Heart rhythm最新文献

{"title":"Catheter ablation vs antiarrhythmic therapy for atrial fibrillation in heart failure with preserved ejection fraction.","authors":"Marisa R DeLuca, Bilal Ali, Yasir Tarabichi, Beni R Verma, Saima Karim","doi":"10.1016/j.hrthm.2024.10.034","DOIUrl":"10.1016/j.hrthm.2024.10.034","url":null,"abstract":"<p><strong>Background: </strong>Clinical outcomes of patients with atrial fibrillation (AF) and heart failure with preserved ejection fraction (HFpEF) treated with catheter ablation (CA) vs antiarrhythmic therapy (AAT) are not well known.</p><p><strong>Objective: </strong>This study compared morbidity and mortality of patients with AF and HFpEF treated with CA vs AAT.</p><p><strong>Methods: </strong>AF and HFpEF patients from January 2017 to June 2023 were identified in TriNetX, a large global population-based database. Patients with prior diagnosis of heart failure with reduced ejection fraction (HFrEF) or crossover between AAT and CA were excluded. Baseline characteristics including age, sex, body mass index, type of AF, comorbidities, and cardiovascular medications were compared. The 2 groups were 1:1 propensity score matched for outcomes analysis. All-cause mortality, cerebrovascular accident/transient ischemic attack, and acute heart failure were compared with Kaplan-Meier curves.</p><p><strong>Results: </strong>Patients treated with CA (n = 1959) and AAT (n = 7689) were 1:1 propensity score matched, yielding 3632 patients with no significant differences in baseline characteristics. Compared with AAT, CA was associated with decreased mortality (9.2% vs 20.5%; hazard ratio [HR], 0.431; 95% confidence interval [CI], 0.359-0.518; P < .001). In addition, CA was associated with reduced HFpEF (HR, 0.638; 95% CI, 0.550-0.741; P < .001) and acute HFrEF (HR, 0.645; 95% CI, 0.452-0.920; P = .015). There was no difference in composite of cerebrovascular accident/transient ischemic attack (HR, 0.935; 95% CI, 0.725-1.207; P = .607).</p><p><strong>Conclusion: </strong>In this retrospective study of patients with AF and HFpEF, CA was associated with lower mortality and risk of acute heart failure compared with AAT.</p>","PeriodicalId":12886,"journal":{"name":"Heart rhythm","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142499178","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lateral QRS amplitude is independently associated with outcome after cardiac resynchronization therapy: Advancing patient selection?","authors":"Sander Trenson, Peter C Kahr, Judith M Schwaiger, Pascal Betschart, Joël Kuster, Bert Vandenberk, Jürgen Duchenne, Ahmed S Beela, Ivan Stankovic, Gabor Voros, Andreas J Flammer, Matthias Schindler, Ardan M Saguner, Rik Willems, Frank Ruschitzka, Jan Steffel, Alexander Breitenstein, Jens-Uwe Voigt, Stephan Winnik","doi":"10.1016/j.hrthm.2024.10.031","DOIUrl":"10.1016/j.hrthm.2024.10.031","url":null,"abstract":"<p><strong>Background: </strong>Cardiac resynchronization therapy (CRT) is a cornerstone in the treatment of selected heart failure patients. However, a relevant proportion of patients do not show beneficial response. Identification of simple, additive, and outcome-relevant selection criteria may improve selection of patients.</p><p><strong>Objective: </strong>We sought to determine whether baseline QRS amplitude is associated with outcome in CRT.</p><p><strong>Methods: </strong>Quantification of intrinsic, pre-CRT implantation QRS amplitude was performed in an observational multinational 2-center retrospective cohort analysis (derivation cohort Zurich, n = 178, 2000-2015; validation cohort Leuven, n = 183, 1999-2016) with a composite end point of all-cause mortality, ventricular assist device implantation, or heart transplantation at 5 years.</p><p><strong>Results: </strong>Higher baseline to peak amplitude in lateral leads (lead I and V₆) was associated with a lower risk of reaching the composite end point (lead I: hazard ratio, 0.86 [95% confidence interval, 0.78-0.95] per millivolt, P = .002; lead V₆: hazard ratio, 0.94 [95% confidence interval, 0.88-1.00] per millivolt, P = .043). Concordance index-based comparison of quartile, spline, and receiver operating characteristic curve analysis suggested cutoff values of 6 mV for lead I and 3 mV for V₆ for optimal discrimination of outcome. External validation confirmed the cutoff of 3 mV in lead V₆ as a highly significant discriminator of outcome (P < .001) associated with a risk reduction of 65%.