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Background: Atrioventricular (AV) conduction ablation has been achieved by targeting the area of penetration of the conduction axis as defined by recording a His bundle potential. Ablation of the His bundle may reduce the possibility of a robust junctional escape rhythm. It was hypothesised that specific AV nodal ablation is feasible and safe. Methods: The anatomical position of the AV node in relation to the site of penetration of the conduction axis was identified as described in dissections and histological sections of human hearts. Radiofrequency (RF) ablation was accomplished based on the anatomical criteria. Results: Specific anatomical ablation of the AV node was attempted in 72 patients. Successful AV nodal ablation was accomplished in 63 patients (87.5%), following 60 minutes (IQR 50–70 minutes) of procedure time, 3.4 minutes (IQR 2.4–5.5 minutes) of fluoroscopy time, and delivery of 4 (IQR 3–6) RF lesions. Αn escape rhythm was present in 45 patients (71%), and the QRS complex was similar to that before ablation in all 45 patients. Atropine was administered in six patients after the 10-min waiting period and did not result in restoration of conduction. In nine patients, AV conduction could not be interrupted, and AV block was achieved with ablation of the His after delivery of 12 (IQR 8–15) RF lesions. No cases of sudden death were encountered, and all patients had persistent AV block during a median 10.5 months (IQR 5–14 months) of follow-up. Conclusion: Anatomical ablation of the AV node is feasible and safe, and results in an escape rhythm similar to that before ablation.

Background: Atrial fibrillation (AF) patients are at high risk of stroke with ∼90% clots originating from the left atrial appendage (LAA). Clinical understanding of blood-flow based parameters and their potential association with stroke for AF patients remains poorly understood. We hypothesize that slow blood-flow either in the LA or the LAA could lead to the formation of blood clots and is associated with stroke for AF patients. Methods: We retrospectively collected cardiac CT images of paroxysmal AF patients and dichotomized them based on clinical event of previous embolic event into stroke and non-stroke groups. After image segmentation to obtain 3D LA geometry, patient-specific blood-flow analysis was performed to model LA hemodynamics. In terms of geometry, we calculated area of the pulmonary veins (PVs), mitral valve, LA and LAA, orifice area of LAA and volumes of LA and LAA and classified LAA morphologies. For hemodynamic assessment, we quantified blood flow velocity, wall shear stress (WSS, blood-friction on LA wall), oscillatory shear index (OSI, directional change of WSS) and endothelial cell activation potential (ECAP, ratio of OSI and WSS quantifying slow and oscillatory flow) in the LA as well as the LAA. Statistical analysis was performed to compare the parameters between the groups. Results: Twenty-seven patients were included in the stroke and 28 in the non-stroke group. Examining geometrical parameters, area of left inferior PV was found to be significantly higher in the stroke group as compared to non-stroke group (p = 0.026). In terms of hemodynamics, stroke group had significantly lower blood velocity (p = 0.027), WSS (p = 0.018) and higher ECAP (p = 0.032) in the LAA as compared to non-stroke group. However, LAA morphologic type did not differ between the two groups. This suggests that stroke patients had significantly slow and oscillatory circulating blood-flow in the LAA, which might expose it to potential thrombogenesis. Conclusion: Slow flow in the LAA alone was associated with stroke in this paroxysmal AF cohort. Patient-specific blood-flow analysis can potentially identify such hemodynamic conditions, aiding in clinical stroke risk stratification of AF patients.

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetic cardiac disease that leads to ventricular tachycardia (VT), a life-threatening heart rhythm disorder. Treating ARVC remains challenging due to the complex underlying arrhythmogenic mechanisms, which involve structural and electrophysiological (EP) remodeling. Here, we developed a novel genotype-specific heart digital twin (Geno-DT) approach to investigate the role of pathophysiological remodeling in sustaining VT reentrant circuits and to predict the VT circuits in ARVC patients of different genotypes. This approach integrates the patient’s disease-induced structural remodeling reconstructed from contrast-enhanced magnetic-resonance imaging and genotype-specific cellular EP properties. In our retrospective study of 16 ARVC patients with two genotypes: plakophilin-2 (PKP2, n = 8) and gene-elusive (GE, n = 8), we found that Geno-DT accurately and non-invasively predicted the VT circuit locations for both genotypes (with 100%, 94%, 96% sensitivity, specificity, and accuracy for GE patient group, and 86%, 90%, 89% sensitivity, specificity, and accuracy for PKP2 patient group), when compared to VT circuit locations identified during clinical EP studies. Moreover, our results revealed that the underlying VT mechanisms differ among ARVC genotypes. We determined that in GE patients, fibrotic remodeling is the primary contributor to VT circuits, while in PKP2 patients, slowed conduction velocity and altered restitution properties of cardiac tissue, in addition to the structural substrate, are directly responsible for the formation of VT circuits. Our novel Geno-DT approach has the potential to augment therapeutic precision in the clinical setting and lead to more personalized treatment strategies in ARVC.

