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Abstract Aims Right ventricular (RV) allograft dysfunction is present in half of all heart transplant (HT) recipients. Non‐invasive assessment of RV function in the setting of rejection is not well described. We outline an echocardiographic technique, short‐axis fractional area change (SAXFAC), to evaluate RV function in the HT population and correlate this with the grade of pathologic rejection. Methods and results We retrospectively reviewed the electronic medical records of 110 people who received a HT between 1 January 2015 and 29 February 2020 and had no evidence of rejection. One hundred eighty‐two transthoracic echocardiograms (TTEs) completed up to 1 year from the date of transplantation were analysed for the target acoustic window, the parasternal mid‐ventricular short‐axis view. Sixty‐one TTEs from 23 healthy transplants were deemed appropriate for SAXFAC determination. Thirty‐three organ recipients with at least grade 1R allograft rejection were also identified, and their TTEs screened for SAXFAC analysis. Two expert readers independently calculated SAXFAC as follows: RV end‐diastolic area minus end‐systolic area divided by end‐diastolic area. Using commercially available software (Epsilon, Ann Arbor, Michigan), we quantified RV radial strain, longitudinal strain, and apical fractional area change (FAC). Twenty‐eight transplant recipients with grade 0R or 1R rejection and nine patients with clinically significant rejection completed the study analysis. SAXFAC demonstrated significant variability in the entire population with an inverse relationship to severity of allograft rejection (P ≤ 0.01). Radial strain and FAC were also associated with clinically significant rejection (P ≤ 0.01). Conclusions Short‐axis fractional area change is a simple two‐dimensional technique to assess RV function in HT recipients and showed no significant inter‐observer variability. In our small, single‐centre, retrospective case series, lower SAXFAC values were associated with clinically significant allograft rejection. The small sample size and infrequent occurrence of rejection make our observations hypothesis‐generating only. We advocate dedicated RV SAXFAC imaging planes be included when assessing allograft function.

BackgroundCardiac tumors are usually metastatic. Melanoma is the tumor with the highest rate of cardiac metastasis. Clinicians need to be aware of the metastatic involvement of the left ventricular apex as a differential diagnosis of apical hypertrophic cardiomyopathy.Case summaryA 74-year-old woman presented for evaluation of fatigue. The initial electrocardiogram and echocardiogram showed features of apical hypertrophic cardiomyopathy. The patient reported a lesion on her right forearm that had been present for many years, leading to its biopsy, which showed melanoma. Further evaluation with a chest-computed tomography (CT) scan showed left lung nodules and nodular thickening of the left ventricular apex. Positron emission tomography showed an increased uptake of fluorodeoxyglucose in the left lung nodule and left ventricular apex, suggestive of metastatic spread of the melanoma. A CT-guided biopsy of the left lung nodule revealed melanoma. The patient was treated with ipilimumab initially, followed by paclitaxel with poor response to treatment, and later passed under hospice care.ConclusionMetastatic tumors involving the left ventricular apex should be considered in the differential diagnosis of apical hypertrophic cardiomyopathy, especially in patients with a history of melanoma, and advanced cardiac imaging, including cardiac magnetic resonance imaging, CT, and/or positron emission tomography (PET) may help with narrowing down the differential diagnosis.

Chronic exposure to silica is a recognized health hazard. Manifestations of pulmonary and extrapulmonary silicosis are well described. Secondary pulmonary arterial hypertension and pericardial involvement are described, but myocardial involvement has not been reported. In this case of newly diagnosed pulmonary silicosis, ventricular tachycardia results are shown from pathological involvement of ventricular myocardium. (Level of Difficulty: Beginner.)

