Anticoagulation in atrial fibrillation and implantable cardioverter defibrillator implantation in arrhythmogenic right ventricular cardiomyopathy: need for improving patient selection

For the podcast associated with this article, please visit https://academic.oup.com/eurheartj/pages/Podcasts. This issue contains two contributions from our Year in Cardiovascular Medicine 2023 series: ‘The year in cardiovascular medicine 2023: the top 10 papers in dyslipidaemias’ by EHJ Editors Lale Tokgozoglu, Carl Orringer, and Alberico Catapano1, as well as ‘The year in cardiovascular medicine 2023: the top 10 papers in heart failure and cardiomyopathies’ by EHJ Editors Johann Bauersachs, Rudolf A. de Boer, and Shelley Zieroth.2 Articles in this series highlight and summarize key papers from the last year. The issue continues with a focus on arrhythmias, which opens with the Fast Track Congress manuscript ‘Atrial fibrillation progression after cryoablation vs. radiofrequency ablation: the CIRCA-DOSE trial’ by Jason Andrade from the University of British Columbia in Vancouver, Canada, and colleagues.3 The authors note that atrial fibrillation (AF) is a chronic progressive disorder.4–9 Persistent forms of AF are associated with increased rates of thrombo-embolism, heart failure, and death. Catheter ablation modifies the pathogenic mechanism of AF progression. A total of 346 patients with drug-refractory paroxysmal AF were enrolled and randomly assigned to contact force-guided RF ablation (CF-RF ablation), 4-min cryoballoon ablation (CRYO-4), or 2-min cryoballoon ablation (CRYO-2). Implantable cardiac monitors placed at study entry were used for follow-up. The main outcome was the first episode of persistent atrial tachyarrhythmia. Secondary outcomes included atrial tachyarrhythmia recurrence and arrhythmia burden on the implantable monitor. At a median of 944 days, none of 115 patients randomly assigned to CF-RF, 8 of 115 patients assigned to CRYO-4, and 5 of 116 patients assigned to CRYO-2 experienced an episode of persistent atrial tachyarrhythmia (P = .03). A documented recurrence of any atrial tachyarrhythmia ≥30 s occurred in 56, 54, and 63% of patients, respectively; P = .65. Compared with that of the pre-ablation monitoring period, AF burden was reduced by a median of 99.5% with CF-RF, 99.9% with CRYO-4, and 99.1% with CRYO-2 (Figure 1). Atrial fibrillation progression after cryoablation vs. radiofrequency ablation. AF, atrial fibrillation; AFL, atrial flutter; AT, atrial tachycardia; PVI, pulmonary vein isolation; CF-RF, standard RF ablation guided by tissue contact force; CRYO-4, 4-min cryoballoon ablation duration; CRYO-2, 2-min cryoballoon ablation duration.3 The authors conclude that catheter ablation of paroxysmal AF using radiofrequency energy is associated with fewer patients developing persistent AF on follow-up as compared with cryoablation. The contribution is accompanied by an Editorial by Hadi Younes, Nassir Marrouche, and Swati Rao from Tulane University School of Medicine in New Orleans, LA, USA.10 The authors conclude by noting that this study raises many questions and calls for a meticulous investigation to determine which patient populations are more prone to AF progression using each energy delivery source. Exploring pulse-field ablation is another crucial aspect. Furthermore, it is important that these results undergo validation in a prospective trial powered for AF progression. Oral anticoagulants play a key role in the management of AF.11–15 In a Clinical Research article entitled ‘Oral anticoagulation after atrial fibrillation catheter ablation: benefits and risks’, Koshiro Kanaoka from the National Cerebral and Cardiovascular Center in Osaka, Japan, and colleagues indicate that few recent large-scale studies have evaluated the risks and benefits of continuing oral anticoagulant (OAC) therapy after catheter ablation (CA) for AF.16 This retrospective study evaluated the status of continuation of OAC therapy and the association between continuation of OAC therapy and thrombo-embolic and bleeding events according to the CHADS2 score. It included data from the Japanese nationwide administrative claims database of patients who underwent CA for AF between April 2014 and March 2021. Patients without AF recurrence assessed by administrative data of the treatment modalities were divided into two groups according to continuation of OAC therapy 6 months after the index CA. The primary outcomes were thrombo-embolism and major bleeding after a landmark period of 6 months. After inverse probability of treatment weighting analysis, the association between OAC continuation and outcomes was determined according to the CHADS2 score. Among ∼231 000 patients included, 71% continued OAC therapy at 6 months. In the CHADS2 score ≤1 group, the hazard ratio (HR) of the continued OAC group was .86 (P = .06) for thrombo-embolism and was 1.51 (P < .001) for major bleeding. In the CHADS2 score ≥3 group, the HR of the continued OAC group was .61 (P = .001) for thrombo-embolism and 1.05 (P = .81) for major bleeding. Kanaoka and colleagues conclude that this observational study suggests that the benefits and risks of continuing OAC therapy after CA for AF differ based on the patient’s CHADS2 score. The risk of major bleeding due to OAC continuation seems to outweigh the risk reduction of thrombo-embolism in patients with lower thrombo-embolic risk. The contribution is accompanied by an Editorial by Stephen Brienesse from the Royal Prince Alfred Hospital in Camperdown, Australia, Ben Freedman from the Heart Research Institute in Sydney, Australia, and Rod Passman from Northwestern University Feinberg School of Medicine in Chicago, IL, USA.17 The authors note that further work is required in understanding the critical threshold of AF burden in low risk patients with paroxysmal AF to tip the scales in determining eligibility for long-term OAC. The results of pending trials including OCEAN and REACT-AF are eagerly anticipated in this regard. For now, the decision to continue OAC following catheter ablation for AF remains firmly based on determining stroke risk using CHADS2 or CHA2DS2-VASc scores. Implantable cardioverter defibrillators (ICDs) are critical for preventing sudden cardiac death (SCD) in arrhythmogenic right ventricular cardiomyopathy (ARVC).18–21 In a Clinical Research article entitled ‘Implantable cardioverter defibrillator use in arrhythmogenic right ventricular cardiomyopathy in North America and Europe’, Richard Carrick from Johns Hopkins University in Baltimore, MD, USA, and colleagues aim to identify cross-continental differences in utilization of primary prevention ICDs and survival free from sustained ventricular arrhythmia (VA) in ARVC.22 This was a retrospective analysis of ARVC patients without prior VA enrolled in clinical registries from 11 countries throughout Europe and North America. Patients were classified according to whether they received treatment in North America or Europe, and were further stratified by baseline predicted VA risk into low- (<10%/5 years), intermediate- (10%–25%/5 years), and high-risk (>25%/5 years) groups. Differences in ICD implantation and survival free from sustained VA events (including appropriate ICD therapy) were assessed. A total of 1098 patients were followed for a median of 5.1 years; 50% received a primary prevention ICD, 26% experienced a first VA event. After adjusting for baseline risk factors, North Americans were more than three times as likely to receive ICDs (Hazard ratio 3.1). Of note, North Americans had mildly, although significantly, increased risk for incident sustained VA (HR 1.4). North Americans without ICDs were at significantly higher risk for incident sustained VA (Hazard ratio 2.1) than Europeans (Figure 2). In this multi-national cohort of arrhythmogenic right ventricular cardiomyopathy patients, North American patients were much more likely to receive implantable cardioverter defibrillator (ICDs) than European patients across all risk strata. Differences in rates of sustained ventricular arrhythmia (VA) between North America and Europe were limited to patients identified as high risk by baseline risk estimates.22 The authors conclude that North American ARVC patients are substantially more likely than Europeans to receive primary prevention ICDs across all arrhythmic risk strata. A lower rate of ICD implantation in Europe is not associated with a higher rate of VA events in those without ICDs. This manuscript is accompanied by an Editorial by Perry Elliott from University College London and St. Bartholomew’s Hospital in London, UK.23 Elliott highlights that this study once again shines a light on potential differences in transatlantic philosophies regarding sudden death prevention but there are, perhaps, more important take-home messages from this paper. First, the study confirms the high annual incidence of VA in patients with ARVC and underlines the importance of a systematic approach to risk prediction using currently available risk tools. Secondly, a more conservative approach to ICD implantation in individuals at low risk is not associated with a higher risk of death, a fact that should be considered in shared decision-making with patients. The task for the future will be to increase the fidelity of outcome models by combining sophisticated clinical phenotyping that takes into account the temporal evolution of disease, genetic data, and potential disease modifiers including exercise intensity. The issue is also complemented by two Discussion Forum contributions. In a commentary entitled ‘Randomized controlled trials are not always the solution’, Sara Finocchietti from the North American Science Associates (NAMSA) in Chasse-sur-Rhône, France and colleagues comment on the recent publication ‘Quality and transparency of evidence for implantable cardiovascular medical devices assessed by the CORE-MD consortium’ by George C.M. Siontis from the University of Bern in Switzerland.24,25 Siontis et al. respond in a separate comment.26 The editors hope that this issue of the European Heart Journal will be of interest to its readers. Dr. Crea reports speaker fees from Abbott, Amgen, Astra Zeneca, BMS, Chiesi, Daiichi Sankyo, Menarini outside the submitted work. With thanks to Amelia Meier-Batschelet, Johanna Huggler, and Martin Meyer for help with compilation of this article.

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