Contribution Of Impaired Myocardial Insulin Signaling To Mitochondrial Dysfunction And Oxidative Stress In The Heart

Background—Diabetes-associated cardiac dysfunction is associated with mitochondrial dysfunction and oxidative stress, which may contribute to LV dysfunction. The contribution of altered myocardial insulin action, independently of associated changes in systemic metabolism is incompletely understood. The present study tested the hypothesis that perinatal loss of insulin signaling in the heart impairs mitochondrial function. Methods and Results—In 8-week-old mice with cardiomyocyte deletion of insulin receptors (CIRKO), inotropic reserves were reduced and mitochondria manifested respiratory defects for pyruvate that was associated with proportionate reductions in catalytic subunits of pyruvate dehydrogenase. Progressive age-dependent defects in oxygen consumption and ATP synthesis with the substrates glutamate and the fatty acid derivative palmitoyl carnitine (PC) were observed. Mitochondria were also uncoupled when exposed to PC due in part to increased ROS production and oxidative stress. Although proteomic and genomic approaches revealed a reduction in subsets of genes and proteins related to oxidative phosphorylation, no reduction in maximal activities of mitochondrial electron transport chain complexes were found. However, a disproportionate reduction in TCA cycle and FA oxidation proteins in mitochondria, suggest that defects in FA and pyruvate metabolism and TCA flux may explain the mitochondrial dysfunction observed. Conclusions—Impaired myocardial insulin signaling promotes oxidative stress and mitochondrial uncoupling, which together with reduced TCA and FA oxidative capacity impairs mitochondrial energetics. This study identifies specific contributions of impaired insulin action to mitochondrial dysfunction in the heart

Ablation of PGC-1β Results in Defective Mitochondrial Activity, Thermogenesis, Hepatic Function, and Cardiac Performance

The transcriptional coactivator peroxisome proliferator-activated receptor-gamma coactivator-1β (PGC-1β) has been implicated in important metabolic processes. A mouse lacking PGC-1β (PGC1βKO) was generated and phenotyped using physiological, molecular, and bioinformatic approaches. PGC1βKO mice are generally viable and metabolically healthy. Using systems biology, we identified a general defect in the expression of genes involved in mitochondrial function and, specifically, the electron transport chain. This defect correlated with reduced mitochondrial volume fraction in soleus muscle and heart, but not brown adipose tissue (BAT). Under ambient temperature conditions, PGC-1β ablation was partially compensated by up-regulation of PGC-1α in BAT and white adipose tissue (WAT) that lead to increased thermogenesis, reduced body weight, and reduced fat mass. Despite their decreased fat mass, PGC1βKO mice had hypertrophic adipocytes in WAT. The thermogenic role of PGC-1β was identified in thermoneutral and cold-adapted conditions by inadequate responses to norepinephrine injection. Furthermore, PGC1βKO hearts showed a blunted chronotropic response to dobutamine stimulation, and isolated soleus muscle fibres from PGC1βKO mice have impaired mitochondrial function. Lack of PGC-1β also impaired hepatic lipid metabolism in response to acute high fat dietary loads, resulting in hepatic steatosis and reduced lipoprotein-associated triglyceride and cholesterol content. Altogether, our data suggest that PGC-1β plays a general role in controlling basal mitochondrial function and also participates in tissue-specific adaptive responses during metabolic stress