</p><p><strong>Conclusion: </strong>Low QRS amplitude in lateral electrocardiogram leads is associated with higher risk of poor outcome in CRT patients. A cutoff of 3 mV in lead V₆ proved highly discriminative. Further studies need to confirm the additive value of QRS amplitude in selection of patients for CRT and to assess whether CRT may be made available to more patients.</p>","PeriodicalId":12886,"journal":{"name":"Heart rhythm","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142499181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Origin of ventricular fibrillation triggers in a model of localized repolarization heterogeneity.","authors":"Estelle Renard, Michel Haïssaguerre, Laura R Bear, Olivier Bernus","doi":"10.1016/j.hrthm.2024.10.027","DOIUrl":"10.1016/j.hrthm.2024.10.027","url":null,"abstract":"<p><strong>Background: </strong>Heterogeneities in ventricular repolarization contribute significantly to the genesis of ventricular fibrillation (VF). Although clinical arrhythmias are spontaneously triggered by premature ventricular complexes, these triggers are difficult to document and little is known about their site of origin.</p><p><strong>Objectives: </strong>The purpose of this study was to characterize spontaneous VF initiation in an experimental model of repolarization heterogeneity and to identify the origin of triggers in relation to the spatial dispersion of repolarization.</p><p><strong>Methods: </strong>Spatially limited repolarization heterogeneity was created in isolated perfused porcine right ventricles (N = 16) by local administration of pinacidil (20 μM) in a terminal branch of the right coronary artery. High-resolution optical mapping and pseudo-electrocardiography were performed in control conditions and after pinacidil perfusion.</p><p><strong>Results: </strong>No arrhythmia occurred at baseline, but 74 VF episodes were observed in 13 hearts (82%) after pinacidil perfusion and were most often initiated by a ventricular trigger with a short coupling interval (297 ± 66 ms). Sixteen VF initiations were optically mapped in 4 hearts. Mapping showed triggers originating in all cases from the border zone between altered and normal repolarization areas where local action potential duration and repolarization time gradients were steep (15.9 and 15.8 ms/mm vs 1.5 and 3.0 ms/mm in nontrigger sites). Optical action potential traces were compatible with a phase 2 reexcitation mechanism. The subsequent VF cycles were driven by activities located in the same region.</p><p><strong>Conclusion: </strong>This model of localized repolarization heterogeneity is able to produce spontaneous VF initiation. Our study demonstrates that VF triggers originate consistently from the border zone of repolarization dispersion.</p>","PeriodicalId":12886,"journal":{"name":"Heart rhythm","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142499184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chronic wireless communication between dual-chamber leadless pacemaker devices.","authors":"Rahul N Doshi, James E Ip, Pascal Defaye, Derek V Exner, Vivek Y Reddy, Gerhard Hindricks, Robert Canby, Morio Shoda, Maria G Bongiorni, Petr Neužil, Thomas Callahan, Nima Badie, David Ligon, Reinoud E Knops","doi":"10.1016/j.hrthm.2024.10.020","DOIUrl":"10.1016/j.hrthm.2024.10.020","url":null,"abstract":"<p><strong>Background: </strong>Aveir DR (Abbott, Abbott Park, IL) is a dual-chamber leadless pacemaker (LP) system with distinct atrial and ventricular LPs (ALP, VLP) that communicate wirelessly to deliver atrioventricular synchronous pacing. Success rates of these implant-to-implant (i2i) transmissions have not been systematically evaluated.</p><p><strong>Objective: </strong>This study aims to evaluate chronic i2i success rates in a clinical setting.</p><p><strong>Methods: </strong>Patients meeting standard dual-chamber pacing indications were enrolled and implanted with dual-chamber LP systems as part of a prospective international clinical trial (Aveir DR i2i Study). The percent of successful i2i transmissions from ALP-to-VLP (A-to-V) and VLP-to-ALP (V-to-A) were interrogated from LPs in de novo patients using the device programmer at implant, discharge, and at 1, 3, and 6 months postimplant (1M, 3M, 6M).</p><p><strong>Results: </strong>A total of 399 patients completed device implant and i2i diagnostic interrogation (62% male; age 69 years; 65% sinus node dysfunction, 32% atrioventricular [AV] block). Median A-to-V and V-to-A i2i success rates exceeded 90% of beats at all time-points from implant to 6M. The minority of patients with A-to-V or V-to-A i2i success in <70% of beats at implant (A-to-V: 19% of patients, V-to-A: 31% of patients) showed roughly 40% improvement by 1M, with this minority dropping to roughly 5% of patients by 6M. Improvement in i2i communication success may be attributed to reprogramming of i2i setting levels, natural changes in dominant posture, and device stabilization.