Abstract Aims Atrial fibrillation (AF) is a common comorbid condition in heart failure with preserved ejection fraction (HFpEF). The effect of AF on heart failure (HF) exacerbation in HFpEF has not been well described. This study investigated how AF modifies the clinical trajectory of HFpEF patients after hospitalization for decompensated HF. Methods and results We stratified HFpEF subjects by AF diagnosis and performed longitudinal analysis to compare risk for HF hospitalization after index hospitalization for decompensated HF. All‐cause mortality, 30 day all‐cause readmissions, and response to inpatient diuresis were also evaluated. Of 90 subjects enrolled, 35.6% (n = 32) had AF. Subjects with AF were older (72.5 vs. 60.5 years; P

Inherited forms of arrhythmogenic and dilated cardiomyopathy (ACM and DCM) are characterized by variable disease expression and age-related penetrance. Calcium (Ca2+) is crucially important for proper cardiac function, and dysregulation of Ca2+ homeostasis seems to underly cardiomyopathy etiology. A polymorphism, c.286T>G p.(Ser96Ala), in the gene encoding the histidine-rich Ca2+ binding (HRC) protein, relevant for sarcoplasmic reticulum Ca2+ cycling, has previously been associated with a marked increased risk of life-threatening arrhythmias among idiopathic DCM patients. Following this finding, we investigated whether p.(Ser96Ala) affects major cardiac disease manifestations in carriers of the phospholamban (PLN) c.40_42delAGA; p.(Arg14del) pathogenic variant (cohort 1); patients diagnosed with, or predisposed to, ACM (cohort 2); and DCM patients (cohort 3). We found that the allele frequency of the p.(Ser96Ala) polymorphism was similar across the general European–American population (control cohort, 40.3–42.2%) and the different cardiomyopathy cohorts (cohorts 1–3, 40.9–43.9%). Furthermore, the p.(Ser96Ala) polymorphism was not associated with life-threatening arrhythmias or heart failure-related events across various patient cohorts. We therefore conclude that there is a lack of evidence supporting the important role of the HRC p.(Ser96Ala) polymorphism as a modifier in cardiomyopathy, refuting previous findings. Further research is required to identify bona fide genomic predictors for the stratification of cardiomyopathy patients and their risk for life-threatening outcomes.

Objective: Cryoballoon (CB) and laser-balloon (LB) catheter ablation (CA) has been demonstrated to achieve durable and effective pulmonary vein isolation (PVI). Only one head-to-head comparison with an intermittent rhythm monitor strategy is currently available. The aim of this study was to compare acute and long-term outcomes of CB and LB atrial fibrillation ablation procedures, by using a continuous rhythm monitoring strategy. Methods: This was a prospective two-arm nonrandomized propensity-matched observational trial that compared the outcomes of atrial fibrillation (AF) ablation using LB and CB techniques. To evaluate AF recurrences, an implantable cardiac monitor (ICM) was implanted before hospital discharge to detect atrial tachyarrhythmia (ATA) recurrences. Results: A total of 110 propensity-matched patients undergoing AF ablation with an LB (n = 55) or with a CB system (n = 55) were enrolled (paroxysmal AF 57.3%). Procedural time (LB: 87 [73–104] vs. CB 90 [70–130] min; p = 0.264) and fluoroscopy time did not differ. No differences in ATA recurrences were observed at 12 months (LB–30.9% vs. CB–29.1% and LB–45.5% vs. CB–38.2%; log-rank 0.539). As for AF burden, the 12-month median was 0 [0-1] vs. 0 [0-3]% (p = 0.127) in the LB and CB groups, respectively. When considering only PeAF patients, the median 12-month ATA burden was 26 [18.5-40.5] vs. 29 [26-35]% (p = 0.919) for the LB and CB patients, respectively. Conclusion: In a propensity-matched cohort undergoing AF ablation, arrhythmia outcomes assessed by continuous rhythm monitoring did not differ between LB and CB, with an overall low ATA burden. The only predictor of recurrences was persistent AF. There was no difference in procedure or fluoroscopy time.

Abstract Aims End‐stage heart failure necessitating evaluation for heart transplantation is increasingly recognized in arrhythmogenic right ventricular cardiomyopathy (ARVC). These patients present unique challenges in pre‐transplant and peri‐transplant management given their predominantly right ventricular (RV) failure and propensity for ventricular arrhythmias. We sought to utilize a tertiary ARVC referral and heart transplant centre experience to describe management of a series of patients with ARVC undergoing heart transplantation at our centre. Methods and results We queried the Johns Hopkins ARVC Registry for all patients who underwent heart transplantation and further studied the subset undergoing transplantation at the Johns Hopkins Hospital. Patient demographics, clinical characteristics, and pre‐transplant clinical course were obtained from the registry and electronic medical records. Of the 532 patients in the ARVC Registry, 63 (12%) underwent heart transplantation. Nine (six male) of these patients both had known ARVC prior to transplant and were transplanted at Johns Hopkins Hospital between 2006 and 2020 at a mean age of 42 ± 14 years old. Pathogenic ARVC genetic variants were identified in six (67%) patients, all of whom had variants in the plakophilin‐2 (PKP2) gene. RV failure was universal with median right atrial to pulmonary capillary wedge pressure (RA/PCWP) ratio of 1.4 [interquartile range (IQR) 1.2–1.5] and median right ventricular stroke work index (RVSWI) of 0 g·m/m2/beat (IQR 0–0.3). Six had a history of catheter ablation for ventricular arrhythmia with five of the six having at least three ablations. Transplant evaluation was initiated an average of 344 ± 407 days after first developing heart failure symptoms. The most common bridge to transplant support included inotropes (n = 3) and extracorporeal membrane oxygenation (ECMO) (n = 2). Contraindication to inotropes or mechanical support was common due to ventricular arrhythmia and RV predominant cardiomyopathy. Conclusions Heart transplantation is a curative treatment for ARVC, but due to frequent ventricular arrhythmias and RV predominant pathology, patients require unique considerations in regard to timing of evaluation, haemodynamic support options, and wait listing qualification.

