BACKGROUND: Clonal hematopoiesis of indeterminate potential (CHIP), a common age-associated phenomenon, associates with increased risk of both hematological malignancy and cardiovascular disease. Although CHIP is known to increase the risk of myocardial infarction and heart failure, the influence of CHIP in cardiac arrhythmias, such as atrial fibrillation (AF), is less explored. METHODS: CHIP prevalence was determined in the UK Biobank, and incident AF analysis was stratified by CHIP status and clone size using Cox proportional hazard models. Lethally irradiated mice were transplanted with hematopoietic-specific loss of Tet2, hematopoietic-specific loss of Tet2 and Nlrp3, or wild-type control and fed a Western diet, compounded with or without NLRP3 (NLR [NACHT, LRR {leucine rich repeat}] family pyrin domain containing protein 3) inhibitor, NP3-361, for 6 to 9 weeks. Mice underwent in vivo invasive electrophysiology studies and ex vivo optical mapping. Cardiomyocytes from Ldlr-/- mice with hematopoietic-specific loss of Tet2 or wild-type control and fed a Western diet were isolated to evaluate calcium signaling dynamics and analysis. Cocultures of pluripotent stem cell-derived atrial cardiomyocytes were incubated with Tet2-deficient bone marrow-derived macrophages, wild-type control, or cytokines IL-1ß (interleukin 1ß) or IL-6 (interleukin 6). RESULTS: Analysis of the UK Biobank showed individuals with CHIP, in particular TET2 CHIP, have increased incident AF. Hematopoietic-specific inactivation of Tet2 increases AF propensity in atherogenic and nonatherogenic mouse models and is associated with increased Nlrp3 expression and CaMKII (Ca2+/calmodulin-dependent protein kinase II) activation, with AF susceptibility prevented by inactivation of Nlrp3. Cardiomyocytes isolated from Ldlr-/- mice with hematopoietic inactivation of Tet2 and fed a Western diet have impaired calcium release from the sarcoplasmic reticulum into the cytosol, contributing to atrial arrhythmogenesis. Abnormal sarcoplasmic reticulum calcium release was recapitulated in cocultures of cardiomyocytes with the addition of Tet2-deficient macrophages or cytokines IL-1ß or IL-6. CONCLUSIONS: We identified a modest association between CHIP, particularly TET2 CHIP, and incident AF in the UK Biobank population. In a mouse model of AF resulting from hematopoietic-specific inactivation of Tet2, we propose altered calcium handling as an arrhythmogenic mechanism, dependent on Nlrp3 inflammasome activation. Our data are in keeping with previous studies of CHIP in cardiovascular disease, and further studies into the therapeutic potential of NLRP3 inhibition for individuals with TET2 CHIP may be warranted.
Atrial Fibrillation , Clonal Hematopoiesis , DNA-Binding Proteins , Dioxygenases , Inflammasomes , NLR Family, Pyrin Domain-Containing 3 Protein , Proto-Oncogene Proteins , Animals , Dioxygenases/metabolism , Dioxygenases/genetics , NLR Family, Pyrin Domain-Containing 3 Protein/metabolism , NLR Family, Pyrin Domain-Containing 3 Protein/genetics , Atrial Fibrillation/metabolism , Atrial Fibrillation/etiology , Atrial Fibrillation/genetics , Atrial Fibrillation/pathology , Inflammasomes/metabolism , Humans , Mice , Clonal Hematopoiesis/genetics , Proto-Oncogene Proteins/metabolism , Proto-Oncogene Proteins/genetics , Male , DNA-Binding Proteins/genetics , DNA-Binding Proteins/metabolism , Female , Aged , Myocytes, Cardiac/metabolism , Myocytes, Cardiac/pathology , Middle Aged , Mice, Knockout , Risk Factors
Background: Lifestyle modification programs, such as cardiac rehabilitation, may reduce atrial fibrillation (AF) burden and improve quality of life (QOL), but remain unproven. The objective of this pilot study was to assess feasibility, acceptability, and preliminary effectiveness of an exercise and nutrition-based cardiac rehabilitation-like program for AF patients. Methods: We enrolled overweight adults aged ≥ 30 years with symptomatic AF in a 12-week cardiac lifestyle group program, including 6 virtual and 6 in-person visits. All visits included discussion and education about nutrition, exercise, and behavior modification. In-person visits included supervised aerobic exercise and strength training. Outcomes at baseline and 12 weeks included feasibility of participation, acceptability, change in weight and BMI, and changes in survey-based AF burden, symptoms, and QOL. Results: From 84 invitees, 11 (13.1%) were enrolled (mean age 64; baseline BMI 38 kg/m2); 9 (82%) completed the program. Patients attended an average of 9.7 (81%) visits (Range: 6-11). Mean weight loss was 9.1 pounds (Range: 0-16); mean BMI decrease was 1.4 kg/m2 (Range: 0-2.6). Patients found the program helpful overall: all reported making diet and exercise changes during the program. Compared to baseline, patients reported decreased AF burden (12.9 vs. 11.7, p = 0.03) and symptom (10.1 vs. 5.6, p = 0.003) scores at the conclusion of the program. Patients also reported increased QOL overall (68.9 vs. 86.4, p = 0.001). Conclusions: Participation in a cardiac rehab-like program was feasible and acceptable for overweight patients with symptomatic AF. Results suggest preliminary effectiveness of the program for reducing AF burden and symptoms and increasing QOL.