Background Age‐related heart diseases are significant contributors to increased morbidity and mortality. Emerging evidence indicates that mitochondria within cardiomyocytes contribute to age‐related increased reactive oxygen species (ROS) generation that plays an essential role in aging‐associated cardiac diseases. Methods and Results The present study investigated differences between ROS production in cardiomyocytes isolated from adult (6 months) and aged (24 months) Fischer 344 rats, and in cardiac tissue of adult (18–65 years) and elderly (>65 years) patients with preserved cardiac function. Superoxide dismutase inhibitable ferricytochrome c reduction assay (1.32±0.63 versus 0.76±0.31 nMol/mg per minute; P=0.001) superoxide and H2O2 production, measured as dichlorofluorescein diacetate fluorescence (1646±428 versus 699±329, P=0.04), were significantly higher in the aged versus adult cardiomyocytes. Similarity in age‐related alteration between rats and humans was identified in mitochondrial‐electron transport chain‐complex‐I‐associated increased oxidative‐stress by MitoSOX fluorescence (53.66±18.58 versus 22.81±12.60; P=0.03) and in 4‐HNE adduct levels (187.54±54.8 versus 47.83±16.7 ng/mg protein, P=0.0063), indicative of increased peroxidation in the elderly. These differences correlated with changes in functional enrichment of genes regulating ROS homeostasis pathways in aged human and rat hearts. Functional merged collective network and pathway enrichment analysis revealed common genes prioritized in human and rat aging‐associated networks that underlay enriched functional terms of mitochondrial complex I and common pathways in the aging human and rat heart. Conclusions Aging sensitizes mitochondrial and extramitochondrial mechanisms of ROS buildup within the heart. Network analysis of the transcriptome highlights the critical elements involved with aging‐related ROS homeostasis pathways common in rat and human hearts as targets.

Vagal nerve stimulators are devices used to treat medically refractory epilepsy. Here, we present a rare, unique, and life-threatening side effect of vagal nerve stimulator placement. (Level of Difficulty: Advanced.)

Abstract Aims Fibroblast to myofibroblast trans‐differentiation with altered bioenergetics precedes cardiac fibrosis (CF). Either prevention of differentiation or promotion of de‐differentiation could mitigate CF‐related pathologies. We determined whether 3‐hydroxy‐3‐methyl‐glutaryl‐coenzyme A (HMG‐CoA) reductase inhibitors—statins, commonly prescribed to patients at risk of heart failure (HF)—can de‐differentiate myofibroblasts, alter cellular bioenergetics, and impact the human ventricular fibroblasts (hVFs) in HF patients. Methods and results Either in vitro statin treatment of differentiated myofibroblasts (n = 3–6) or hVFs, isolated from human HF patients under statin therapy (HF + statin) vs. without statins (HF) were randomly used (n = 4–12). In vitro, hVFs were differentiated by transforming growth factor‐β1 (TGF‐β1) for 72 h (TGF‐72 h). Differentiation status and cellular oxygen consumption rate (OCR) were determined by α‐smooth muscle actin (α‐SMA) expression and Seahorse assay, respectively. Data are mean ± SEM except Seahorse (mean ± SD); P

Bidirectional ventricular tachycardia (BDVT), a rare ventricular arrhythmia, is commonly caused by digitalis toxicity or channelopathies and is rarely caused by aconite toxicity, myocarditis, infarction, or sarcoidosis. This paper describes a patient with BDVT, recurrent syncope, myocardial disarray, and interstitial fibrosis on histology but normal results on echocardiography with variants in the TTN, KCNH2, and GATA4 genes. (Level of Difficulty: Advanced.)

BackgroundThe risk of thromboembolism and bleeding before initiation of oral anticoagulant (OAC) in atrial fibrillation patients is estimated by CHA2DS2-VASc and HAS-BLED scoring system, respectively. Patients' socioeconomic status (SES) could influence these risks, but its impact on the two risk scores' predictive performance with respect to clinical events remains unknown. Our objective was to determine if patient SES defined by area deprivation index (ADI), in conjunction with CHA2DS2-VASc and HAS-BLED scores, could guide oral anticoagulation therapy.Methods and findingsThe study cohort included newly diagnosed patients with AF who were treated with warfarin. The cohort was stratified by the time in therapeutic range of INR (TTR), ADI, CHA2DS2-VASc, and HAS-BLED risk scores. TTR and ischemic and bleeding events during the first year of therapy were compared across subpopulations. Among 7274 patients, those living in the two most deprived quintiles (ADI ≥60%) had a significantly higher risk of ischemic events and those in the most deprived quintile (ADI≥80%) had a significantly increased risk of bleeding events. ADI significantly improved the predictive performance of CHA2DS2-VASc but not HAS-BLED risk scores.ConclusionADI can predict increased risk for ischemic and bleeding events in the first year of warfarin therapy in patients with incident AF.

Delayed perforation of the coronary artery and extraluminal migration of coronary stent is a rare phenomenon. We report a case in which the stent was documented to perforate the coronary artery at least 1 year after the intervention and migrated within the pericardium without any symptom. (Level of Difficulty: Intermediate.)