Abstract Aims Heart failure is an increasingly recognized later stage manifestation of arrhythmogenic right ventricular cardiomyopathy (ARVC) that can require heart transplantation (HT) to appropriately treat. We aimed to study contemporary ARVC HT outcomes in a national registry. Methods and results The United Network for Organ Sharing registry was queried for HT recipients from 1/1994 through 2/2020. ARVC patients were compared with non‐ARVC dilated, restrictive, and hypertrophic cardiomyopathy HT patients (HT for ischaemic and valvular disease was excluded from analysis). Post‐HT survival was assessed using Kaplan–Meier estimates. A total of 189 of 252 (75%) waitlisted ARVC patients (median age 48 years, 65% male) underwent HT, representing 0.3% of the total 65 559 HT during the study time period. Annual frequency of HT for ARVC increased significantly over time. ARVC patients had less diabetes (5% vs. 17%, P

Background Heart failure (HF) has been increasing in prevalence, and a need exists for biomarkers with improved predictive and prognostic ability. GDF‐15 (growth differentiation factor‐15) is a novel biomarker associated with HF mortality, but no serial studies of GDF‐15 have been conducted. This study aimed to investigate the association between GDF‐15 levels over time and the occurrence of ventricular arrhythmias, HF hospitalizations, and all‐cause mortality. Methods and Results We used a retrospective case–control design to analyze 148 patients with ischemic and nonischemic cardiomyopathies and primary prevention implantable cardioverter‐defibrillator (ICD) from the PROSe‐ICD (Prospective Observational Study of the ICD in Sudden Cardiac Death Prevention) cohort. Patients had blood drawn every 6 months and after each appropriate ICD therapy and were followed for a median follow‐up of 4.6 years, between 2005 to 2019. We compared serum GDF‐15 levels within ±90 days of an event among those with a ventricular tachycardia/fibrillation event requiring ICD therapies and those hospitalized for decompensated HF. A comparator/control group comprised patients with GDF‐15 levels available during 2‐year follow‐up periods without events. Median follow‐up was 4.6 years in the 148 patients studied (mean age 58±12, 27% women). The HF cohort had greater median GDF‐15 values within 90 days (1797 pg/mL) and 30 days (2039 pg/mL) compared with the control group (1062 pg/mL, both P

Background: There are limited data describing the experience of radiofrequency (RF) vs. cryoballoon (CB) ablation for atrial fibrillation (AF) among elderly patients in the United States. Methods: We conducted a retrospective analysis of patients ≥75 years of age undergoing index RF vs. CB ablation between January 2014 and May 2020 at our center. The choice of ablation technique was left to the operator's discretion. Major complications and efficacy, defined as freedom from any atrial tachyarrhythmia (ATA) lasting ≥30 s after one year of follow-up, were assessed in patients with index RF vs. CB ablation. Results: In our cohort of 186 patients, the median age was 78 (76–81) years, 54.8% were men, and 39.2% had persistent AF. The median CHA2DS2-VASc score was 4 (3–4), while the median duration of AF was 3 (1–7) years. The majority (n = 112, 60.2%) underwent RF ablation. The median procedure time was significantly lower in CB group (197 vs 226.5 min, p=

BackgroundSmartphone ownership and mobile app use are steadily increasing in individuals of diverse racial and ethnic backgrounds living in the United States. Growing adoption of technology creates a perfect opportunity for digital health interventions to increase access to health care. To successfully implement digital health interventions and engage users, intervention development should be guided by user input, which is best achieved by the process of co-design. Digital health interventions co-designed with the active engagement of users have the potential to increase the uptake of guideline recommendations, which can reduce morbidity and mortality and advance health equity. ObjectiveWe aimed to co-design a digital health intervention for patients with atrial fibrillation, the most common cardiac arrhythmia, with patient, caregiver, and clinician feedback and to describe our approach to human-centered design for building digital health interventions. MethodsWe conducted virtual meetings with patients with atrial fibrillation (n=8), their caregivers, and clinicians (n=8). We used the following 7 steps in our co-design process: step 1, a virtual meeting focused on defining challenges and empathizing with problems that are faced in daily life by individuals with atrial fibrillation and clinicians; step 2, a virtual meeting focused on ideation and brainstorming the top challenges identified during the first meeting; step 3, individualized onboarding of patients with an existing minimally viable version of the atrial fibrillation app; step 4, virtual prototyping of the top 3 ideas generated during ideation; step 5, further ranking by the study investigators and engineers of the ideas that were generated during ideation but were not chosen as top-3 solutions to be prototyped in step 4; step 6, ongoing engineering work to incorporate top-priority features in the app; and step 7, obtaining further feedback from patients and testing the atrial fibrillation digital health intervention in a pilot clinical study. ResultsThe top challenges identified by patients and caregivers included addressing risk factor modification, medication adherence, and guidance during atrial fibrillation episodes. Challenges identified by clinicians were complementary and included patient education, addressing modifiable atrial fibrillation risk factors, and remote atrial fibrillation episode management. Patients brainstormed more than 30 ideas to address the top challenges, and the clinicians generated more than 20 ideas. Ranking of the ideas informed several novel or modified features aligned with the Theory of Health Behavior Change, features that were geared toward risk factor modification; patient education; rhythm, symptom, and trigger correlation for remote atrial fibrillation management; and social support. ConclusionsWe co-designed an atrial fibrillation digital health intervention in partnership with patients, caregivers, and clinicians by virtually engaging in collaborative creation through the design process. We summarize our experience and describe a flexible approach to human-centered design for digital health intervention development that can guide innovative clinical investigators.

