Carina Blomström-Lundqvist

Background and Aims: MODULAR ATP is an ongoing trial assessing the efficacy of a subcutaneous implantable cardioverter defibrillator (S-ICD) in communication with a leadless pacemaker (LP) that can deliver bradycardia pacing and antitachycardia pacing. The objective of this study was to assess safety and pacing performance of the investigational LP. Methods: The study enrolled patients with an ICD indication and at high risk for monomorphic ventricular tachycardia. Pacemaker dependent patients were excluded. Primary safety endpoint 2 was the percentage of patients free from major LP-related complications at 12 months. The secondary effectiveness endpoint assessed the rate response performance of the LP under workload. Parameters related to the pacing performance were also measured. Results: In 297 patients, the mean age was 59±12 years, the mean left ventricular ejection fraction was 35.3±13.1%, and 17.5% were female. LP implant was attempted in 286 patients and was successful in 100%. The major LP-related complication free rate at 12 months was 97.2% (one-sided 97.5% LCL 94.5%), surpassing the performance goal of 81%. There were no LP-related complications following Implant. For the secondary effectiveness endpoint, the slope of the normalized sensor rate versus the normalized workload was 0.96 (95% LCL 0.91, 95% UCL 1.02), within the performance goal range of 0.65-1.35. At 12 months, 96.8% of patients had a pacing capture threshold ≤ 2V @ 0.4ms pulse width. Conclusions: The performance of the modular pacing-defibrillator system at one year demonstrated a low complication rate and reliable pacing functionality.

The aim of the AFA-ARC (Atrial Fibrillation Ablation Academic Research Consortium) initiative is to reexamine trial design and the safety and effectiveness end points for pivotal clinical trials evaluating catheter ablation for the treatment of symptomatic atrial fibrillation to provide meaningful and interpretable data to support regulatory decision-making. Beginning in July 2024, a group of international experts began meeting regularly both virtually together and separately in working groups (group 1 effectiveness end points; group 2 safety end points; and group 3 trial design and report forms), with one in-person meeting held in April 2025, and revisions of draft proposals from January 2025 to February 2026. The Food and Drug Administration Office of Cardiovascular Devices at the Center for Devices and Radiological Health provided input throughout the revision and proposal process. A patient advocate participated in the in-person meeting and during the revision phase. Heart Rhythm Society leadership was involved throughout the process and in the revision phase. Industry representatives were sent drafts of the proposed manuscripts during the revision phase before submission. The result of this process was the creation of a combined document to reexamine trial design and the safety and effectiveness end points for pivotal clinical trials evaluating catheter ablation of atrial fibrillation. This document represents contributions from each of the 3 Working Groups. The Heart Rhythm Society endorsed this document. This AFA-ARC document proposes revised effectiveness and safety end points, study design, and report forms for studies evaluating AF ablation in patients with symptomatic paroxysmal, persistent, or longstanding persistent AF.

BACKGROUND: MODULAR antitachycardia pacing (ATP), a multicenter, international trial, assesses a modular cardiac rhythm management system: a subcutaneous implantable cardioverter defibrillator in wireless communication with a leadless pacemaker (LP) capable of pace-terminating ventricular tachycardia. METHODS: Enrolees had one or more clinical risk factors for ventricular tachycardia and did not require chronic pacing. Complications included prespecified major LP system- and procedure-related complications, and any complication related to the LP, subcutaneous implantable cardioverter defibrillator, implantation, or study protocol. Survival analysis was performed to identify complication-free rates, therapy delivery, and all-cause mortality. RESULTS: The 297 patients enrolled had an ejection fraction of 35±13%, 43% secondary prevention indications, and 59% with prior ventricular arrhythmias. Of 286 patients undergoing LP implantation (100% success), 251 patients completed 12-month follow-up. Mortality rate was 6%, with none related to the implant procedure. Median follow-up duration was 23.4 months (interquartile range, 17.9–28.1). The LP major complication-free rate was 97.2%, exceeding the performance goal. The overall LP+ subcutaneous implantable cardioverter defibrillator system-related complication-free rate was 88.5%. Appropriate tachyarrhythmia-therapy (ATP+shock) rates were 14.4%, and appropriate shock rates were 8.5%. Inappropriate total tachyarrhythmia therapy was 9.5% of which 8.5% were shocks. ATP was 67.3% successful in terminating ventricular arrhythmia episodes and accelerated ventricular arrhythmias in 10.1% of episodes. Overall therapy burden (ATP+shock) was 96/100 patient-years, of which 44/100 patient-years was for shock delivery. CONCLUSIONS: One-year outcomes of the first modular pacing-defibrillator system reveal low system and LP complication rates and good ATP efficacy rates, suggesting that the modular cardiac rhythm management is a viable alternative to single-chamber implantable cardioverter defibrillators using low-energy pacing capability without the need for transvenous leads. CLINICAL TRIAL REGISTRATION: URL: https://clinicaltrials.gov/ ; Unique identifier: NCT04798768.

