Radiation-induced Heart Disease Research Articles

SP-0349 Radiation-induced heart disease in the era of CT-based treatment planning of early breast cancer

SP-0349 Radiation-induced heart disease in the era of CT-based treatment planning of early breast cancer

Radiation-induced ischemic heart disease

Radiation therapy is a widely used treatment for malignant neoplasms of the chest. Radiation-related cardiovascular disease is associated with significant morbidity and mortality. This review discusses the diagnosis and treatment of radiation-induced coronary artery disease. The most common indications for radiotherapy to the mediastinal region are Hodgkin's lymphoma and breast cancer. Hodgkin's lymphoma is one of the most common forms of malignant neoplasms in young people, with an estimated incidence of 3 per 100 000 population and a 10-year survival rate of more than 80%. The incidence of radiation-induced coronary heart disease is about 60% among survivors with Hodgkin's lymphoma 40 years after radiation therapy, and the risk of coronary heart disease and myocardial infarction is 3.2 and 2 times higher, respectively, compared to the general population. Breast cancer is the most common form of malignant neoplasm among women. In 2017, a meta-analysis was published evaluating the effect of radiation therapy for breast cancer on the risk of coronary heart disease and cardiac death. Radiation therapy for breast cancer was associated with an increase in the absolute risk of 76.4 (95% CI 36.8–130.5) cases of coronary heart disease and 125.5 (95% CI 98.8–157.9) cases cardiac death per 100 000 person-years. The risk began to increase during the first decade for death from coronary heart disease and from the second decade for overall death from cardiovascular disease. There is a time lag between exposure to radiation therapy and the development of coronary artery disease. In survivors of Hodgkin's lymphoma, the average time to develop coronary artery disease can range from 2 to 40 years, and in patients with breast cancer, about 9–10 years. Risk factors for radiation-induced coronary artery disease include age at the time of radiation therapy, total radiation dose, amount of tissue exposed, and lack of cardiac shielding techniques.

Altered DNA Methylation and Gene Expression Profiles in Radiation-Induced Heart Fibrosis of Sprague-Dawley Rats.

Radiation-induced heart disease (RIHD) is a serious side effect of radiotherapy for thoracic tumors. Advanced myocardial fibrosis in the late phase of RIHD can lead to myocardial remodeling, heart function impairing and heart failure, resulting in serious clinical consequences, and its pathogenesis remains vague. DNA methylation is one of the important epigenetic mechanisms which often occurs in response to environmental stimuli and is crucial in regulating gene expression. We hypothesized DNA methylation may contribute to pathogenesis in radiation-induced heart fibrosis (RIHF) and altered DNA methylation patterns probably influenced the genes expression in RIHF. In present study, we found genome-wide differences in DNA methylation status and RNA expression were demonstrated and we screened out 44 genes whose altered expression maybe were regulated by CpG island methylation within the gene promoter in RIHF of Sprague-Dawley rat by employing gene expression arrays and human CpG island microarrays. Gene expression and CpG island methylation levels of several candidate genes were further validated. Our investigation provided a new dimension to reveal the specific mechanisms of RIHF and explore the potential therapeutic targets for it.

Synthetic contrast-enhanced computed tomography generation using a deep convolutional neural network for cardiac substructure delineation in breast cancer radiation therapy: a feasibility study