Excessive cardiac fibrosis, characterized by increased collagen-rich extracellular matrix (ECM) deposition, is a major predisposing factor for mechanical and electrical dysfunction in heart failure (HF). The human ventricular fibroblast (hVF) remodeling mechanisms that cause excessive collagen deposition in HF are unclear, although reports suggest a role for intracellular free Ca2+ in fibrosis. Therefore, we determined the association of differences in cellular Ca2+ dynamics and collagen secretion/deposition between hVFs from failing and normal (control) hearts. Histology of left ventricle sections (Masson trichrome) confirmed excessive fibrosis in HF versus normal. In vitro, hVFs from HF showed increased secretion/deposition of soluble collagen in 48 h of culture compared with control [85.9±7.4 µg/106 cells vs 58.5±8.8 µg/106 cells, P

PurposeHigh calorie intake leads to obesity, a global socio-economic and health problem, reaching epidemic proportion in children and adolescents. Saturated and monounsaturated fatty acids from animal (lard) fat are major components of the western-pattern diet and its regular consumption leads to obesity, a risk factor for cardiovascular disease. However, no clear evidence exists whether consumption of diet rich in saturated (SFAs) and monounsaturated (MUFAs) fatty acids has detrimental effects on cardiac structure and energetics primarily due to excessive calories. We, therefore, sought to determine the impact of high calories versus fat content in diet on cardiac structure and mitochondrial energetics.MethodsSix-week-old C57BL/6J mice were fed with high calorie, high lard fat-based diet (60% fat, HFD), high-calorie and low lard fat-based diet (10% fat, LFD), and lower-calorie and fat diet (standard chow, 12% fat, SCD) for 10 weeks.ResultsThe HFD- and LFD-fed mice had higher body weight, ventricular mass and thickness of posterior and septal wall with increased cardiomyocytes diameter compared to the SCD-fed mice. These changes were associated with a reduction in the mitochondrial oxidative phosphorylation (OXPHOS) complexes I and III activity compared to the SCD-fed mice without significant differences between the HFD- and LFD-fed animals. The HFD-fed animals had higher level of malondialdehyde (MDA) than LFD and SCD-fed mice.ConclusionsWe assume that changes in cardiac morphology and selective reduction of the OXPHOS complexes activity observed in the HFD- and LFD-fed mice might be related to excessive calories with additional effect of fat content on oxidative stress.

In an aged population, cardiovascular disease is the leading cause of fatality and morbidity. Age-related fibrotic remodeling of the heart contributes to progressive myocardial dysfunction. Cardiac fibroblasts (CF), responsible for the maintenance of extracellular matrix and fibrosis process, play an important role in cardiac health and disease. CFs influence myocardial function by their chemical, electrical and mechanical interactions with cardiomyocytes through extracellular matrix deposition or secretion of cytokines and growth factors. These, in turn, are modulated by ion channels, macromolecular pores in the plasma membrane that allow selective ionic fluxes of major ions like K+, Ca2+, Na+ or Cl-, which affect membrane potential and cellular signal transduction. The importance of ion channels in modulating various functions of CFs, including proliferation, differentiation, secretion and apoptosis, is being recognized from recent studies of CFs from animal models and tissue from patients with various cardiac pathologies. Understanding the role of ion channels in CFs under physiological conditions and their alterations in age-related cardiac diseases may help facilitate development of novel therapeutic strategies to limit cardiac fibrosis and its adverse effect on myocardial function. This narrative review summarizes the knowledge gained thus far on ion channels in CFs and their relationship with cardiac diseases in human and experimental animal models.

