X-Linked Sinus Node Dysfunction and Atrial Fibrillation. Introduction: Atrial fibrillation (AF) is a heritable disorder with male predilection, suggesting a sex chromosome defect in certain patients. Loss-of-function truncation mutations in EMD, encoding the nuclear membrane protein emerin, cause X-linked Emery-Dreifuss muscular dystrophy (EDMD) characterized by localized contractures and skeletal myopathy in adolescence, sinus node dysfunction (SND) in early adulthood, and atrial fibrillation as a variably associated trait. This study sought to identify the genetic basis for male-restricted, nonsyndromic sinus node dysfunction and AF in a multigenerational family. Methods and Results: Genealogical and medical records, and DNA samples, were obtained. Progressive SND and AF occurred in four males related through maternal lineages, consistent with X-linked inheritance. Skeletal myopathy was absent, even at advanced ages. Targeted X chromosome genotyping mapped the disease locus to Xq28, implicating EMD as a positional candidate gene. DNA sequencing revealed hemizygosity for an in-frame 3-bp deletion in EMD (Lys37del) in affected males, disrupting a residue within the LEM binding domain critical for nuclear assembly but leaving the remainder of the protein intact. Buccal epithelial cell staining with emerin antibody demonstrated near-total functional loss of emerin. Female relatives underwent prospective electrocardiographic and genetic testing. Those heterozygous for Lys37del had ∼50-70% emerin-positive nuclei and variable degrees of paroxysmal supraventricular arrhythmia. Conclusions: Mutation of EMD can underlie X-linked familial AF. Lys37del is associated with epithelial cell emerin deficiency, as in EDMD, yet it causes electrical atriomyopathy in the absence of skeletal muscle disease. Targeted genetic testing of EMD should be considered in patients with SND-associated AF and/or family history suggesting X-linked inheritance.

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Atrial fibrillation (AF) is associated with high risk of systemic thromboembolism leading to significant morbidity and mortality. Warfarin, previously the mainstay for stroke prevention in AF, requires close monitoring because of multiple food and drug interactions. In recent years, food and drug administration has approved several direct oral anticoagulants (DOACs) for use in patients with nonvalvular AF. These agents have not been studied in patients with valvular AF who are at an even higher risk of systemic thromboembolism. DOACs do not require frequent blood testing or changes in dosage except when renal function deteriorates, however, the lack of established antidotes for many of these agents remains a challenge. Also, currently there is no head-to-head comparison between these agents to guide clinical choice. This article discusses the advantages and disadvantages of currently approved oral antithrombotics in nonvalvular AF, with a special emphasis on the DOACs and their individual characteristics.

Patients with atrial fibrillation (AF) are at increased risk of stroke. Warfarin anticoagulation therapy reduces the incidence of stroke and increases the incidence of hemorrhagic events. This dissertation further informs the decision to use anticoagulation therapy in AF patients by examining outcomes in patients with major hemorrhages, further examination of stroke risk in diabetic patients with AF, and by evaluating the association between warfarin and stroke while accounting for competing risk events. These studies utilized data from the AnTicoagulation and Risk Factors In Atrial Fibrillation (ATRIA) and ATRIA-CVRN (Cardiovascular Research Network) (Study 1 only) studies which consist of patients from Kaiser Permanente Northern and Southern California. Study 1 examined short and long-term mortality in patients who experienced major gastrointestinal (GI) hemorrhages. In the ATRIA cohort, patients using and not using warfarin at the time of GI hemorrhage were equally likely to die within 30-days, while in ATRIA-CVRN, patients using warfarin were much less likely to die within 30-days (adjusted mortality rate ratio (aMRR): 0.33, 95% CI: 0.16-0.70). For longer-term mortality, both cohorts were consistent with a reduced mortality rate among patients whose GI hemorrhage occurred while using warfarin. Study 2 assessed the association between diabetes characteristics (duration of diabetes and glycemic control) and incidence of ischemic stroke among patients with AF and diabetes. Duration ≥ 3 years was associated with a large increase in rate of stroke (adjusted hazard ratio (aHR): 2.04, 95% CI: 1.27-3.26) compared to patients with duration < 3 years. Patients with the poorest glycemic control (hemoglobin A1c (HbA1c) values ≥ 9.0%) did not have an increased rate of ischemic stroke compared to patients with HbA1c < 7.0%. Study 3 evaluated the association between warfarin and thromboembolism in analyses that did and did not account for competing death events. In analyses not accounting for competing events, the adjusted HR was 0.61 (95% CI: 0.54-0.69), and after accounting for competing death events this association was attenuated (aHR: 0.87, 95% CI: 0.77-0.99). In summary, these studies add to the literature about the benefits of warfarin therapy and risk of stroke in patients with AF, findings that can improve decisions about use of anticoagulants in patients with AF.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第18868号 / 医博第3979号 / 新制||医||1008(附属図書館) / 31819 / 京都大学大学院医学研究科医学専攻 / (主査)教授 横出 正之, 教授 坂田 隆造, 教授 川村 孝 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(社会健康医学) / 甲第20626号 / 社医博第84号 / 社新制||医||9(附属図書館) / 京都大学大学院医学研究科社会健康医学系専攻 / (主査)教授 佐藤 俊哉, 教授 木村 剛, 教授 川村 孝 / 学位規則第4条第1項該当 / Doctor of Public Health / Kyoto University / DFAM