Aims: Ventricular tachyarrhythmias (VT/VF) are common among patients with prior myocardial infarction (MI). MANTRA-VT trial was designed to compare the efficacy and safety of early substrate-based radiofrequency catheter ablation (RFCA) to antiarrhythmic drug (AAD) therapy for ventricular tachyarrhythmias. Methods and results: We randomly assigned 58 AAD naïve post MI patients with implantable cardioverter defibrillator (ICD) and at least one documented VT/VF episode after the device implantation to an initial treatment strategy of substrate-based RFCA or AAD therapy. The primary endpoint was cumulative number of ventricular tachyarrhythmias (VT/VF burden) at 12 months. The secondary endpoints included all-cause mortality, hospitalization, adverse events, and VT/VF burden at 24 months. Analyses were performed on an intention-to-treat basis. The median number of VT/VF episodes at 12 months was zero in both the RFCA (range 0–3) and the AAD group (range 0–23) (P = 0.454), whereas the rate of appropriate ICD shocks was 7% and 30% in the RFCA and the AAD groups (P = 0.026), respectively. During the extended follow-up, 82% of the patients in the RFCA group and 63% in the AAD group had no ICD therapies (P = 0.012). There was no significant difference between the groups in total mortality (HR 1.02, 95% CI 0.20–5.11, P = 0.86) and hospitalization (HR 1.35, 95% CI 0.36–5.09. P = 0.66) at 24 months. Therapy-related adverse events occurred in 3.6% and 16.7% of the patients in the RFCA and the AAD groups (P = 0.10), respectively. Conclusion: Early substrate-based RFCA was associated with reduced risk of ICD therapies, but with no meaningful difference in VT/VF burden, mortality, hospitalization, and adverse events.

Ablation of atrial fibrillation can restore normal heart rhythm, but its effect on clinical outcomes is uncertain. To determine the effect of ablation on ischemic stroke at more than 30 days (primary outcome). Search of 9 databases without language restrictions from 1 January 1987 to 13 September 2024, and bridge search of 2 databases to 1 May 2025. Randomized controlled trials of catheter or surgical ablation versus no ablation that had at least 1 month of follow-up and reported stroke and/or mortality. Dual independent data extraction and risk-of-bias assessment. Compared with medical therapy, catheter ablation reduced risks for ischemic stroke after 30 days (relative risk [RR], 0.63 [95% CI, 0.43 to 0.92]), mortality (RR, 0.73 [CI, 0.60 to 0.88]), and heart failure (HF) hospitalization (RR, 0.68 [CI, 0.55 to 0.85]). However, catheter ablation increased the RR for ischemic stroke at or before 30 days (6.81 [CI, 1.56 to 29.8]) such that the RRs were 0.77 (CI, 0.55 to 1.09) for any ischemic stroke and 0.77 (CI, 0.57 to 1.05) for all strokes. Surgical ablation reduced the RRs for ischemic stroke (0.54 [CI, 0.34 to 0.86]) and stroke from any cause (0.54 [CI, 0.35 to 0.82]) but had uncertain benefit for other outcomes; RRs were 0.63 (CI, 0.37 to 1.06) for ischemic stroke after 30 days, 0.90 (CI, 0.70 to 1.15) for mortality, and 0.90 (CI, 0.60 to 1.35) for HF hospitalization. Clinical heterogeneity of trials, lack of participant-level data, and inclusion of unblinded trials. Catheter ablation reduced the risks for ischemic stroke at more than 30 days, mortality, and HF hospitalization. Surgical ablation had uncertain benefit, except for stroke. National Center for Advancing Translational Sciences of the National Institutes of Health (Awards TL1TR002344 and UL1TR002345). (PROSPERO: CRD42023409751).

The European Heart Rhythm Association Practical Compendium of Anti-arrhythmic Drugs (AADs) offers advice on these drugs, focusing on their clinical use and the global impact of cardiac arrhythmias. This document aims to provide practical instructions to clinicians in arrhythmia management through pharmacological strategies. The compendium highlights persistent challenges in arrhythmia treatment, including clinical constraints, procedural risks, and the complexity of certain arrhythmias. Notably, atrial fibrillation is highly prevalent, and the demand for invasive treatment often surpasses the capacity of existing healthcare systems. As a result, pharmacological management remains essential. This is particularly relevant for patients with cardiac implantable electronic devices or channelopathies, where ablation is often not a suitable option. Anti-arrhythmic drugs play a pivotal role in these scenarios. The compendium introduces the ABC framework for AAD therapy: A (Appropriate therapy), for patients in whom AADs are the best therapeutic option; B (Backup therapy), as adjunctive treatment to invasive procedures, such as catheter ablation; and C (Complementary therapy), in combination with other therapies. The document provides detailed insights into the mechanisms of action, efficacy, safety profiles, and drug interactions of each class of AADs. Additionally, the compendium covers practical considerations, including initiation, combination strategies, monitoring, follow-up, special populations, and adverse effect management, with an emphasis on pro-arrhythmia risk mitigation. It also explores the integration of AADs with other therapeutic modalities, promoting a synergistic approach to optimize patient outcomes. In summary, this compendium serves as an indispensable resource for clinicians, offering practical advice and evidence-based insights to navigate the complexities of arrhythmia management effectively.