</p><p><strong>Conclusion: </strong>Wireless implant-to-implant communication in the new dual-chamber leadless pacemaker system demonstrated successful transmissions in >90% of beats throughout the 6-month evaluation period. Communication success improved significantly over time postimplant for specific subgroups.</p><p><strong>Clinical trial registration: </strong>Aveir DR i2i Study, ClinicalTrials.gov ID NCT05252702.</p>","PeriodicalId":12886,"journal":{"name":"Heart rhythm","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142463362","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Varying effect of atrial fibrillation ablation in patients with heart failure with preserved ejection fraction according to CHA₂DS₂-VASc score.","authors":"Xiaodong Peng, Jiangtao Li, Nian Liu, Liu He, Xiaoxia Liu, Ning Zhou, Xin Du, Caihua Sang, Deyong Long, Jianzeng Dong, Changsheng Ma","doi":"10.1016/j.hrthm.2024.10.029","DOIUrl":"10.1016/j.hrthm.2024.10.029","url":null,"abstract":"<p><strong>Background: </strong>The impact of comorbidity burden on outcomes of radiofrequency catheter ablation (RFCA) for atrial fibrillation (AF) in patients with heart failure and preserved ejection fraction (HFpEF) remains unclear.</p><p><strong>Objective: </strong>The purpose of this study was to evaluate how comorbidity burden influences the association between RFCA and cardiovascular outcomes in AF patients with HFpEF.</p><p><strong>Methods: </strong>AF patients with HFpEF from the prospective China-AF cohort, recruited between August 2011 and December 2020, were categorized into 2 groups based CHA₂DS₂-VASc score: low comorbidity burden (score ≤4) and high comorbidity burden (score >4). The associations between RFCA and cardiovascular outcomes and interaction effects of comorbidity burden on these associations were assessed.</p><p><strong>Results: </strong>Among 1700 patients with median follow-up of 65.9 months, those in the low comorbidity burden group who received RFCA had a lower risk of composite events (cardiovascular death and ischemic stroke/transient ischemic attack [TIA]) (adjusted hazard ratio [HR] 0.35, 95% confidence interval [CI] 0.21-0.59] and all-cause death (adjusted HR 0.31, 95% CI 0.17-0.54) compared to those without RFCA. However, significant associations were not observed in the high comorbidity burden group. The differences between low and high comorbidity burden groups were significant, with interaction effects noted between comorbidity burden and RFCA for cardiovascular death (P_interaction = 0.045) and ischemic stroke/TIA (P_interaction = 0.010). RFCA was associated with a reduced risk of AF recurrence in both comorbidity burden groups.</p><p><strong>Conclusion: </strong>RFCA for AF is associated with reduced AF recurrence and improved cardiovascular outcomes in patients with HFpEF. However, these benefits may be limited for patients with a CHA₂DS₂-VASc score >4 (high comorbidity burden).</p>","PeriodicalId":12886,"journal":{"name":"Heart rhythm","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142463386","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Feasibility and safety assessment of RF double applications in very high power and short duration ablation.","authors":"Junji Yamaguchi, Masateru Takigawa, Masahiko Goya, Hidehiro Iwakawa, Iwanari Kawamura, Miho Negishi, Tasuku Yamamoto, Takashi Ikenouchi, Kentaro Goto, Takatoshi Shigeta, Takuro Nishimura, Tomomasa Takamiya, Susumu Tao, Sayaka Suzuki, Takehiro Iwanaga, Shinsuke Miyazaki, Tetsuo Sasano","doi":"10.1016/j.hrthm.2024.10.026","DOIUrl":"10.1016/j.hrthm.2024.10.026","url":null,"abstract":"<p><strong>Background: </strong>Very high power and short duration (vHPSD) ablation is recently used for pulmonary vein isolation. However, low first-pass isolation rates have been reported, possibly because of shallow lesion formation, necessitating deeper lesions to improve treatment outcomes.</p><p><strong>Objective: </strong>This study aimed to confirm the safety and efficacy of double radiofrequency applications of vHPSD ablation in an in vivo beating swine heart model.</p><p><strong>Methods: </strong>Eighteen swine were anesthetized and underwent vHPSD ablation using the QDOT-MICRO catheter at 90 W for 4 seconds, targeting a contact force of 10 g. Radiofrequency applications were performed as single application (SA) and double applications (DA) with 4-8 seconds rest intervals. Lesion surface area and volume were measured postablation.