4.9 ± 16 premature atrial complexes per hour. Premature atrial complexes per hour were significantly more frequent in HHD patients (27 ± 86, p < 0.001), but not in athletes (2.7 ± 23, p = 0.639). Left atrial volume index (LAVI) was 43 ± 14 mL/m2 in HCM patients and significantly larger than age- and sex-corrected LAVI in HHD patients 30 ± 10 mL/m2; p < 0.001) and athletes (31 ± 9.5 mL/m2; p < 0.001). A borderline interventricular septum thickness ≥13 mm and ≤15 mm was found in 114 (35%) HHD patients, 12 (6%) athletes and 3 (11%) HCM patients. Conclusions: Structural and electrical atrial remodeling is more advanced in HCM patients compared to HHD patients and athletes.

Dexmedetomidine versus Propofol for Operator-Directed Nurse-Administered Procedural Sedation during Catheter Ablation of Atrial Fibrillation: a Randomized Controlled Study

BACKGROUND

Operator-directed nurse-administered (ODNA) sedation with propofol is the preferred sedation technique for catheter ablation of atrial fibrillation (AF) in many centers.

OBJECTIVE

We aimed to investigate whether Dexmedetomidine, an α2-adrenergic receptor agonist, is superior to propofol.

METHODS

We randomized 160 consecutive patients undergoing first AF ablation to ODNA sedation by dexmedetomidine (DEX group) versus propofol (PRO group), according to a standardized protocol. Patients were unaware of treatment allocation. The primary endpoint was a composite of inefficient sedation, termination/change of sedation protocol or procedure abortion, hypercapnia (transcutaneous CO2 >55 mmHg), hypoxemia (SpO₂ <90%) or intubation, prolonged hypotension (systolic blood pressure <80 mmHg), and sustained bradycardia necessitating cardiac pacing. Secondary endpoints were the components of the primary endpoint and patient satisfaction with procedural sedation, as assessed by a standardized questionnaire the day following ablation.

RESULTS

The primary endpoint occurred in 15 DEX group and 25 PRO group patients (19% vs. 31%; p=0.068). Hypercapnia was significantly more frequent in PRO group patients (29% vs. 10%; p=0.003). There was no significant difference among the other components of the primary endpoint, no procedure was aborted. Patient satisfaction was significantly better in PRO group patients (visual analog scale 0-100; median 100 in PRO group vs. median 93 in DEX group; p<0.001).

CONCLUSION

Efficacy of ODNA sedation with dexmedetomidine was not different to propofol. Hypercapnia occurs less frequent with dexmedetomidine, but patient satisfaction is better with propofol sedation. In selected patients, dexmedetomidine may be used as an alternative to propofol for ODNA sedation during AF ablation. (ClinicalTrials.gov number NCT03844841).

Inflammation and Immune Response in Arrhythmogenic Cardiomyopathy: State-of-the-Art Review

Arrhythmogenic cardiomyopathy (ACM) is a primary disease of the myocardium, predominantly caused by genetic defects in proteins of the cardiac intercalated disc, particularly, desmosomes. Transmission is mostly autosomal dominant with incomplete penetrance. ACM also has wide phenotype variability, ranging from premature ventricular contractions to sudden cardiac death and heart failure. Among other drivers and modulators of phenotype, inflammation in response to viral infection and immune triggers have been postulated to be an aggravator of cardiac myocyte damage and necrosis. This theory is supported by multiple pieces of evidence, including the presence of inflammatory infiltrates in more than two-thirds of ACM hearts, detection of different cardiotropic viruses in sporadic cases of ACM, the fact that patients with ACM often fulfill the histological criteria of active myocarditis, and the abundance of anti-desmoglein-2, antiheart, and anti-intercalated disk autoantibodies in patients with arrhythmogenic right ventricular cardiomyopathy. In keeping with the frequent familial occurrence of ACM, it has been proposed that, in addition to genetic predisposition to progressive myocardial damage, a heritable susceptibility to viral infections and immune reactions may explain familial clustering of ACM. Moreover, considerable in vitro and in vivo evidence implicates activated inflammatory signaling in ACM. Although the role of inflammation/immune response in ACM is not entirely clear, inflammation as a driver of phenotype and a potential target for mechanism-based therapy warrants further research. This review discusses the present evidence supporting the role of inflammatory and immune responses in ACM pathogenesis and proposes opportunities for translational and clinical investigation.