Purpose: Excessive fibrosis has been suggested to result from persistence of fibroblasts in injured tissue due to impaired apoptosis, but signaling pathways are not fully defined. Methods: Suppression of apoptotic cell death following transforming growth factor-β1 (TGF-β1) exposure was studied using the culture of NIH/3T3 mouse embryonic fibroblasts. Caspase-3 activity, propidium iodide staining and annexin V binding induced by Fas-ligand (FasL) in NIH/3T3 fibroblasts in the absence and presence of TGF-β1 was determined, and relative contribution of signaling through Smad2/3 and noncanonical Erk1/2 and Akt pathways was dissected by assessing phosphorylation status of these kinases and caspase activity in the absence and presence of specific inhibitors (SB431542, PD0325901 and LY294002), respectively. Results: TGF-β1 treatment suppressed FasL-mediated fibroblasts apoptosis with a greater than threefold reduction of caspase-3 activity (from 894 ± 186 to 195 ± 56 nmol AFC/min/106 cells at 250 ng/mL of FasL) and reductions in cleaved caspase-8 and caspase-3 by 3.2-fold and 4.3-fold, respectively. The reduction in caspase activation was accompanied by a decrease in annexin V-positive cells by ~80%. TGF-β1 treatment phosphorylated Smad2/3, Erk1/2 and Akt, which were reduced by their selective inhibitors. Inhibition of Smad2/3 and Erk1/2 alone partially reduced the protective effect of TGF-β1 on caspase-3 activation, whereas inhibition of the Akt pathway had no significant effect. Concomitant inhibition of Smad2/3 and Erk1/2 completely reversed the protection by TGF-β1. Conclusions: TGF-β1-mediated suppression of apoptosis in fibroblasts involves both Smad2/3 and Erk1/2 pathways, but not the Akt pathway. A combined approach inhibiting Smad2/3 and Erk1/2 pathways can completely reverse the protective effect of TGF-β1 on apoptosis. These findings are proof of concept to help define strategies to reduce progression of fibrosis and resultant morbidities associated with conditions causing excessive fibrosis, including but not limited to keloid formation, transplant fibrosis and aging-associated fibrosis of the heart.

The increasing prevalence of stroke, with an estimated annual cost of $71.5 billion, has made it a major health problem that increases disability and death, particularly in patients with atrial fibrillation. Although advanced age and atrial fibrillation are recognized as strong risk factors for stroke, the basis for this susceptibility are not well defined. Aging or associated diseases are accompanied by changes in rheostatic, humoral, metabolic and hemodynamic factors that may contribute more to stroke predisposition than rhythm abnormality alone. Several thromboembolism-predisposing clinical characteristics and serum biomarkers with prognostic significance have been identified in patients with atrial fibrillation. Although anticoagulation decreases the risk of thromboembolism, management in the elderly remains complex due to major concerns about bleeding. New anticoagulants and nonpharmacologic strategies are helpful to reduce the risk of bleeding, particularly in older-elderly patients. Herein, we review the pathogenesis and management of select issues of thromboembolism in the elderly with atrial fibrillation.

The aging human population has emerged as a critically important factor in health care, not only due to the unique physiologic and pathologic processes associated with aging but also because of the evolution of medical and surgical therapies that have increased quality and quantity of life. Heart failure is a disease found most commonly among older populations in whom it is associated with high morbidity and mortality. Heart failure disproportionately affects the elderly, and it stands to reason that the most terminal stage, known as advanced heart failure (AHF), is more common among the elderly. Despite limited data, treatment options for AHF patients, including heart transplantation and left ventricular assist device (LVAD) therapy, have demonstrated improved quality and quantity of life. Similarly, a well-structured palliative care program may offer symptom relief and social support without the need for high-risk surgical options. Furthermore, as the therapeutic window (risk/benefit ratio) is narrower among elderly patients, the potential for positive outcomes from AHF options must be carefully evaluated together with patient-specific risks in the context of palliative care discussions. Therefore, the decision to leverage these options must be balanced with not only age, but also frailty, comorbidities, and cognition, functional, social and nutritional status to determine the right candidates for each therapy. This review strives to inform providers on the relevant considerations when leveraging AHF options among elderly patients. We conclude by providing a personalized model for care developed at a large tertiary care hospital that has performed more than 1,600 AHF procedures (870 heart transplants, 745 LVADs).

Purpose: Outcomes in patients with atrial fibrillation who develop acute mesenteric ischemia, and the impact of anticoagulation on complications, are not defined. Methods: Patients admitted with acute mesenteric ischemia in the National Inpatient Sample from 2007, with and without atrial fibrillation, were compared for in-hospital outcomes using multivariate regression, and the impact of prior anticoagulation determined. Results: Of 48,872 patients with acute mesenteric ischemia, 8,306 had atrial fibrillation, with 680 patients also on anticoagulation. Atrial fibrillation patients were more likely to be older and have hypertension, heart failure, or chronic lung or renal disease. After adjusting for potential confounders, atrial fibrillation remained independently associated with higher mortality (P < 0.001). Patients on anticoagulation were less likely to have intestinal resections or shock, less likely to need intubation and had lesser hospital stay and hospital charges compared to those not on anticoagulation. Conclusions: In patients with acute mesenteric ischemia, presence of atrial fibrillation increases mortality, but prior anticoagulation reduces incidence of complications, length of stay and hospital charges.