BackgroundAdjuvant radiation therapy improves the overall survival and loco-regional control in patients with breast cancer. However, radiation-induced heart disease, which occurs after treatment from incidental radiation exposure to the cardiac organ, is an emerging challenge. This study aimed to generate synthetic contrast-enhanced computed tomography (SCECT) from non-contrast CT (NCT) using deep learning (DL) and investigate its role in contouring cardiac substructures. We also aimed to determine its applicability for a retrospective study on the substructure volume-dose relationship for predicting radiation-induced heart disease.MethodsWe prepared NCT-CECT cardiac scan pairs of 59 patients. Of these, 35, 4, and 20 pairs were used for training, validation, and testing, respectively. We adopted conditional generative adversarial network as a framework to generate SCECT. SCECT was validated in the following three stages: (1) The similarity between SCECT and CECT was evaluated; (2) Manual contouring was performed on SCECT and CECT with sufficient intervals and based on this, the geometric similarity of cardiac substructures was measured between them; (3) The treatment plan was quantitatively analyzed based on the contours of SCECT and CECT.ResultsWhile the mean values (± standard deviation) of the mean absolute error, peak signal-to-noise ratio, and structural similarity index measure between SCECT and CECT were 20.66 ± 5.29, 21.57 ± 1.85, and 0.77 ± 0.06, those were 23.95 ± 6.98, 20.67 ± 2.34, and 0.76 ± 0.07 between NCT and CECT, respectively. The Dice similarity coefficients and mean surface distance between the contours of SCECT and CECT were 0.81 ± 0.06 and 2.44 ± 0.72, respectively. The dosimetry analysis displayed error rates of 0.13 ± 0.27 Gy and 0.71 ± 1.34% for the mean heart dose and V5Gy, respectively.ConclusionOur findings displayed the feasibility of SCECT generation from NCT and its potential for cardiac substructure delineation in patients who underwent breast radiation therapy.

Momordica. charantia-Derived Extracellular Vesicles-Like Nanovesicles Protect Cardiomyocytes Against Radiation Injury via Attenuating DNA Damage and Mitochondria Dysfunction.

Thoracic radiotherapy patients have higher risks of developing radiation-induced heart disease (RIHD). Ionizing radiation generates excessive reactive oxygens species (ROS) causing oxidative stress, while Momordica. charantia and its extract have antioxidant activity. Plant-derived extracellular vesicles (EVs) is emerging as novel therapeutic agent. Therefore, we explored the protective effects of Momordica. charantia-derived EVs-like nanovesicles (MCELNs) against RIHD. Using density gradient centrifugation, we successfully isolated MCELNs with similar shape, size, and markers as EVs. Confocal imaging revealed that rat cardiomyocytes H9C2 cells internalized PKH67 labeled MCELNs time-dependently. In vitro assay identified that MCELNs promoted cell proliferation, suppressed cell apoptosis, and alleviated the DNA damage in irradiated (16 Gy, X-ray) H9C2 cells. Moreover, elevated mitochondria ROS in irradiated H9C2 cells were scavenged by MCELNs, protecting mitochondria function with re-balanced mitochondria membrane potential. Furthermore, the phosphorylation of ROS-related proteins was recovered with increased ratios of p-AKT/AKT and p-ERK/ERK in MCELNs treated irradiated H9C2 cells. Last, intraperitoneal administration of MCELNs mitigated myocardial injury and fibrosis in a thoracic radiation mice model. Our data demonstrated the potential protective effects of MCELNs against RIHD. The MCELNs shed light on preventive regime development for radiation-related toxicity.

Internal Mammary Node Irradiation in Patients With Node-Positive Early Breast Cancer: Fifteen-Year Results From the Danish Breast Cancer Group Internal Mammary Node Study.