Impact of clinical risk factor profile vs. atrial fibrillation phenotype on outcome after pulmonary vein isolation

Aims

Catheter ablation for atrial fibrillation (AF) is increasingly performed. Both clinical risk factors as well as the AF phenotype have been shown to influence ablation outcomes. The inter-relationship of the two however is incompletely understood.

Methods

In a retrospective analysis of a prospective registry of patients undergoing a first pulmonary vein isolation, the association of 8 predefined clinical risk factors (age &gt;70 years, female gender, hypertension, BMI &gt;30 kg/m2, coronary artery disease, heart failure, chronic kidney disease (CKD; eGFR&lt;60ml/min/1.73m2) and diabetes mellitus) and the AF phenotype (paroxysmal vs. persistent AF) were assessed as well as their impact on AF recurrence during follow-up.

Results

Overall, 715 patients were enrolled (median age 63 years, 27% females, 69% paroxysmal AF). The prevalence of obesity, hypertension, heart failure and CKD was significantly higher in persistent AF, while female gender was more prevalent in paroxysmal AF. After 2 years of follow-up, overall freedom from recurrence was 46%, and was higher in paroxysmal AF compared to persistent AF (54.1% vs. 29.1%, p&lt;0.001). Of the clinical risk factors, obesity (p=0.02), CKD (p=0.01) and heart failure (p=0.01) were significantly associated with lower arrhythmia-free survival, and there was a trend for hypertension and coronary artery disease (both p&lt;0.2). A risk score composed of those 5 factors was associated with recurrences in patients with paroxysmal AF (p=0.04, Figure 1), but not in those with persistent AF (p=0.85, Figure 2).

Conclusion

Clinical risk factors predict outcome after pulmonary vein isolation in patients with paroxysmal, but not persistent AF. This is likely due to a strong association of those risk factors with the occurrence of persistent AF.

Funding Acknowledgement

Type of funding sources: None. Figure 1Figure 2

Genetic basis and molecular biology of cardiac arrhythmias in cardiomyopathies

Cardiac arrhythmias are common, often the first, and sometimes the life-threatening manifestations of hereditary cardiomyopathies. Pathogenic variants in several genes known to cause hereditary cardiac arrhythmias have also been identified in the sporadic cases and small families with cardiomyopathies. These findings suggest a shared genetic aetiology of a subset of hereditary cardiomyopathies and cardiac arrhythmias. The concept of a shared genetic aetiology is in accord with the complex and exquisite interplays that exist between the ion currents and cardiac mechanical function. However, neither the causal role of cardiac arrhythmias genes in cardiomyopathies is well established nor the causal role of cardiomyopathy genes in arrhythmias. On the contrary, secondary changes in ion currents, such as post-translational modifications, are common and contributors to the pathogenesis of arrhythmias in cardiomyopathies through altering biophysical and functional properties of the ion channels. Moreover, structural changes, such as cardiac hypertrophy, dilatation, and fibrosis provide a pro-arrhythmic substrate in hereditary cardiomyopathies. Genetic basis and molecular biology of cardiac arrhythmias in hereditary cardiomyopathies are discussed.

Impact of contact force sensing technology on outcome of catheter ablation of idiopathic pre-mature ventricular contractions originating from the outflow tracts

AIMS

Catheter ablation of frequent idiopathic pre-mature ventricular contractions (PVC) is increasingly performed. While potential benefits of contact force (CF)-sensing technology for atrial fibrillation ablation have been assessed in several studies, the impact of CF-sensing on ventricular arrhythmia ablation remains unknown. This study aimed to compare outcomes of idiopathic outflow tract PVC ablation when using standard ablation catheters as opposed to CF-sensing catheters.

METHODS AND RESULTS

In a retrospective multi-centre study, unselected patients undergoing catheter ablation of idiopathic outflow tract PVCs between 2013 and 2016 were enrolled. All procedures were performed using irrigated-tip ablation catheters and a 3D electro-anatomical mapping system. Sustained ablation success was defined as a  ≥80% reduction of pre-procedural PVC burden determined by 24 h Holter ECG during follow-up. Overall, 218 patients were enrolled (median age 52 years, 51% males). Baseline and procedural data were similar in the standard ablation (24%) and the CF-sensing group (76%). Overall, the median PVC burden decreased from 21% (IQR 10-30%) before ablation to 0.2% (IQR 0-3.0%) after a median follow-up of 2.3 months (IQR 1.4-3.9 months). The rates of both acute (91% vs. 91%, P = 0.94) and sustained success (79% vs. 74%, P = 0.44) were similar in the standard ablation and the CF-sensing groups. No differences were observed in subgroups according to arrhythmia origin from the RVOT (65%) or LVOT (35%). Complications were rare (1.8%) and evenly distributed between the two groups.