ABSTRACT Atrial fibrillation (AF) is frequently detected in the setting of an acute physiologic stressor, such as medical illness or surgery. It is uncertain if AF detected in these settings (AFOTS: AF occurring transiently with stress) is secondary to a reversible trigger or is simply paroxysmal AF. This distinction is critical for clinicians and patients, as they must decide if AFOTS can be dismissed as a reversible phenomenon, or if it justifies the need for chronic therapy; in particular, anticoagulation to reduce the risk of disabling stroke. The uncertainty in the management of AFOTS is exacerbated by a poor understanding of its epidemiology. How frequently does AFOTS occur? Are there higher risk groups? What is the natural history of this condition? Across 8 chapters, this thesis systematically assesses previously published literature on this topic, focusing on patients who have an acute medical illness or have undergone noncardiac surgery, and addresses knowledge gaps therein. Chapter 1 is an introduction that outlines the justification of each of the studies in the thesis. Chapter 2 is a narrative review that defines AFOTS conceptually and outlines research priorities. Chapter 3 is a systematic review that explores the incidence and recurrence of AFOTS associated with acute medical illness. Chapter 4 is a systematic review and meta-analysis that explores the incidence and recurrence of AFOTS associated with acute noncardiac surgery. iii Chapter 5 examines the profiles of pacemaker-detected “subclinical” AF occurring before and after a hospitalization for medical illness or noncardiac surgery Chapter 6 reports the design, rationale and final results of a prospective study that aimed to provide a precise and accurate estimate of the incidence of AFOTS in critically ill patients. Chapter 7 reports the design and rationale of a matched prospective cohort study designed to estimate the rate of recurrence of AF following hospitalization with AFOTS and to compare it to similar patients who did not have AFOTS. Finally, Chapter 8 outlines the conclusions, discusses the limitations, and presents the implications of the research in this PhD thesis. / Thesis / Doctor of Philosophy (PhD) / Atrial fibrillation (AF) is the most common abnormal heart rhythm. AF is often diagnosed when a patient is hospitalized for an illness or after surgery. When AF is first found in this setting, it is unclear whether it has the same prognosis as other forms of the disease or is reversible. This thesis examines this problem and designs and executes studies to address it.

Almost half of patients recovering from open chest surgery experience atrial fibrillation (AF) that results principally from inflammation in the pericardial space surrounding the heart. Given that post-operative AF is associated with increased mortality, effective measures to prevent AF after open-chest surgery are highly desirable. In this study, we tested the concept that extracellular vesicles (EVs) isolated from human atrial explant-derived cells can prevent post-operative AF. Middle-aged female and male rats were randomized to undergo sham operation or induction of sterile pericarditis followed by trans-epicardial injection of human EVs or vehicle into the atrial tissue. Pericarditis increased the probability of inducing AF while EV treatment abrogated this effect in a sex independent manner. EV treatment reduced infiltration of inflammatory cells and production of pro-inflammatory cytokines. Atrial fibrosis and hypertrophy seen after pericarditis was markedly attenuated by EV pre-treatment; an effect attributable to suppression of fibroblast proliferation by EVs. Our study demonstrates that injection of extracellular vesicles at the time of open-chest surgery shows prominent anti-inflammatory effects and prevents AF due to sterile pericarditis. Translation of this finding to patients might provide an effective new strategy to prevent post-operative AF by reducing atrial inflammation and fibrosis.

To review the literature on treatment of venous thromboembolism (VTE) and prevention of cardioembolic stroke with direct-acting oral anticoagulants (DOACs) in low- and high-body-weight patients and to make recommendations regarding agent selection and dosing in these patient populations. Summary: The selection and optimal dosing of DOACs in low- and high-body-weight patients has not yet been fully elucidated by clinical trials; however, evidence suggests that issues of both safety and efficacy in patients at the extremes of body weight may warrant careful consideration when selecting a DOAC for such patients. This review provides a thorough discussion of the use of DOACs in the treatment of VTE and prevention of cardioembolic stroke in patients at the extremes of body weight and provides guidance regarding agent selection. Conclusion: While the published evidence on use of DOACs in patients at extremes of body weight is sparse, apixaban and rivaroxaban appear to have the most favorable safety and efficacy profiles. Edoxaban and dabigatran should be avoided.

Atrial fibrillation (AFIB) is the most common heart rhythm abnormality and is associated with significant morbidity and mortality. While the treatment of AFIB involves strategies of rate with or without rhythm control, it is also essential to strategize appropriate therapies to prevent thromboembolic complications arising from AFIB. Previously, anticoagulation was the main treatment option which exposed patients to higher than usual risk of bleeding. However, with the advent of new technology, novel therapeutic options aimed at surgical or percutaneous exclusion or occlusion of the left atrial appendage in preventing thromboembolic complications from AFIB have evolved. This review evaluates recent advances and therapeutic options in treating AFIB with a special focus on both surgical and percutaneous interventions which can reduce and/or eliminate thromboembolic complications of AFIB.