The Danish Breast Cancer Group Internal Mammary Node study demonstrated improved 8-year overall survival (OS) with internal mammary node irradiation (IMNI) in patients with node-positive early breast cancer. Here, we present long-term results from the Danish Breast Cancer Group Internal Mammary Node study cohort. This nationwide, prospective cohort study allocated patients with node-positive early breast cancer to adjuvant radiotherapy with or without IMNI depending on cancer laterality. Patients with right-sided cancer received IMNI. Patients with left-sided cancer were treated without IMNI because of risk of radiation-induced heart disease. Other treatment was independent of laterality. The primary study end point was OS. Secondary end points were distant recurrence and breast cancer mortality. Analyses were by intention to treat. During 2003-2007, 3,089 women were allocated to IMNI (right-sided, n = 1,491) or no IMNI (left-sided, n = 1,598). With a median follow-up of 14.8 years, 589 patients with and 701 patients without IMNI had died. The corresponding 15-year OS rates were 60.1% and 55.4%. The adjusted hazard ratio (HR) for death was 0.86 (95% CI, 0.77 to 0.96; P = .007) in favor of IMNI. The 15-year risk of developing distant recurrence was 35.6% (523 recurrences) and 38.6% (602 recurrences) with vs. without IMNI (adjusted HR, 0.88 [95% CI, 0.79 to 0.99; P = .04]). The 15-year breast cancer mortality with IMNI was 31.7% (467 deaths) compared with 33.9% (537 deaths) without IMNI (adjusted HR, 0.88 [95% CI, 0.78 to 1.00; P = .05]). The distribution of other deaths was similar across groups. In patients with node-positive early breast cancer treated with IMNI or without IMNI depending on breast cancer laterality, IMNI reduced the risk of distant recurrence and death from breast cancer, thereby improving long-term survival.

MicroRNA-223-3p Protect Against Radiation-Induced Cardiac Toxicity by Alleviating Myocardial Oxidative Stress and Programmed Cell Death via Targeting the AMPK Pathway.

Objectives: Radiotherapy improves the survival rate of cancer patients, yet it also involves some inevitable complications. Radiation-induced heart disease (RIHD) is one of the most serious complications, especially the radiotherapy of thoracic tumors, which is characterized by cardiac oxidative stress disorder and programmed cell death. At present, there is no effective treatment strategy for RIHD; in addition, it cannot be reversed when it progresses. This study aims to explore the role and potential mechanism of microRNA-223-3p (miR-223-3p) in RIHD. Methods: Mice were injected with miR-223-3p mimic, inhibitor, or their respective controls in the tail vein and received a single dose of 20 Gy whole-heart irradiation (WHI) for 16 weeks after 3 days to construct a RIHD mouse model. To inhibit adenosine monophosphate activated protein kinase (AMPK) or phosphodiesterase 4D (PDE4D), compound C (CompC) and AAV9-shPDE4D were used. Results: WHI treatment significantly inhibited the expression of miR-223-3p in the hearts; furthermore, the levels of miR-223-3p decreased in a radiation time-dependent manner. miR-223-3p mimic significantly relieved, while miR-223-3p inhibitor aggravated apoptosis, oxidative damage, and cardiac dysfunction in RIHD mice. In addition, we found that miR-223-3p mimic improves WHI-induced myocardial injury by activating AMPK and that the inhibition of AMPK by CompC completely blocks these protective effects of miR-223-3p mimic. Further studies found that miR-223-3p lowers the protein levels of PDE4D and inhibiting PDE4D by AAV9-shPDE4D blocks the WHI-induced myocardial injury mediated by miR-223-3p inhibitor. Conclusion: miR-223-3p ameliorates WHI-induced RIHD through anti-oxidant and anti-programmed cell death mechanisms via activating AMPK by PDE4D regulation. miR-223-3p mimic exhibits potential value in the treatment of RIHD.

Dosimetric Comparison of the Heart and Left Anterior Descending Artery in Patients With Left Breast Cancer Treated With Three-Dimensional Conformal and Intensity-Modulated Radiotherapy.