</p><p><strong>Results: </strong>A total of 337 atrial lesions and 74 ventricular lesions were created. Both 4-6 seconds DA and 7-8 seconds DA produced significantly larger and deeper lesions than did SA, with atrial surface lengths averaging 9.0 mm for 4-6 seconds DA, 9.2 mm for 7-8 seconds DA, and 8.0 mm for SA. Transmurality was observed at 100% for 4-6 seconds and 7-8 seconds DAs, while it was 94% for SA (P = .002). Ventricular lesion metrics followed similar trends. Except for 1 event of tiny char formation during 4 seconds DA in the ventricle, neither steam pops nor char formation was observed in either the atrium or the ventricle.</p><p><strong>Conclusion: </strong>In an in vivo swine heart model, DA with 4-6 seconds and 7-8 seconds intervals create deeper and wider lesions than does SA, suggesting its potential for clinical application in areas with thicker myocardial walls. However, DA with very short intervals may still pose a risk of excessive tissue heating.</p>","PeriodicalId":12886,"journal":{"name":"Heart rhythm","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142463377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Circulating ketone bodies, genetic susceptibility, with left atrial structure, function and atrial fibrillation: A prospective study from the UK Biobank.","authors":"Nan Zhang, Daiqi Liu, Jinhua Zhao, Gary Tse, Jiandong Zhou, Qingpeng Zhang, Gregory Y H Lip, Tong Liu","doi":"10.1016/j.hrthm.2024.10.028","DOIUrl":"10.1016/j.hrthm.2024.10.028","url":null,"abstract":"<p><strong>Background: </strong>Ketone bodies (KBs) are an important cardiac metabolic energy source. Metabolic remodeling has recently been found to play an important role in the pathological process of atrial fibrillation (AF).</p><p><strong>Objective: </strong>The purpose of this study was to evaluate the associations of circulating KB levels with incident AF risk in the general population.</p><p><strong>Methods: </strong>We studied 237,163 participants (mean age 56.5 ± 8.1 years; 55% women) from the UK Biobank who were free of AF at baseline and had data on circulating β-hydroxybutyrate (β-OHB), acetoacetate, and acetone. The associations of KB with new-onset AF were evaluated using Cox regression in the general population and across the 3 genetic risk groups: low, moderate, and high polygenic risk score of AF.</p><p><strong>Results: </strong>During a median follow-up of 14.8 years, 16,638 participants (7.0%) developed AF. There was a U-shaped association of total KB and β-OHB with incident AF, with nadirs at 60.6 and 40.8 μmol/L, respectively (P_nonlinear < .05), whereas there was a positive association of acetoacetate and acetone with AF (P_overall < .001; P_nonlinear > .05). Consistently, there was a U-shaped association of total KB and β-OHB with left atrial (LA) volume parameters, including LA maximum volume, LA minimum volume, and their body surface area-indexed counterparts, and there was an inverted U-shaped association of total KB with LA ejection fraction (P_nonlinear < .05 for all). The association of KB with AF was stronger in individuals with low genetic risk (P_interaction < .05), while the highest AF risk was in those with high genetic risk with high KB levels. Significant mediation effects of inflammatory markers on the associations between KB and AF were identified.</p><p><strong>Conclusion: </strong>There was a U-shaped association of circulating total KB and β-OHB with incident AF as well as a positive association of acetoacetate and acetone levels with AF risk in the general population.</p>","PeriodicalId":12886,"journal":{"name":"Heart rhythm","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142463364","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Remnant cholesterol and new-onset atrial fibrillation: The Atherosclerosis Risk in Communities study.","authors":"Xiaolan Ouyang, Xixiang Tang, Long Peng, Hongxing Wu, Jiafu Wang, Zhuoshan Huang, Bingyuan Wu, Yue Li, Yan Lu, Xiaodong Zhuang, Yesheng Ling, Suhua Li","doi":"10.1016/j.hrthm.2024.10.030","DOIUrl":"10.1016/j.hrthm.2024.10.030","url":null,"abstract":"<p><strong>Background: </strong>The relationship between remnant cholesterol (RC) and atrial fibrillation (AF) remains unclear.</p><p><strong>Objective: </strong>The purpose of this study was to comprehensively explore the association between RC characteristics and new-onset AF.