CONCLUSION

The use of CF-sensing technology is not associated with increased success rate nor decreased complication rate in idiopathic outflow tract PVC ablation.

Evidence-Based Assessment of Genes in Dilated Cardiomyopathy

BACKGROUND

Each of the cardiomyopathies, classically categorized as hypertrophic cardiomyopathy, dilated cardiomyopathy (DCM), and arrhythmogenic right ventricular cardiomyopathy, has a signature genetic theme. Hypertrophic cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy are largely understood as genetic diseases of sarcomere or desmosome proteins, respectively. In contrast, >250 genes spanning >10 gene ontologies have been implicated in DCM, representing a complex and diverse genetic architecture. To clarify this, a systematic curation of evidence to establish the relationship of genes with DCM was conducted.

METHODS

An international panel with clinical and scientific expertise in DCM genetics evaluated evidence supporting monogenic relationships of genes with idiopathic DCM. The panel used the Clinical Genome Resource semiquantitative gene-disease clinical validity classification framework with modifications for DCM genetics to classify genes into categories on the basis of the strength of currently available evidence. Representation of DCM genes on clinically available genetic testing panels was evaluated.

RESULTS

Fifty-one genes with human genetic evidence were curated. Twelve genes (23%) from 8 gene ontologies were classified as having definitive (BAG3, DES, FLNC, LMNA, MYH7, PLN, RBM20, SCN5A, TNNC1, TNNT2, TTN) or strong (DSP) evidence. Seven genes (14%; ACTC1, ACTN2, JPH2, NEXN, TNNI3, TPM1, VCL) including 2 additional ontologies were classified as moderate evidence; these genes are likely to emerge as strong or definitive with additional evidence. Of these 19 genes, 6 were similarly classified for hypertrophic cardiomyopathy and 3 for arrhythmogenic right ventricular cardiomyopathy. Of the remaining 32 genes (63%), 25 (49%) had limited evidence, 4 (8%) were disputed, 2 (4%) had no disease relationship, and 1 (2%) was supported by animal model data only. Of the 16 evaluated clinical genetic testing panels, most definitive genes were included, but panels also included numerous genes with minimal human evidence.

CONCLUSIONS

In the curation of 51 genes, 19 had high evidence (12 definitive/strong, 7 moderate). It is notable that these 19 genes explain only a minority of cases, leaving the remainder of DCM genetic architecture incompletely addressed. Clinical genetic testing panels include most high-evidence genes; however, genes lacking robust evidence are also commonly included. We recommend that high-evidence DCM genes be used for clinical practice and that caution be exercised in the interpretation of variants in variable-evidence DCM genes.

Efficacy and safety of ethanol infusion into the vein of Marshall for mitral isthmus ablation

INTRODUCTION

Chemical ablation by retrograde infusion of ethanol into the vein of Marshall (VOM-EI) can facilitate the achievement of mitral isthmus block. This study sought to describe the efficacy and safety of this technique.

METHODS AND RESULTS

Twenty-two consecutive patients (14 males, median age 71 years) with attempted VOM-EI for mitral isthmus ablation were included in the study. VOM-EI was successfully performed with a median of 4 ml of 96% ethanol in 19 patients (86%) and the mitral isthmus was successfully blocked in all (100%). Touch up endocardial and/or epicardial ablation after VOM-EI was necessary for 12 patients (63%). Perimitral flutter was present in 12 patients (63%) during VOM-EI and terminated or slowed by VOM-EI in 4 and 3 patients, respectively. The low-voltage area of the mitral isthmus region increased from 3.1 cm² (interquartile range [IQR] 0-7.9) before to 13.2 cm² (IQR: 8.2-15.0) after VOM-EI and correlated significantly with the volume of ethanol injected (p = .03). Median high-sensitive cardiac troponin-T increased significantly from 330 ng/L (IQR: 221-516) the evening of the procedure to 598 ng/L (IQR: 382-769; p = .02) the following morning. A small pericardial effusion occurred in three patients (16%), mild pericarditis in one (5%), and uneventful VOM dissection in two (11%). After a median follow-up of 3.5 months (IQR: 3.0-11.0), 10 of 18 patients (56%) with VOM-EI and available follow-up had arrhythmia recurrence. Repeat ablation was performed in five patients (50%) and peri-mitral flutter diagnosed in three (60%).

CONCLUSION

VOM-EI is feasible, safe, and effective to achieve acute mitral isthmus block.