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a heritable progressive myocardial disorder that predisposes patients to ventricular arrhythmias and sudden cardiac death. Antiarrhythmic medications have an important role in reducing the frequency of ventricular arrhythmias and the morbidity associated with recurrent implantable cardioverter-defibrillator (ICD) shocks. Although several studies have examined the use of antiarrhythmic drugs in ARVC, these have been mostly retrospective in nature and inconsistent in their methodology, patient population and endpoints. Thus, current prescribing practices are largely based on expert opinion and extrapolation from other diseases. Herein, we discuss the major studies of the use of antiarrhythmics in ARVC, present the current approach employed at the Johns Hopkins Hospital and identify areas where further research is needed. Most notably, there is a great need for high-quality studies with consistent methodology and randomized controlled trial data into the use of antiarrhythmic drugs in ARVC. This would improve management of the condition and ensure antiarrhythmic prescribing is based on robust evidence.

Increasing evidence suggests that the “NACHT-LRR and PYD domain-containing protein 3” (NLRP3) inflammasome plays an important role in atherosclerotic cardiovascular disease (ASCVD). Recent preclinical evidence has suggested that the NLRP3 inflammasome may play a prominent role in the pathogenesis of atrial fibrillation (AF). As such, the therapies that have shown efficacy in reducing ASCVD events may also prove beneficial in AF. In this article, we review the findings that implicate the NLRP3 inflammasome in the pathogenesis of AF, discuss existing evidence behind the use of anti-inflammatory agents for AF, and discuss the future role that colchicine and other anti-inflammatory agents may play in the prevention and treatment of AF.

Abstract Background Left ventricular (LV) fibrofatty infiltration in arrhythmogenic right ventricular (RV) dysplasia/cardiomyopathy (ARVD/C) has been reported, however, detailed cardiovascular magnetic resonance (CMR) characteristics and association with outcomes are uncertain. We aim to describe LV findings on CMR in ARVD/C patients and their relationship with arrhythmic outcomes. Methods CMR of 73 subjects with ARVD/C according to the 2010 Task Force Criteria (TFC) were analyzed for LV involvement, defined as ≥ 1 of the following features: LV wall motion abnormality, LV late gadolinium enhancement (LGE), LV fat infiltration, or LV ejection fraction (LVEF)

BackgroundThe relationship between inflammation and corrected QT (QTc) interval prolongation is currently not well defined in patients with COVID-19.ObjectiveThis study aimed to assess the effect of marked interval changes in the inflammatory marker C-reactive protein (CRP) on QTc interval in patients hospitalized with COVID-19.MethodsIn this retrospective cohort study of hospitalized adult patients admitted with COVID-19 infection, we identified 85 patients who had markedly elevated CRP levels and serial measurements of an ECG and CRP during the same admission. We compared mean QTc interval duration, and other clinical and ECG characteristics between times when CRP values were high and low. We performed mixed-effects linear regression analysis to identify associations between CRP levels and QTc interval in univariable and adjusted models.ResultsMean age was 58 ± 16 years, of which 39% were women, 41% were Black, and 25% were White. On average, the QTc interval calculated via the Bazett formula was 15 ms higher when the CRP values were “high” vs. “low” [447 ms (IQR 427–472 ms) and 432 ms (IQR 412–452 ms), respectively]. A 100 mg/L increase in CRP was associated with a 1.5 ms increase in QTc interval [β coefficient 0.15, 95% CI (0.06–0.24). In a fully adjusted model for sociodemographic, ECG, and clinical factors, the association remained significant (β coefficient 0.14, 95% CI 0.05–0.23).ConclusionAn interval QTc interval prolongation is observed with a marked elevation in CRP levels in patients with COVID-19.

Background: An estimated 1 million patients require cardiac implantable electronic devices (CIEDs) but go without annually. This disparity exists in low-to-middle-income nations largely owing to the cost of CIED hardware. Humanitarian reuse of CIEDs has been shown to be safe and feasible. However, recent publications have raised concern that promotion of CIED reuse may foster a CIED “black market,” to the dismay of manufacturers, regulators, and clinicians alike. Objective: To determine if unregulated CIED sales for potential human use is a real issue by investigating unregulated public online CIED sale listings in the United States of America. Methods: An observational study was undertaken over 6 months using multiple internet search engines from May 1 to November 1, 2019. We cataloged usable CIEDs (still in packaging, manufactured

Our world is faced with a global pandemic that threatens to overwhelm many national health care systems for a prolonged period. Consequently, the elective long-term cardiac implantable electronic device (CIED) management of millions of patients is potentially compromised, raising the likelihood of patients experiencing major adverse events owing to loss of CIED therapy. This review gives practical guidance to health care providers to help promptly recognize the requirement for expert consultation for urgent interrogation and/or surgery in CIED patients.

A 24-year-old man with muscle cramps and a family history of sudden death presented with palpitations. Electrocardiography showed signs of left ventricular hypertrophy and nonsustained ventricular tachycardia, and imaging studies confirmed hypertrophic cardiomyopathy. Genetic testing revealed a novel FHL1 mutation associated with Emery-Dreifuss muscular dystrophy. An implantable cardioverter-defibrillator was placed. (Level of Difficulty: Advanced.)

We report a case of a woman with arrhythmogenic right ventricular cardiomyopathy (ARVC) who presented with severe right-sided heart failure and cardiac cirrhosis that mandated heart-liver transplantation. This case highlights an emerging sex-based difference in ARVC where female sex is associated with a higher risk of heart failure than in male patients with ARVC. (Level of Difficulty: Advanced.)