</p><p><strong>Methods: </strong>Data from 5 follow-up visits of the ARIC (Atherosclerosis Risk in Communities) study were analyzed. RC were multidimensionally evaluated in 4 characteristics: baseline level, variability, cumulative exposure, and trajectory. Baseline RC was obtained from the initial visit (V1), and new-onset AF was monitored in V2 to V5 (cohort 1, n = 14,450). RC variability, cumulative RC, and RC trajectory were calculated by RC values gathered from V1 to V3, and new-onset AF was monitored in V4 and V5 (cohort 2, n = 11,012). Participants were divided into 4 groups based on quartiles or trajectories. Cox proportional hazards analyses were used to investigate the relationship between RC characteristics and AF.</p><p><strong>Results: </strong>Following median follow-up of 22.39 years in cohort 1 and 16.71 years in cohort 2, a total of 1993 AF events in cohort 1 and 1571 in cohort 2 were identified. Participants with the highest quartile exhibited an elevated risk of new-onset AF, with the multivariable-adjusted hazard ratios of 1.16 (P = .039) for baseline RC and 1.30 (P < .001) for RC variability. Although the highest quartile of cumulative RC (P = .241) and the high-increasing trajectory (P = .210) did not demonstrate a statistically significant association with AF occurrence, they indicate a trend toward heightened risk.</p><p><strong>Conclusion: </strong>Our findings reveal that higher levels of RC, particularly at baseline and in variability, are associated with an increased risk of AF.</p>","PeriodicalId":12886,"journal":{"name":"Heart rhythm","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142463381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Calmodulin kinase II inhibition suppresses atrioventricular conduction by regulating intracellular Ca²⁺ homeostasis.","authors":"Yuan Chen, Hongfei Wang, Baijun Xuan, Chaorui Xia, Ting Li, Yidi Meng, Peiwu Ding, Yun Huang, Guanhua Su, Jiaming Zhang, Jingdong Li","doi":"10.1016/j.hrthm.2024.10.022","DOIUrl":"10.1016/j.hrthm.2024.10.022","url":null,"abstract":"<p><strong>Background: </strong>Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) inhibition decelerates atrioventricular node (AVN) conduction, providing a potential treatment of tachycardia. However, the effectiveness of CaMKII inhibition on tachycardia and its underlying mechanism remains unclear.</p><p><strong>Objective: </strong>We aimed to assess the effectiveness of CaMKII inhibition in reducing ventricular rates during atrial fibrillation and to elucidate the underlying mechanism in affecting AVN electrophysiology.</p><p><strong>Methods: </strong>Cardiac CaMKII inhibition (AC3-I) mice were used. Transesophageal atrial pacing was performed to evaluate AVN conduction function and to induce atrial fibrillation. Patch-clamp techniques were employed to record action potentials and ionic currents in AVN cells. Intracellular Ca²⁺ transients and sarcomere length measurements were obtained with the IonOptix system. Masson trichrome stain was used to evaluate fibrosis in the AVN region. Western blotting and immunofluorescence techniques were employed to detect connexin expression and localization.</p><p><strong>Results: </strong>CaMKII inhibition decreased the ventricular rate during atrial fibrillation and isoproterenol-induced tachycardia. Esophageal electrocardiogram results from AC3-I mice showed longer AVN conduction than in wild-type mice. AN- and N-type AVN cells from AC3-I mice exhibited slower action potential frequencies and diastolic depolarization rates than those of wild-type mice. The study revealed that CaMKII inhibition reduced AVN cell sarcoplasmic reticulum (SR) Ca²⁺ content, Ca²⁺ release rate from the SR during diastole, Ca²⁺ transient amplitude, and SR Ca²⁺ uptake rate. In addition, CaMKII inhibition prolonged the sarcomere diastole duration and enhanced the sensitivity of sarcomeres to Ca²⁺.</p><p><strong>Conclusion: </strong>CaMKII inhibition effectively decreases the ventricular rate during atrial fibrillation and tachycardia by slowing down AVN conduction through suppressing Ca²⁺ overload in AVN cells.</p>","PeriodicalId":12886,"journal":{"name":"Heart rhythm","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142463360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Use of artificial intelligence algorithms to reduce transmissions in implantable loop recorders.","authors":"Melissa E Middeldorp, Gijo Thomas, Suraya H Kamsani, Curtis Harper, Tina Baykaner, Rakesh Gopinathannair, James V Freeman, Andrea M Russo, Thomas F Deering, Prashanthan Sanders","doi":"10.1016/j.hrthm.2024.10.024","DOIUrl":"10.1016/j.hrthm.2024.10.024","url":null,"abstract":"","PeriodicalId":12886,"journal":{"name":"Heart rhythm","volume":null,"pages":null},"PeriodicalIF":5.6,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142463385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}