Maximal wall thickness measurement in hypertrophic cardiomyopathy

Objectives The aim of this study was to define the variability of maximal wall thickness (MWT) measurements across modalities and predict its impact on care in patients with hypertrophic cardiomyopathy (HCM). Background Left ventricular MWT measured by echocardiography or cardiovascular magnetic resonance (CMR) contributes to the diagnosis of HCM, stratifies risk, and guides key decisions, including whether to place an implantable cardioverter-defibrillator (ICD). Methods A 20-center global network provided paired echocardiographic and CMR data sets from patients with HCM, from which 17 paired data sets of the highest quality were selected. These were presented as 7 randomly ordered pairs (at 6 cardiac conferences) to experienced readers who report HCM imaging in their daily practice, and their MWT caliper measurements were captured. The impact of measurement variability on ICD insertion decisions was estimated in 769 separately recruited multicenter patients with HCM using the European Society of Cardiology algorithm for 5-year risk for sudden cardiac death. Results MWT analysis was completed by 70 readers (from 6 continents; 91% with >5 years’ experience). Seventy-nine percent and 68% scored echocardiographic and CMR image quality as excellent. For both modalities (echocardiographic and then CMR results), intramodality inter-reader MWT percentage variability was large (range –59% to 117% [SD ±20%] and –61% to 52% [SD ±11%], respectively). Agreement between modalities was low (SE of measurement 4.8 mm; 95% CI 4.3 mm-5.2 mm; r = 0.56 [modest correlation]). In the multicenter HCM cohort, this estimated echocardiographic MWT percentage variability (±20%) applied to the European Society of Cardiology algorithm reclassified risk in 19.5% of patients, which would have led to inappropriate ICD decision making in 1 in 7 patients with HCM (8.7% would have had ICD placement recommended despite potential low risk, and 6.8% would not have had ICD placement recommended despite intermediate or high risk). Conclusions Using the best available images and experienced readers, MWT as a biomarker in HCM has a high degree of inter-reader variability and should be applied with caution as part of decision making for ICD insertion. Better standardization efforts in HCM recommendations by current governing societies are needed to improve clinical decision making in patients with HCM

Cardiotoxicity of T-Cell Antineoplastic Therapies: JACC: CardioOncology Primer.

T-cell therapies, such as chimeric antigen receptor (CAR) T-cell, bispecific T-cell engager (BiTE) and tumor-infiltrating lymphocyte (TIL) therapies, fight cancer cells harboring specific tumor antigens. However, activation of the immune response by these therapies can lead to a systemic inflammatory response, termed cytokine release syndrome (CRS), that can result in adverse events, including cardiotoxicity. Retrospective studies have shown that cardiovascular complications occur in 10% to 20% of patients who develop high-grade CRS after CAR T-cell therapy and can include cardiomyopathy, heart failure, arrhythmias, and myocardial infarction. While cardiotoxicities have been less commonly reported with BiTE and TIL therapies, systematic surveillance for cardiotoxicity has not been performed. Patients undergoing T-cell therapies should be screened for cardiovascular conditions that may not be able to withstand the hemodynamic perturbations imposed by CRS. Generalized management of CRS, including the use of the interleukin-6 antagonist, tocilizumab, for high-grade CRS, is used to mitigate the risk of cardiotoxicity

Gender Differences in Diagnosis, Prevention, and Treatment of Cardiotoxicity in Cardio-Oncology

Gender differences exist throughout the medical field and significant progress has been made in understanding the effects of gender in many aspects of healthcare. The field of cardio-oncology is diverse and dynamic with new oncologic and cardiovascular therapies approved each year; however, there is limited knowledge regarding the effects of gender within cardio-oncology, particularly the impact of gender on cardiotoxicities. The relationship between gender and cardio-oncology is unique in that gender likely affects not only the biological underpinnings of cancer susceptibility, but also the response to both oncologic and cardiovascular therapies. Furthermore, gender has significant socioeconomic and psychosocial implications which may impact cancer and cardiovascular risk factor profiles, cancer susceptibility, and the delivery of healthcare. In this review, we summarize the effects of gender on susceptibility of cancer, response to cardiovascular and cancer therapies, delivery of healthcare, and highlight the need for further gender specific studies regarding the cardiovascular effects of current and future oncological treatments

Cardiovascular Imaging in Contemporary Cardio-Oncology: A Scientific Statement From the American Heart Association.

Advances in cancer therapeutics have led to dramatic improvements in survival, now inclusive of nearly 20 million patients and rising. However, cardiovascular toxicities associated with specific cancer therapeutics adversely affect the outcomes of patients with cancer. Advances in cardiovascular imaging have solidified the critical role for robust methods for detecting, monitoring, and prognosticating cardiac risk among patients with cancer. However, decentralized evaluations have led to a lack of consensus on the optimal uses of imaging in contemporary cancer treatment (eg, immunotherapy, targeted, or biological therapy) settings. Similarly, available isolated preclinical and clinical studies have provided incomplete insights into the effectiveness of multiple modalities for cardiovascular imaging in cancer care. The aims of this scientific statement are to define the current state of evidence for cardiovascular imaging in the cancer treatment and survivorship settings and to propose novel methodological approaches to inform the optimal application of cardiovascular imaging in future clinical trials and registries. We also propose an evidence-based integrated approach to the use of cardiovascular imaging in routine clinical settings. This scientific statement summarizes and clarifies available evidence while providing guidance on the optimal uses of multimodality cardiovascular imaging in the era of emerging anticancer therapies