Cardiac-Specific Inactivation of LPP3 in Mice Leads to Myocardial Dysfunction and Heart Failure

Lipid Phosphate phosphatase 3 (LPP3), encoded by the Plpp3 gene, is an enzyme that dephosphorylates the bioactive lipid mediator lysophosphatidic acid (LPA). To study the role of LPP3 in the myocardium, we generated a cardiac specific Plpp3 deficient mouse strain. Although these mice were viable at birth in contrast to global Plpp3 knockout mice, they showed increased mortality ~ 8 months. LPP3 deficient mice had enlarged hearts with reduced left ventricular performance as seen by echocardiography. Cardiac specific Plpp3 deficient mice had longer ventricular effective refractory periods compared to their Plpp3 littermates. We observed that lack of Lpp3 enhanced cardiomyocyte hypertrophy based on analysis of cell surface area. We found that lack of Lpp3 signaling was mediated through the activation of Rho and phospho-ERK pathways. There are increased levels of fetal genes Natriuretic Peptide A and B (Nppa and Nppb) expression indicating myocardial dysfunction. These mice also demonstrate mitochondrial dysfunction as evidenced by a significant decrease (P \u3c 0.001) in the basal oxygen consumption rate, mitochondrial ATP production, and spare respiratory capacity as measured through mitochondrial bioenergetics. Histology and transmission electron microscopy of these hearts showed disrupted sarcomere organization and intercalated disc, with a prominent disruption of the cristae and vacuole formation in the mitochondria. Our findings suggest that LPA/LPP3-signaling nexus plays an important role in normal function of cardiomyocytes

Total sulfane sulfur bioavailability reflects ethnic and gender disparities in cardiovascular disease

Hydrogen sulfide (H2S) has emerged as an important physiological and pathophysiological signaling molecule in the cardiovascular system influencing vascular tone, cytoprotective responses, redox reactions, vascular adap- tation, and mitochondrial respiration. However, bioavailable levels of H2S in its various biochemical metabolite forms during clinical cardiovascular disease remain poorly understood. We performed a case-controlled study to quantify and compare the bioavailability of various biochemical forms of H2S in patients with and without cardiovascular disease (CVD). In our study, we used the reverse-phase high performance liquid chromatography monobromobimane assay to analytically measure bioavailable pools of H2S. Single nucleotide polymorphisms (SNPs) were also identified using DNA Pyrosequencing. We found that plasma acid labile sulfide levels were significantly reduced in Caucasian females with CVD compared with those without the disease. Conversely, plasma bound sulfane sulfur levels were significantly reduced in Caucasian males with CVD compared with those without the disease. Surprisingly, gender differences of H2S bioavailability were not observed in African Americans, although H2S bioavailability was significantly lower overall in this ethnic group compared to Caucasians. We also performed SNP analysis of H2S synthesizing enzymes and found a significant increase in cystathionine gamma-lyase (CTH) 1364 G-T allele frequency in patients with CVD compared to controls. Lastly, plasma H2S bioavailability was found to be predictive for cardiovascular disease in Caucasian subjects as de- termined by receiver operator characteristic analysis. These findings reveal that plasma H2S bioavailability could be considered a biomarker for CVD in an ethnic and gender manner. Cystathionine gamma-lyase 1346 G-T SNP might also contribute to the risk of cardiovascular disease development

SOD2 Deficiency in Cardiomyocytes Defines Defective Mitochondrial Bioenergetics as a Cause of Lethal Dilated Cardiomyopathy