Purpose: Access site complications following peripheral vascular intervention (PVI) are associated with prolonged hospitalization and increased mortality. Prediction of access site complication risk may optimize PVI care; however, there is no tool designed for this. We aimed to create a clinical scoring tool to stratify patients according to their risk of developing access site complications after PVI. Methods: The Society for Vascular Surgery’s Vascular Quality Initiative database yielded 27,997 patients who had undergone PVI at 131 North American centers. Clinically and statistically significant preprocedural risk factors associated with in-hospital, post-PVI access site complications were included in a multivariate logistic regression model, with access site complications as the outcome variable. A predictive model was developed with a random sample of 19,683 (70%) PVI procedures and validated in 8,314 (30%). Results: Access site complications occurred in 939 (3.4%) patients. The risk tool predictors are female gender, age > 70 years, white race, bedridden ambulatory status, insulin-treated diabetes mellitus, prior minor amputation, procedural indication of claudication, and nonfemoral arterial access site (model c-statistic = 0.638). Of these predictors, insulin-treated diabetes mellitus and prior minor amputation were protective of access site complications. The discriminatory power of the risk model was confirmed by the validation dataset (c-statistic = 0.6139). Higher risk scores correlated with increased frequency of access site complications: 1.9% for low risk, 3.4% for moderate risk and 5.1% for high risk. Conclusions: The proposed clinical risk score based on eight preprocedural characteristics is a tool to stratify patients at risk for post-PVI access site complications. The risk score may assist physicians in identifying patients at risk for access site complications and selection of patients who may benefit from bleeding avoidance strategies.

As the number of individuals, particularly the elderly, using herbal products with prescription drugs continues to grow, the risk for adverse interactions increases but remains poorly recognized. The true incidence and nature of adverse herb reactions or herb-drug interactions remains unknown since no postmarketing surveillance mechanism exists. Adverse events are greatly underreported, and information regarding safety mainly comes from case reports and suboptimally conducted studies in a limited number of healthy young volunteers or patients with limited comorbidities. Therefore, convincing evidence for the safety of herbal products in the elderly is lacking, and the true magnitude of problems that herb-drug interactions pose to public health, particularly in elderly patients with cardiovascular diseases, is not known. Since cardiovascular diseases themselves are life threatening, necessitate use of multiple medications and occur in a population with extensive comorbidities, the risk of herb-drug and herb-disease interactions is not minor and cannot be ignored. This review addresses these concerns in an effort to raise awareness about the use of herbal medicine by the elderly and its potential adverse impact on the efficacy of prescription medications that can increase predisposition to catastrophic events such as major bleeding, inadequate anticoagulation leading to undesired clotting, transplant organ rejection and life-threatening cardiac arrhythmias.

The guest editor introduces this specialty issue of the Journal of Patient-Centered Research and Reviews, which focuses on cardiovascular diseases in the elderly. The reality of an aging population has increased the need for better evidence-based medicine in older patients. However, randomized controlled trials frequently exclude such patients, especially those with comorbidities, from study. This practice ignores the fact that physiologic changes to the cardiovascular system caused by the aging process and aging-associated diseases create clinical dilemmas distinct from those in younger patients. Considering the rising costs of health care and growing incidence of cardiovascular disease, research efforts and resources need to be directed efficiently toward reducing overall disease burden and disability by focusing on prevention and early detection of disease in elderly patients.