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiomyopathy characterized by fibrofatty infiltration of predominantly the right ventricular (RV) myocardium. Affected patients typically present as young adults with hemodynamically stable ventricular tachycardia, although pediatric cases are increasingly recognized. These young subjects often have a more severe phenotype with a high risk of sudden cardiac death (SCD) and progression toward heart failure. Diagnosis of ARVC is made by combining multiple sources of information as prescribed by the consensus-based Task Force Criteria. The description of Naxos disease, a fully penetrant autosomal recessive disorder that is associated with ARVC and a cutaneous phenotype of palmoplantar keratoderma and wooly hair facilitated the identification of the genetic cause of ARVC. At present, approximately 60% of patients are found to carry a pathogenic variant in one of five genes associated with the cardiac desmosome. The incomplete penetrance and variable expressivity of these variants however implies an important role for environmental factors, of which participation in endurance exercise is a strong risk factor. Since there currently is no definite cure for ARVC, disease management is directed toward symptom reduction, delay of disease progression, and prevention of SCD. This clinically focused review describes the spectrum of ARVC among children and adolescents, the genetic architecture underlying this disease, the cardio-cutaneous syndromes that led to its identification, and current diagnostic and therapeutic strategies in pediatric ARVC subjects.

Atrial fibrillation (AF) patients are at high risk of stroke, with the left atrial appendage (LAA) found to be the most common site of clot formation. Presence of left atrial (LA) fibrosis has also been associated with higher stroke risk. However, the mechanisms for increased stroke risk in patients with atrial fibrotic remodeling are poorly understood. We sought to explore these mechanisms using fluid dynamic analysis and to test the hypothesis that the presence of LA fibrosis leads to aberrant hemodynamics in the LA, contributing to increased stroke risk in AF patients. We retrospectively collected late-gadolinium-enhanced MRI (LGE-MRI) images of eight AF patients (four persistent and four paroxysmal) and reconstructed their 3D LA surfaces. Personalized computational fluid dynamic simulations were performed, and hemodynamics at the LA wall were quantified by wall shear stress (WSS, friction of blood), oscillatory shear index (OSI, temporal directional change of WSS), endothelial cell activation potential (ECAP, ratio of OSI and WSS), and relative residence time (RRT, residence time of blood near the LA wall). For each case, these hemodynamic metrics were compared between fibrotic and non-fibrotic portions of the wall. Our results showed that WSS was lower, and OSI, ECAP, and RRT was higher in the fibrotic region as compared to the non-fibrotic region, with ECAP (p = 0.001) and RRT (p = 0.002) having significant differences. Case-wise analysis showed that these differences in hemodynamics were statistically significant for seven cases. Furthermore, patients with higher fibrotic burden were exposed to larger regions of high ECAP, which represents regions of low WSS and high OSI. Consistently, high ECAP in the vicinity of the fibrotic wall suggest that local blood flow was slow and oscillating that represents aberrant hemodynamic conditions, thus enabling prothrombotic conditions for circulating blood. AF patients with high LA fibrotic burden had more prothrombotic regions, providing more sites for potential clot formation, thus increasing their risk of stroke.

Characterized by lack of evidence of structural heart disease or any secondary causes of atrial fibrillation (AF), “lone AF” is used to represent a unique subtype of AF among young individuals aged less than 60 years. Although the longstanding definition has been proposed for years, the diagnostic criteria for “lone AF” remain ambiguous. As more contributing factors causing AF are recognized gradually, the validity of the term “lone AF” is in question. Despite advances in the past few decades, the mechanism of AF remains poorly understood, particularly in the absence of other structural changes. It is generally accepted that three essential electrophysiological elements (trigger, substrate, and modulators) contribute to the initiation and maintenance of lone AF. In addition, the role of microRNAs and genomic variations in the pathogenesis of lone AF has been also gaining attention. Some changes in relevant biomarker levels have also been proven to correlate with lone AF. Accumulating insights into the pathogenesis of lone AF strongly suggest coexistent disorders in patients with lone AF. Consequently, the growing evidence of these numerous and diverse pathogenic mechanisms and factors related to lone AF inevitably raises the question of whether the term “lone AF” is a meaningful category. The classification of lone AF as a separate identity has not lead to any unique clinical management. In this review, we update knowledge of definition, mechanisms, genetics, biomarkers, and clinical management of “lone AF.” With this comprehensive review, we suggest that the term “lone AF” should be abandoned for its futility. Key Words: lone atrial fibrillation, mechanism, genetics, biomarker, clinical management

Abstract Background: Recent studies suggest that left atrial (LA) late gadolinium enhancement (LGE) can quantify the underlying tissue remodeling that harbors atrial fibrillation (AF). However, quantification of LA-LGE requires labor-intensive magnetic resonance imaging acquisition and postprocessing at experienced centers. LA intra-atrial dyssynchrony assessment is an emerging imaging technique that predicts AF recurrence after catheter ablation. We hypothesized that 1) LA intra-atrial dyssynchrony is associated with LA-LGE in patients with AF and 2) LA intra-atrial dyssynchrony is greater in patients with persistent AF than in those with paroxysmal AF. Method: We conducted a cross-sectional study comparing LA intra-atrial dyssynchrony and LA-LGE in 146 patients with a history of AF (60.0 ± 10.0 years, 30.1% nonparoxysmal AF) who underwent pre-AF ablation cardiac magnetic resonance (CMR) in sinus rhythm. Using tissue-tracking CMR, we measured the LA longitudinal strain in two- and four-chamber views. We defined intra-atrial dyssynchrony as the standard deviation (SD) of the time to peak longitudinal strain (SD-TPS, in %) and the SD of the time to the peak pre-atrial contraction strain corrected by the cycle length (SD-TPSpreA, in %). We used the image intensity ratio (IIR) to quantify LA-LGE. Results: Intra-atrial dyssynchrony analysis took 5 ± 9 minutes per case. Multivariable analysis showed that LA intra-atrial dyssynchrony was independently associated with LA-LGE. In addition, LA intra-atrial dyssynchrony was significantly greater in patients with persistent AF than those with paroxysmal AF. In contrast, there was no significant difference in LA-LGE between patients with persistent and paroxysmal AF. LA intra-atrial dyssynchrony showed excellent reproducibility and its analysis was less time-consuming (5 ± 9 minutes) than the LA-LGE (60 ± 20 minutes). Conclusion: LA Intra-atrial dyssynchrony is a quick and reproducible index that is independently associated with LA-LGE to reflect the underlying tissue remodeling.