Atrial fibrillation (AF) is one of the most common cardiac diseases and a complicating comorbidity for multiple associated diseases. Many clinical decisions regarding AF are currently based on the binary recognition of AF being present or absent with the categorical appraisal of AF as continued or intermittent. Assessment of AF in clinical trials is largely limited to the time to (first) detection of an AF episode. Substantial evidence shows, however, that the quantitative characteristic of intermittent AF has a relevant impact on symptoms, onset, and progression of AF and AF-related outcomes, including mortality. Atrial fibrillation burden is increasingly recognized as a suitable quantitative measure of intermittent AF that provides an estimate of risk attributable to AF, the efficacy of antiarrhythmic treatment, and the need for oral anticoagulation. However, the diversity of assessment methods and the lack of a consistent definition of AF burden prevent a wider clinical applicability and validation of actionable thresholds of AF burden. To facilitate progress in this field, the AF burden Consensus Group, an international and multidisciplinary collaboration, proposes a unified definition of AF burden. Based on current evidence and using a modified Delphi technique, consensus statements were attained on the four main areas describing AF burden: Defining the characteristics of AF burden, the recording principles, the clinical relevance in major clinical conditions, and implementation as an outcome in the clinic and in clinical trials. According to this consensus, AF burden is defined as the proportion of time spent in AF expressed as a percentage of the recording time, undertaken during a specified monitoring duration. A pivotal requirement for validity and comparability of AF burden assessment is a continuous or near-continuous duration of monitoring that needs to be reported together with the AF burden assessment. This proposed unified definition of AF burden applies independent of comorbidities and outcomes. However, the disease-specific actionable thresholds of AF burden need to be defined according to the targeted clinical outcomes in specific populations. The duration of the longest episode of uninterrupted AF expressed as a time duration should also be reported when appropriate. A unified definition of AF burden will allow for comparability of clinical study data to expand evidence and to establish actionable thresholds of AF burden in various clinical conditions. This proposed definition of AF burden will support risk evaluation and clinical treatment decisions in AF-related disease. It will further promote the development of clinical trials studying the clinical relevance of intermittent AF. A unified approach on AF burden will finally inform the technology development of heart rhythm monitoring towards validated technology to meet clinical needs.

Background: Short and rare episodes of atrial fibrillation (AF) are commonly detected using implanted devices (device‐detected AF) in patients with prior stroke or transient ischemic attack (TIA). The effectiveness and safety of oral anticoagulation in patients with prior stroke or TIA and device‐detected AF but with no ECG‐documented AF is unclear. Methods and Results: This prespecified analysis of the NOAH‐AFNET 6 (Non‐Vitamin K Antagonist Oral Anticoagulants in Patients With Atrial High Rate Episodes) trial with post hoc elements assessed the effect of oral anticoagulation in patients with device‐detected AF with and without a prior stroke or TIA in the randomized, double‐blind, double‐dummy NOAH‐AFNET 6 trial. Outcomes were stroke, systemic embolism, and cardiovascular death (primary outcome) and major bleeding and death (safety outcome). A prior stroke or TIA was found in 253 patients with device‐detected AF randomized in the NOAH‐AFNET 6 (mean age, 78 years; 36.4% women). There was no treatment interaction with prior stroke or TIA for any of the primary and secondary time‐to‐event outcomes. In patients with a prior stroke or TIA, 14 out of 122 patients experienced a primary outcome event with anticoagulation (5.7% per patient‐year). Without anticoagulation, there were 16 out of 131 patients with an event (6.3% per patient‐year). The rate of stroke was lower than expected (anticoagulation: 4 out of 122 [1.6% per patient‐year]; no anticoagulation: 6 out of 131 [2.3% per patient‐year]). Numerically, there were more major bleeding events with anticoagulation in patients with prior stroke or TIA (8 out of 122 patients) than without anticoagulation (2 out of 131 patients). Conclusions: Anticoagulation appears to have ambiguous effects in patients with device‐detected AF and a prior stroke or TIA in this hypothesis‐generating analysis of the NOAH‐AFNET 6 in the absence of ECG‐documented AF, partially due to a low rate of stroke without anticoagulation.