<div><h4>Atrial electrofunctional predictors of incident atrial fibrillation in cardiac amyloidosis.</h4><i>Sinigiani G, De Michieli L, Porcari A, Zocchi C, ... Cappelli F, Cipriani A</i><br /><b>Background</b><br />Atrial fibrillation (AF) is common in patients with cardiac amyloidosis (CA) and is a significant risk factor for heart failure hospitalization and thromboembolic events.<br /><b>Objective</b><br />This study was designed to investigate the atrial electrofunctional predictors of incident AF in CA.<br /><b>Methods</b><br />A multicenter, observational study was conducted in 4 CA referral centers including sinus rhythm patients with light-chain (AL) and transthyretin (ATTR) CA undergoing electrocardiography and cardiac magnetic resonance imaging. The primary end point was new-onset AF occurrence.<br /><b>Results</b><br />Overall, 96 patients (AL-CA, n = 40; ATTR-CA, n = 56) were enrolled. During an 18-month median follow-up (Q1-Q3, 7-29 months), 30 patients (29%) had incident AF. Compared with those without AF, patients with AF were older (79 vs 73 years; P = .001). They more frequently had ATTR (87% vs 45%; P < .001); electrocardiographic interatrial block (IAB), either partial (47% vs 21%; P = .011) or advanced (17% vs 3%; P = .017); and lower left atrial ejection fraction (LAEF; 29% vs 41%; P = .004). Age (hazard ratio [HR], 1.059; 95% CI, 1.002-1.118; P = .042), any type of IAB (HR, 2.211; 95% CI, 1.03-4.75; P = .041), and LAEF (HR, 0.967; 95% CI, 0.936-0.998; P = .044) emerged as independent predictors of incident AF. Patients exhibiting any type of IAB, LAEF <40%, and age >78 years showed a cumulative incidence for AF of 40% at 12 months. This risk was significantly higher than that carried by 1 (8.5%) or none (7.6%) of these 3 risk factors.<br /><b>Conclusion</b><br />In patients with CA, older age, IAB on 12-lead electrocardiography, and reduced LAEF on cardiac magnetic resonance imaging are significant and independent predictors of incident AF. A closer screening for AF is advisable in CA patients carrying these features.<br /><br />Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.<br /><br /><small>Heart Rhythm: 01 Jun 2024; 21:725-732</small></div>

<div><h4>Biatrial arrhythmogenic substrate in patients with hypertrophic obstructive cardiomyopathy.</h4><i>Ramdat Misier NL, Amesz JH, Taverne YJHJ, Nguyen H, ... Brundel BJJM, de Groot NMS</i><br /><b>Background</b><br />Atrial fibrillation (AF) in patients with hypertrophic obstructive cardiomyopathy (HOCM) may be caused by a primary atrial myopathy. Whether HOCM-related atrial myopathy affects mainly electrophysiological properties of the left atrium (LA) or also the right atrium (RA) has never been investigated.<br /><b>Objective</b><br />The purpose of this study was to characterize atrial conduction and explore differences in the prevalence of conduction disorders, potential fractionation, and low-voltage areas (LVAs) between the RA and LA during sinus rhythm (SR) as indicators of potential arrhythmogenic areas.<br /><b>Methods</b><br />Intraoperative epicardial mapping of both atria during SR was performed in 15 HOCM patients (age 50 ± 12 years). Conduction delay (CD) and conductin block (CB), unipolar potential characteristics (voltages, fractionation), and LVA were quantified.<br /><b>Results</b><br />Conduction disorders and LVA were found scattered throughout both atria in all patients and did not differ between the RA and LA (CD: 2.9% [1.9%-3.6%] vs 2.6% [2.1%-6.4%], P = .541; CB: 1.7% [0.9%-3.1%] vs 1.5% [0.5%-2.8%], P = .600; LVA: 4.7% [1.6%-7.7%] vs 2.9% [2.1%-7.1%], P = .793). Compared to the RA, unipolar voltages of single potentials (SPs) and fractionated potentials (FPs) were higher in the LA (SP: P75 7.3 mV vs 10.9 mV; FP: P75 2.0 mV vs 3.7 mV). FP contained low-voltage components in only 18% of all LA sites compared to 36% of all RA sites.<br /><b>Conclusion</b><br />In patients with HOCM, conduction disorders, LVA, and FP are equally present in both atria, supporting the hypothesis of a primary atrial myopathy. Conceptually, the presence of a biatrial substrate and high-voltage FP may contribute to failure of ablative therapy of atrial tachyarrhythmias in this population.<br /><br />Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.<br /><br /><small>Heart Rhythm: 01 Jun 2024; 21:819-827</small></div>