Electrophilic aldehyde (4-hydroxynonenal; 4-HNE), formed after lipid peroxidation, is a mediator of mitochondrial dysfunction and implicated in both the pathogenesis and the progression of cardiovascular disease. Manganese superoxide dismutase (MnSOD), a nuclear-encoded antioxidant enzyme, catalyzes the dismutation of superoxide radicals (O2•-) in mitochondria. To study the role of MnSOD in the myocardium, we generated a cardiomyocyte-specific SOD2 (SOD2Δ) deficient mouse strain. Unlike global SOD2 knockout mice, SOD2Δ mice reached adolescence; however, they die at ~4 months of age due to heart failure. Ultrastructural analysis of SOD2Δ hearts revealed altered mitochondrial architecture, with prominent disruption of the cristae and vacuole formation. Noninvasive echocardiographic measurements in SOD2Δ mice showed dilated cardiomyopathic features such as decreased ejection fraction and fractional shortening along with increased left ventricular internal diameter. An increased incidence of ventricular tachycardia was observed during electrophysiological studies of the heart in SOD2Δ mice. Oxidative phosphorylation (OXPHOS) measurement using a Seahorse XF analyzer in SOD2Δ neonatal cardiomyocytes and adult cardiac mitochondria displayed reduced O2 consumption, particularly during basal conditions and after the addition of FCCP (H+ ionophore/uncoupler), compared to that in SOD2fl hearts. Measurement of extracellular acidification (ECAR) to examine glycolysis in these cells showed a pattern precisely opposite that of the oxygen consumption rate (OCR) among SOD2Δ mice compared to their SOD2fl littermates. Analysis of the activity of the electron transport chain complex identified a reduction in Complex I and Complex V activity in SOD2Δ compared to SOD2fl mice. We demonstrated that a deficiency of SOD2 increases reactive oxygen species (ROS), leading to subsequent overproduction of 4-HNE inside mitochondria. Mechanistically, proteins in the mitochondrial respiratory chain complex and TCA cycle (NDUFS2, SDHA, ATP5B, and DLD) were the target of 4-HNE adduction in SOD2Δ hearts. Our findings suggest that the SOD2 mediated 4-HNE signaling nexus may play an important role in cardiomyopathy

Kv1.1 potassium channel subunit deficiency alters ventricular arrhythmia susceptibility, contractility, and repolarization

Epilepsy-associated Kv1.1 voltage-gated potassium channel subunits encoded by the Kcna1 gene have traditionally been considered absent in heart, but recent studies reveal they are expressed in cardiomyocytes where they could regulate intrinsic cardiac electrophysiology. Although Kv1.1 now has a demonstrated functional role in atria, its role in the ventricles has never been investigated. In this work, electrophysiological, histological, and gene expression approaches were used to explore the consequences of Kv1.1 deficiency in the ventricles of Kcna1 knockout (KO) mice at the organ, cellular, and molecular levels to determine whether the absence of Kv1.1 leads to ventricular dysfunction that increases the risk of premature or sudden death. When subjected to intracardiac pacing, KO mice showed normal baseline susceptibility to inducible ventricular arrhythmias (VA) but resistance to VA under conditions of sympathetic challenge with isoproterenol. Echocardiography revealed cardiac contractile dysfunction manifesting as decreased ejection fraction and fractional shortening. In whole-cell patch-clamp recordings, KO ventricular cardiomyocytes exhibited action potential prolongation indicative of impaired repolarization. Imaging, histological, and transcript analyses showed no evidence of structural or channel gene expression remodeling, suggesting that the observed deficits are likely electrogenic due to Kv1.1 deficiency. Immunoblots of patient heart samples detected the presence of Kv1.1 at relatively high levels, implying that Kv1.1 contributes to human cardiac electrophysiology. Taken together, this work describes an important functional role for Kv1.1 in ventricles where its absence causes repolarization and contractility deficits but reduced susceptibility to arrhythmia under conditions of sympathetic drive

Prognostic value of Cardiac Biomarkers in COVID-19 Infection: A Meta-analysis

Multiple Biomarkers have recently been shown to be elevated in COVID-19, a respiratory infection with multi-organ dysfunction; however, information regarding the prognostic value of cardiac biomarkers as it relates to disease severity and cardiac injury are inconsistent. The goal of this meta-analysis was to summarize the evidence regarding the prognostic relevance of cardiac biomarkers from data available in published reports. PubMed was searched from inception through April 2020 for studies comparing median values of cardiac biomarkers in critically ill versus non-critically ill COVID-19 patients, or patients who died versus those who survived. The weighted mean differences (WMD) and 95% confidence interval (CI) between the groups were calculated for each study and combined using a random effects meta-analysis model. The odds ratio (OR) for mortality based on cardiac injury was combined from studies reporting it. Troponin levels were significantly higher in COVID-19 patients who died or were critically ill versus those who were alive or not critically ill (WMD 0.58, 95% CI 0.42-0.71, p\u3c0.001). Cardiac injury was independently associated with significantly increased odds of mortality (OR 6.641, 95% CI 1.26 - 35.1, p=0.03). No difference in BNP was seen between the two groups. A significant difference in levels of D-dimer was seen in those who died or were critically ill. CK levels were only significantly higher in those who died versus those who were alive (WMD 0.47 95% CI 0.09-0.84, p=0.014). Cardiac biomarkers add prognostic value to the determination of the severity of COVID-19 and can predict mortality