Background Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited condition associated with ventricular arrhythmias and myocardial dysfunction; however, limited data exist on identifying patients at highest risk. The purpose of the study was to determine whether measures of right ventricular (RV) dysfunction on echocardiogram including RV strain were predictive of structural disease progression in ARVC. Methods and Results A retrospective analysis of serial echocardiograms from 40 patients fulfilling 2010 task force criteria for ARVC was performed to assess structural progression defined by an increase in proximal RV outflow tract dimensions (parasternal short or long axis) or decrease in RV fractional area change. Echocardiograms were analyzed for RV free‐wall peak longitudinal systolic strain using 2‐dimensional speckle tracking. Risk of structural progression and 5‐year change in RV outflow tract measurements were compared with baseline RV strain. Of the 40 ARVC patients, 61% had structural progression with an increase in the mean parasternal short‐axis RV outflow tract dimension from 36.2 to 38.5 mm (P=0.022) and 68% by increase in parasternal long‐axis RV outflow tract dimension from 36.1 to 39.2 mm (P=0.001). RV fractional area change remained stable over time. Baseline RV strain was significantly associated with the risk of structural progression and 5‐year rate of change. Patients with an RV strain more positive than −20% had a higher risk (odds ratio: 18.4; 95% CI, 2.7–125.8; P=0.003) of structural progression. Conclusions RV free wall strain is associated with the rate of structural progression in patients with ARVC. It may be a useful marker in determining which patients require closer follow‐up and treatment.

Background Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is characterized by high arrhythmic burden and progressive heart failure, which can prompt referral for heart transplantation. Cardiopulmonary exercise testing (CPET) has an established role in risk stratification for advanced heart failure therapies, but has not been described in ARVC/D. This study sought to determine the safety and prognostic utility of CPET in patients with ARVC/D. Methods and Results Using the Johns Hopkins ARVC/D Registry, we examined patients with ARVC/D undergoing CPET. Baseline characteristics and transplant‐free survival were compared on the basis of peak oxygen consumption (pVO2) (≤14 or >14 mL/kg per minute) and ventilatory efficiency (Ve/VCO2 slope ≤34 or >34). Thirty‐eight patients underwent 50 CPETs. There were no sustained arrhythmic events. Twenty‐nine patients achieved a maximal test. Patients with pVO2 ≤14 mL/kg per minute were more often men (P=0.042) compared with patients with pVO2 >14 mL/kg per minute. Patients with Ve/VCO2 slope >34 tended to have more moderate/severe right ventricular dilation (7/9 [78%] versus 10/26 [38%]; P=0.060) and clinical heart failure (8/9 [89%] versus 13/26 [50%]; P=0.056) compared with patients with Ve/VCO2 slope ≤34. Patients who underwent heart transplantation were more likely to have clinical heart failure (10/10 [100%] versus 13/28 [46%]; P=0.003). Patients with Ve/VCO2 slope >34 had worse transplant‐free survival compared with patients with Ve/VCO2 slope ≤34 (n=35; hazard ratio, 6.57 [95% CI, 1.28–33.72]; log‐rank P=0.010), whereas transplant‐free survival was similar on the basis of pVO2 groups (n=29; hazard ratio, 3.38 [95% CI, 0.75–15.19]; log‐rank P=0.092). Conclusions CPET is safe to perform in patients with ARVC/D. Ve/VCO2 slope may be used for risk stratification and guide referral for heart transplantation in ARVC/D.

Background: Atrial arrhythmias are present in up to 20% of patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). Catheter ablation (CA) is an effective treatment for atrial arrhythmias in the general population. Data regarding CA for atrial arrhythmias in ARVC are scarce. Objective: To assess the safety and efficacy of CA for atrial arrhythmias in patients with ARVC. Methods: In this international collaborative effort, all patients with a definite diagnosis of ARVC undergoing CA for atrial fibrillation (AF), focal atrial tachycardia (AT), or cavotricuspid isthmus (CTI)-dependent atrial flutter (AFl) were extracted from twelve ARVC registries. Demographic, periprocedural, and long-term arrhythmic outcome data were collected. Results: Thirty-seven patients were enrolled in the study (age 50.2 ± 16.6 years, male 84%, CHA2DS2VASc 1 (1,2), HAS-BLED 0 (0–2)). The arrhythmia leading to CA was AF in 23 (62%), focal left AT in 5 (14%), and CTI-dependent AFl in 9 (24%). Acute procedural success was achieved in all procedures but one (n = 1 focal left AT; 97% acute success). The median follow-up period was 27 (13–67) months, and 96%, 74%, and 61% of patients undergoing AF ablation were free from any atrial arrhythmia recurrence after a single procedure at 6 months, 12 months, and last follow-up, respectively. After focal AT ablation, freedom from atrial arrhythmia recurrence was 80%, 80%, and 60% at 6 months, 12 months, and last follow-up, respectively. All patients undergoing CTI ablation were free from atrial arrhythmia recurrences at 6 months, with 89% single-procedural arrhythmic freedom at last follow-up. One major complication (2.7%; PV stenosis requiring PV stenting) occurred. Conclusions: CA is safe and effective in managing atrial arrhythmias in patients with ARVC, with success rates comparable to the general population.