Over 1,500 gene mutations are known to cause hypertrophic cardiomyopathy (HCM). Previous studies suggest that cardiac β-myosin heavy chain (MYH7) gene mutations are commonly associated with a more severe phenotype, compared to cardiac myosin binding protein-C (MYBPC3) gene mutations with milder phenotype, incomplete penetrance and later age of onset. Compound mutations can worsen the phenotype. This study aimed to validate these comparative differences in a large cohort of individuals and families with HCM. We performed genome-phenome correlation among 80 symptomatic HCM patients, 35 asymptomatic carriers and 35 non-carriers, using an 18-gene clinical diagnostic HCM panel. A total of 125 mutations were identified in 14 genes. MYBPC3 and MYH7 mutations contributed to 50.0% and 24.4% of the HCM patients, respectively, suggesting that MYBPC3 mutations were the most frequent cause of HCM in our cohort. Double mutations were found in only nine HCM patients (7.8%) who were phenotypically indistinguishable from single-mutation carriers. Comparisons of clinical parameters of MYBPC3 and MYH7 mutants were not statistically significant, but asymptomatic carriers had high left ventricular ejection fraction and diastolic dysfunction when compared to non-carriers. The presence of double mutations increases the risk for symptomatic HCM with no change in severity, as determined in this study subset. The pathologic effects of MYBPC3 and MYH7 were found to be independent of gene mutation location. Furthermore, HCM pathology is independent of protein domain disruption in both MYBPC3 and MYH7. These data provide evidence that MYBPC3 mutations constitute the preeminent cause of HCM and that they are phenotypically indistinguishable from HCM caused by MYH7 mutations.

Integration of mitochondria with cytosolic ATP-consuming/ATP-sensing and substrate supply processes is critical for muscle bioenergetics and electrical activity. Whether age-dependent muscle weakness and increased electrical instability depends on perturbations in cellular energetic circuits is unknown. To define energetic remodeling of aged atrial myocardium we tracked dynamics of ATP synthesis-utilization, substrate supply, and phosphotransfer circuits through adenylate kinase (AK), creatine kinase (CK), and glycolytic/glycogenolytic pathways using 18O stable isotope-based phosphometabolomic technology. Samples of intact atrial myocardium from adult and aged rats were subjected to 18O-labeling procedure at resting basal state, and analyzed using the 18O-assisted HPLC-GC/MS technique. Characteristics for aging atria were lower inorganic phosphate Pi[18O], γ-ATP[18O], β-ADP[18O], and creatine phosphate CrP[18O] 18O-labeling rates indicating diminished ATP utilization-synthesis and AK and CK phosphotransfer fluxes. Shift in dynamics of glycolytic phosphotransfer was reflected in the diminished G6P[18O] turnover with relatively constant glycogenolytic flux or G1P[18O] 18O-labeling. Labeling of G3P[18O], an indicator of G3P-shuttle activity and substrate supply to mitochondria, was depressed in aged myocardium. Aged atrial myocardium displayed reduced incorporation of 18O into second (18O2), third (18O3), and fourth (18O4) positions of Pi[18O] and a lower Pi[18O]/γ-ATP[18 O]-labeling ratio, indicating delayed energetic communication and ATP cycling between mitochondria and cellular ATPases. Adrenergic stress alleviated diminished CK flux, AK catalyzed β-ATP turnover and energetic communication in aging atria. Thus, 18O-assisted phosphometabolomics uncovered simultaneous phosphotransfer through AK, CK, and glycolytic pathways and G3P substrate shuttle deficits hindering energetic communication and ATP cycling, which may underlie energetic vulnerability of aging atrial myocardium.

Cytokine-dependent activation of fibroblasts to myofibroblasts, a key event in fibrosis, is accompanied by phenotypic changes with increased secretory and contractile properties dependent on increased energy utilization, yet changes in the energetic profile of these cells are not fully described. We hypothesize that the TGF-β1-mediated transformation of myofibroblasts is associated with an increase in mitochondrial content and function when compared to naive fibroblasts.Cultured NIH/3T3 mouse fibroblasts treated with TGF-β1, a profibrotic cytokine, or vehicle were assessed for transformation to myofibroblasts (appearance of α-smooth muscle actin [α-SMA] stress fibers) and associated changes in mitochondrial content and functions using laser confocal microscopy, Seahorse respirometry, multi-well plate reader and biochemical protocols. Expression of mitochondrial-specific proteins was determined using western blotting, and the mitochondrial DNA quantified using Mitochondrial DNA isolation kit.Treatment with TGF-β1 (5 ng/mL) induced transformation of naive fibroblasts into myofibroblasts with a threefold increase in the expression of α-SMA (6.85 ± 0.27 RU) compared to cells not treated with TGF-β1 (2.52 ± 0.11 RU). TGF-β1 exposure increased the number of mitochondria in the cells, as monitored by membrane potential sensitive dye tetramethylrhodamine, and expression of mitochondria-specific proteins; voltage-dependent anion channels (0.54 ± 0.05 vs. 0.23 ± 0.05 RU) and adenine nucleotide transporter (0.61 ± 0.11 vs. 0.22 ± 0.05 RU), as well as mitochondrial DNA content (530 ± 12 μg DNA/106 cells vs. 307 ± 9 μg DNA/106 cells in control). TGF-β1 treatment was associated with an increase in mitochondrial function with a twofold increase in baseline oxygen consumption rate (2.25 ± 0.03 vs. 1.13 ± 0.1 nmol O2/min/106 cells) and FCCP-induced mitochondrial respiration (2.87 ± 0.03 vs. 1.46 ± 0.15 nmol O2/min/106 cells).TGF-β1 induced differentiation of fibroblasts is accompanied by energetic remodeling of myofibroblasts with an increase in mitochondrial respiration and mitochondrial content.