Utility of recognizing early electrocardiogram changes in bronchogenic Takotsubo cardiomyopathy: A case report

BACKGROUND: Takotsubo cardiomyopathy (TCM) is a transient reversible systolic dysfunction, estimated to be the culprit in 1%-2% of patients presenting with clinical symptoms of acute coronary syndrome (ACS). TCM was previously thought to be indistinguishable from ACS on the basis of electrocardiogram (EKG) findings; many authors now describe specific EKG changes that distinguish TCM from ACS as well as aid in early recognition of TCM. CASE SUMMARY: This unique case presentation illustrates an uncommon subtype of TCM, and very clearly exemplifies the specific EKG changes meant to aid in distinguishing TCM from ACS. A bronchogenic subtype of TCM has been proposed, given its prevalence and distinguishing features from TCM without pulmonary pathology; this case exemplifies that notion. The specific EKG changes of low QRS voltage and attenuation of the amplitude of the QRS complex are now being noted in the EKGs of TCM patients. This patient presented for worsening shortness of breath and increased productive cough; her EKG revealed ST elevations in leads V3-V6, and low voltage QRS complexes when compared to previous EKG from 12 wk ago; troponin peaked at 5.16 ng/mL. Left heart catheterization did not reveal significant lesions and left ventriculogram findings were consistent with TCM. Patient was treated for COPD exacerbation, her symptoms improved significantly; she was sent home on the appropriate medications. CONCLUSION: This case exemplifies EKG changes noted in TCM patients who may aid in early detection and appropriate treatment of TCM

Survival Benefit of Aspirin in Patients With Congestive Heart Failure: A Meta-Analysis

BACKGROUND: There is no clear consensus on the use of aspirin (ASA) in patients with congestive heart failure (CHF) due to its reported interaction with other cardio-prudent medications. The aim was to evaluate the effect of ASA on all-cause mortality and the frequency of hospitalization for heart failure in patients with CHF using meta-analysis, as well as to study the potential variables interacting with this effect. METHODS: Eligible studies were identified via a PubMed search, the related article feature and a manual search of references. Studies were included if they had a study population with CHF of any etiology, compared ASA to no ASA or placebo, and reported one or both of the following outcomes: 1) all-cause mortality and 2) the frequency of hospitalization for heart failure. Data were extracted and verified. We used the inverse variance method in a random-effects model to combine effect sizes. RESULTS: A total of 14 studies with a combined study population of 64,550 patients were included in the final analysis. All-cause mortality was found to be significantly lower in patients who were taking ASA (P = 0.003). When examining the use of ASA, no significant difference was found in the frequency of hospitalization for heart failure. ASA use was demonstrated to be more beneficial against mortality in studies with a larger percentage of patients on nitrates (P = 0.008) and oral anticoagulants (P = 0.04). A significantly lower rate of hospitalization for heart failure was observed in patients who used oral anticoagulants and ASA concurrently (P = 0.02). CONCLUSIONS: ASA may have beneficial effects on mortality in patients with heart failure of all etiologies

Adverse events related to AtriCure EPi-Sense Coagulation Device-Analysis of the FDA MAUDE database

INTRODUCTION: The AtriCure EPi-Sense Device is used for the hybrid convergent procedure, an emerging treatment for persistent atrial fibrillation (AF) and long-standing persistent AF. However, data on the AE related to the EPi-Sense device are scarce. METHODS: Keyword EPI-SENSE was searched on the MAUDE database. There were 80 device reports from 2016 to 2020. After excluding reports when the device was not returned for evaluation, 79 device reports were included for final analysis. RESULTS: The adverse events (AE) were broadly classified into 11 categories. The most common complications were pericardial effusion (25.3%), stroke (17.7%), and atrioesophageal fistula (AEF) (8.9%). Death was reported in 15 (19%) cases, 3 of which were due to pulmonary embolism, 6 due to AEF, 3 due to unknown cause, 1 due to sepsis, 2 due to events related to acute renal failure. DISCUSSION: Pericardial effusion is a common AE reported in patients with convergence procedures and is well documented in the CONVERGE trial. The convergent procedure is unique in that the epicardial ablations are performed on the posterior wall with the radiofrequency probe directed towards the heart and away from the esophagus which in theory should reduce esophageal injuries. Despite that, a high number of AEF were noticed. Finally, there were also some reports of saline perfusion malfunction which can lead to injuries due to overheating. CONCLUSION: This analysis of the AE related to the EPi-Sense device highlights several major AE that are previously unreported