Abstract Background Regional right ventricular (RV) dysfunction is the hallmark of Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy (ARVD/C), but is currently only qualitatively evaluated in the clinical setting. Feature Tracking Cardiovascular Magnetic Resonance (FT-CMR) is a novel quantitative method that uses cine CMR to calculate strain values. However, most prior FT-CMR studies in ARVD/C have focused on global RV strain using different software methods, complicating implementation of FT-CMR in clinical practice. We aimed to assess the clinical value of global and regional strain using FT-CMR in ARVD/C and to determine differences between commercially available FT-CMR software packages. Methods We analyzed cine CMR images of 110 subjects (39 overt ARVD/C [mutation+/phenotype+], 40 preclinical ARVD/C [mutation+/phenotype-] and 31 control) for global and regional (subtricuspid, anterior, apical) RV strain in the horizontal longitudinal axis using four FT-CMR software methods (Multimodality Tissue Tracking, TomTec, Medis and Circle Cardiovascular Imaging). Intersoftware agreement was assessed using Bland Altman plots. Results For global strain, all methods showed reduced strain in overt ARVD/C patients compared to control subjects (p 0.275). For regional strain, overt ARVD/C patients showed reduced strain compared to control subjects in all segments which reached statistical significance in the subtricuspid region for all software methods (p

Background: Abnormalities on cardiac imaging (cardiac magnetic resonance imaging [CMR] or positron emission tomography [PET]), left ventricular ejection fraction (LVEF), and electrophysiology study (EPS) all predict ventricular arrhythmias (VA) in patients with cardiac sarcoidosis (CS). We sought to assess the utility of EPS in patients with CS and abnormal cardiac imaging, focusing on those with LVEF >35%. Methods: We identified all patients treated at our institution from 2000 to 2017 who: 1.) had probable or definite CS; 2.) had either late gadolinium enhancement (LGE) on CMR or abnormal 18-flourodeoxyglucose (FDG) uptake on PET, and 3.) had undergone EPS. The primary endpoint was VA during follow up. Results: Twenty five patients were included, of whom 10 (40%) had positive EPS. During a mean follow-up of 4.8 +/− 3.4 years, 11 (44%) patients had VA. The positive predictive value (PPV) of EPS for VA was 100% and the negative predictive value (NPV) of EPS for VA was 93%. Among 12 patients with LVEF >35% and no prior VA, the PPV of EPS for VA was 100% and the NPV of EPS for VA was 90%. Conclusion: EPS may help with risk stratification in patients with CS and abnormal imaging, especially those without conventional indications for ICD placement. Among patients with LVEF >35% and no history of prior VA, a negative EPS has good positive and negative predictive value for future VA events. Keywords: Cardiac sarcoidosis, Ventricular arrhythmia, Sudden cardiac death, Electrophysiology study, Implantable cardioverter defibrillator

Background Despite growing use of the subcutaneous implantable cardioverter‐defibrillator (S‐ICD), its clinical role in arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) patients remains undefined. We aim to elucidate the cardiac phenotype, implant characteristics, and long‐term efficacy regarding appropriate therapy and complications in ARVC/D patients with an S‐ICD implant. Methods and Results A transatlantic cohort of ARVC/D patients who underwent S‐ICD implantation was analyzed for clinical characteristics, S‐ICD therapy, and long‐term outcome including device‐related complications. The cohort included 29 patients (52% male, 76% probands, 59% with ARVC/D‐associated mutation, 59% primary prevention [no prior sustained ventricular arrhythmias], and 45% first‐generation S‐ICD devices). At implant, all inducible patients (27/29) had conversion of induced ventricular fibrillation. Two patients (7%) had superficial infections of the incision site that were treated conservatively. Over a median follow‐up of 3.16 years (interquartile range: 2.21–4.51 years), all episodes (6 patients, 4% per year) of sustained ventricular arrhythmias were appropriately detected and treated. Six patients (21%) experienced 39 inappropriate shocks, with 3 requiring device explantation. Oversensing of noncardiac signal (n=4; especially myopotentials) and cardiac signal (n=4) was the most frequent etiology. No lead or device dislodgement, infection, skin erosion, or explantation related to need for antitachycardia pacing was noted. Conclusions S‐ICD can effectively treat both induced and spontaneous ventricular arrhythmias in patients with ARVC/D. The rate of inappropriate shocks, although considerable, is comparable to that in ARVC/D patients treated with transvenous ICDs. When they occurred, inappropriate shocks were primarily due to cardiac and, uniquely, noncardiac oversensing. We suggest potential strategies for minimizing inappropriate therapy.

Physiological stressors, such as exercise, can precipitate sudden cardiac death or heart failure progression in patients with arrhythmogenic cardiomyopathy (ACM). Yet, whether and to what extent a highly prevalent and more elusive environmental factor, such as psychosocial stress (PSS), can also increase ACM disease progression is unexplored. Here, we first quantified perceived stress levels in patients with ACM and found these levels correlated with the extent of arrhythmias and cardiac dysfunction. To determine whether the observed correlation is due to causation, we inflicted PSS-via the resident-intruder (RI) paradigm—upon Desmoglein-2 mutant mice, a vigorously used mammalian model of ACM. We found that ACM mice succumbed to abnormally high in-trial, PSS mortality. Conversely, no sudden deaths occurred in wildtype (WT) counterparts. Desmoglein-2 mice that survived RI challenge manifested markedly worse cardiac dysfunction and remodeling, namely apoptosis and fibrosis. Furthermore, WT and ACM mice displayed similar behavior at baseline, but Desmoglein-2 mice exhibited heightened anxiety following RI-induced PSS. This outcome correlated with the worsening of cardiac phenotypes. Our mouse model demonstrates that in ACM-like subjects, PSS is incisive enough to deteriorate cardiac structure and function per se, i.e., in the absence of any pre-existing anxious behavior. Hence, PSS may represent a previously underappreciated risk factor in ACM disease penetrance.