Sleep apnea has been recognized as a factor predisposing to atrial fibrillation recurrence and progression. The effect of other sleep-disturbing conditions on atrial fibrillation progression is not known. We sought to determine whether frequent periodic leg movement during sleep is a risk factor for progression of atrial fibrillation. In this retrospective study, patients with atrial fibrillation and a clinical suspicion of restless legs syndrome who were referred for polysomnography were divided into two groups based on severity of periodic leg movement during sleep: frequent (periodic movement index >35/h) and infrequent (≤35/h). Progression of atrial fibrillation to persistent or permanent forms between the two groups was compared using Wilcoxon rank-sum test, chi-square tests and logistic regression analysis. Of 373 patients with atrial fibrillation (77% paroxysmal, 23% persistent), 108 (29%) progressed to persistent or permanent atrial fibrillation during follow-up (median, 33 months; interquartile range, 16-50). Compared to patients with infrequent periodic leg movement during sleep (n=168), patients with frequent periodic leg movement during sleep (n=205) had a higher rate of atrial fibrillation progression (23% vs. 34%; p=0.01). Patients with frequent periodic leg movement during sleep were older and predominantly male; however, there were no significant differences at baseline in clinical factors that promote atrial fibrillation progression between both groups. On multivariate analysis, independent predictors of atrial fibrillation progression were persistent atrial fibrillation at baseline, female gender, hypertension and frequent periodic leg movement during sleep. In patients with frequent periodic leg movement during sleep, dopaminergic therapy for control of leg movements in patients with restless legs syndrome reduced risk of atrial fibrillation progression. Frequent leg movement during sleep in patients with restless legs syndrome is associated with progression of atrial fibrillation to persistent and permanent forms.

Cardiac subsarcolemmal (SSM) and interfibrillar (IFM) mitochondrial subpopulations possess distinct biochemical properties and differ with respect to their protein and lipid compositions, capacities for respiration and protein synthesis, and sensitivity to metabolic challenge, yet their responsiveness to mitochondrially active cardioprotective therapeutics has not been characterized. This study assessed the differential responsiveness of the two mitochondrial subpopulations to diazoxide, a cardioprotective agent targeting mitochondria.Mitochondrial subpopulations were freshly isolated from rat ventricles and their morphologies assessed by electron microscopy and enzymatic activities determined using standard biochemical protocols with a plate reader. Oxidative phosphorylation was assessed from State 3 respiration using succinate as a substrate. Calcium dynamics and the status of Ca²⁺-dependent mitochondrial permeability transition (MPT) pore and mitochondrial membrane potential were assessed using standard Ca²⁺ and TPP⁺ ion-selective electrodes.Compared to IFM, isolated SSM exhibited a higher sensitivity to Ca²⁺ overload-mediated inhibition of adenosine triphosphate (ATP) synthesis with decreased ATP production (from 375±25 to 83±15 nmol ATP/min/mg protein in SSM, and from 875±39 to 583±45 nmol ATP/min/mg protein in IFM). In addition, SSM exhibited reduced Ca²⁺-accumulating capacity as compared to IFM (230±13 vs. 450±46 nmol Ca²⁺/mg protein in SSM and IFM, respectively), suggestive of increased Ca²⁺ sensitivity of MPT pore opening. Despite enhanced susceptibility to stress, SSM were more responsive to the protective effect of diazoxide (100 μM) against Ca²⁺ overload-mediated inhibition of ATP synthesis (67% vs. 2% in SSM and IFM, respectively).These results provide evidence for the distinct sensitivity of cardiac SSM and IFM toward Ca²⁺-dependent metabolic stress and the protective effect of diazoxide on mitochondrial energetics.