Focal impulse and rotor mapping (FIRM) involves intracardiac detection and catheter ablation of re-entrant drivers (RDs), some of which may contribute to arrhythmia perpetuation in persistent atrial fibrillation (PsAF). Patient-specific computational models derived from late gadolinium-enhanced magnetic resonance imaging (LGE-MRI) has the potential to non-invasively identify all areas of the fibrotic substrate where RDs could potentially be sustained, including locations where RDs may not manifest during mapped AF episodes. The objective of this study was to carry out multi-modal assessment of the arrhythmogenic propensity of the fibrotic substrate in PsAF patients by comparing locations of RD-harboring regions found in simulations and detected by FIRM (RDsim and RDFIRM) and analyze implications for ablation strategies predicated on targeting RDs. For 11 PsAF patients who underwent pre-procedure LGE-MRI and FIRM-guided ablation, we retrospectively simulated AF in individualized atrial models, with geometry and fibrosis distribution reconstructed from pre-ablation LGE-MRI scans, and identified RDsim sites. Regions harboring RDsim and RDFIRM were compared. RDsim were found in 38 atrial regions (median [inter-quartile range (IQR)] = 4 [3; 4] per model). RDFIRM were identified and subsequently ablated in 24 atrial regions (2 [1; 3] per patient), which was significantly fewer than the number of RDsim-harboring regions in corresponding models (p < 0.05). Computational modeling predicted RDsim in 20 of 24 (83%) atrial regions identified as RDFIRM-harboring during clinical mapping. In a large number of cases, we uncovered RDsim-harboring regions in which RDFIRM were never observed (18/22 regions that differed between the two modalities; 82%); we termed such cases “latent” RDsim sites. During follow-up (230 [180; 326] days), AF recurrence occurred in 7/11 (64%) individuals. Interestingly, latent RDsim sites were observed in all seven computational models corresponding to patients who experienced recurrent AF (2 [2; 2] per patient); in contrast, latent RDsim sites were only discovered in two of four patients who were free from AF during follow-up (0.5 [0; 1.5] per patient; p < 0.05 vs. patients with AF recurrence). We conclude that substrate-based ablation based on computational modeling could improve outcomes.

Background Prior studies have shown a close link between exercise and development of arrhythmogenic right ventricular cardiomyopathy. How much exercise restriction reduces ventricular arrhythmia (VA), how genotype modifies its benefit, and whether it reduces risk sufficiently to defer implantable cardioverter‐defibrillator (ICD) placement in arrhythmogenic right ventricular cardiomyopathy are unknown. Methods and Results We interviewed 129 arrhythmogenic right ventricular cardiomyopathy patients (age: 34.0±14.8 years; male: 60%) with ICDs (36% primary prevention) about exercise participation. Exercise change was defined as annual exercise duration and dose in the 3 years before clinical presentation minus that after presentation. The primary outcome was appropriate ICD therapy for VA. During the 5.1 years (interquartile range: 2.7–10.8 years) after presentation, 74% (95/129) patients reduced exercise dose and 85 (66%) patients experienced the primary outcome. In multivariate analyses, top tertile reduction in exercise duration and dose were both associated with less VA (duration: hazard ratio: 0.23 [95% confidence interval, 0.07–0.81]; dose: hazard ratio: 0.14 [95% confidence interval, 0.04–0.44]). Greater reduction in exercise dose conferred greater reduction in VA (P=0.01 for trend). Patients without desmosomal mutations and those with primary‐prevention ICDs benefited more from exercise reduction (P=0.16 and P=0.06 for interaction); however, 58% (18/31) of athletes who reduced exercise dose by >80% still experienced VA. Conclusions Exercise restriction should be recommended to all arrhythmogenic right ventricular cardiomyopathy patients with ICDs. Patients who are “gene‐elusive” and those with primary‐prevention devices may particularly benefit. Exercise reduction is unlikely to reduce arrhythmia sufficiently in high‐risk patients to alter decision‐making regarding ICD implantation.

AIMS:Likely pathogenic/pathogenic variants in genes encoding desmosomal proteins play an important role in the pathophysiology of arrhythmogenic right ventricular cardiomyopathy (ARVC). However, for a substantial proportion of ARVC patients, the genetic substrate remains unknown. We hypothesized that plectin, a cytolinker protein encoded by the PLEC gene, could play a role in ARVC because it has been proposed to link the desmosomal protein desmoplakin to the cytoskeleton and therefore has a potential function in the desmosomal structure. METHODS:We screened PLEC in 359 ARVC patients and compared the frequency of rare coding PLEC variants (minor allele frequency [MAF]

BackgroundArrhythmogenic right ventricular dysplasia/cardiomyopathy is characterized by ventricular arrhythmias and sudden cardiac death. Once the diagnosis is established, risk stratification to determine whether implantable cardioverter‐defibrillator (ICD) placement is warranted is critical. Methods and ResultsThe cohort included 312 patients (163 men, age at presentation 33.6±13.9 years) with definite arrhythmogenic right ventricular dysplasia/cardiomyopathy who received an ICD. Over 8.8±7.33 years, 186 participants (60%) had appropriate ICD therapy and 58 (19%) had an intervention for ventricular fibrillation/flutter. Ventricular tachycardia at presentation (hazard ratio [HR]: 1.86; 95% confidence interval [CI], 1.38–2.49; P