BackgroundAdjuvant radiotherapy plays an important role in the management of breast cancer, along with surgery and chemotherapy. However, postoperative radiotherapy poses an increased risk of radiation-induced heart diseases in patients with left-sided breast cancer due to damage of the coronary arteries, which can cause myocardial fibrosis and coronary artery disease; however, there is a lack of sufficient evidence for it. Hence, the present study aimed to assess the dosimetric parameters of the heart and left anterior descending (LAD) coronary artery in patients with left breast cancer treated with three-dimensional conformal radiotherapy (3DCRT) and intensity-modulated radiotherapy (IMRT).MethodologyThis study included 20 patients with left-sided breast cancer treated between January and July 2019. Patients were equally divided into two groups as follows: group I included those treated with 3DCRT and group II included those treated with IMRT. Radiotherapy was administered to the chest wall and regional lymph nodes. The dose administered for the planning target volume was 50 Gy in 25 daily fractions over five weeks with 6 MV photons. Dosimetric parameters of planning tumor volume (PTV; V95%, V90%, Dmax, Dmin, Dmean, V53.5 Gy, conformity index, and homogeneity index) along with the heart (V5%, V30%, and Dmean) and LAD artery (mean and V25%) were evaluated. Dose-volume histograms were generated and compared. The LAD artery was contoured virtually retrospectively during the study to determine the dosimetric parameters; the dose to the LAD artery was not considered during planning.ResultsDosimetric parameters of the PTV were similar for 3DCRT and IMRT; D95 (38.53 vs. 41.61 Gy), D90 (43.67 vs. 44.77 Gy), Dmean (48.3 vs. 48.72 Gy), conformity index (1.10 vs. 1.06), and homogeneity index (0.50 and 0.28) did not show a significant difference. The Dmean for the LAD artery was significantly higher than that for the heart on 3DCRT (23.66 Gy vs. 8.46 Gy; p < 0.0000) and IMRT (31.53 vs. 17.7 Gy; p < 0.0000). The V25 for the LAD artery was significantly higher than that for the heart on 3DCRT (40.27 vs. 14.13 Gy; p < 0.0024) and IMRT (66.21 vs. 27.74 Gy; p < 0.0002).ConclusionsRadiation doses to the LAD artery and heart must be evaluated prior to radiotherapy in patients with left breast cancer. Long-term follow-up is needed to evaluate cardiac complications and their association with dosimetric parameters.

Small animal models of localized heart irradiation.

A subset of cancer patients treated with radiation therapy may experience radiation-induced heart disease (RIHD) that develops within weeks to several years after cancer treatment. Rodent models are most commonly used to examine the biological effects of local X-rays in the heart and test potential strategies to reduce RIHD. While developments in technology over the last decades have changed the procedures for local heart irradiation in animal models, the X-ray settings and radiation doses have remained quite consistent in time and between different research laboratories. This chapter provides a protocol for whole heart irradiation in rodent models, using an X-ray machine with cone beam computed tomography (CBCT) capabilities. Some methods for the quantification of common histological changes after whole heart irradiation in the rodent are also described.

RADIATION-INDUCED DAMAGE TO THE CARDIOVASCULAR SYSTEM AFTER RADIATION THERAPY IN WOMEN WITH BREAST CANCER.

Despite current research in the development of drugbased cytostatic and targeted therapies in the treatment of breast cancer, radiation therapy (RT) is an important component in the treatment of this pathology in the postoperative period. At the same time, an important problem is the development of pathological changes in the heart in the longterm period, which worsen the quality of life and increase the risk of cardiac death 10 or more years after RT The problem of heart damage due to RT is gaining new significance due to the existing increase in the number of cancer patients requiring radiation exposure in the modern world. RT of malignant tumors of the breast and organs of the chest cavity causes damage to all structures of the heart, including the coronary arteries, valves, conducting system, pericardium. The frequency of heart damage increases in proportion to the time that has passed after RT. According to some authors, the prevalence of clinically significant radiationinduced heart diseases 5-10 years after RT is 10-30%, and the frequency of asymptomatic lesions is 88%. The duration of the latent period can reach 15-20 years. The work has an analysis of longterm studies of the presence of pathological changes that are found in the heart tissues of patients with breast cancer, as a result of radiation therapy.

Activation of Neural Modeling-Related Genes in the Heart of Mice after Gamma Irradiation.

Objective Radiation-induced heart disease (RIHD) is a common sequela of thoracic irradiation. At the same time, nerve remodeling is involved in the progression of heart disease. However, the activation of the nerve remodeling related genes in radiation-induced heart disease is still lacking. Methods In this study, C57BL/J mice was anesthetized by intraperitoneal injection with pentobarbital sodium (2%, 40 mg/kg), and radiation was delivered using a cobalt-60 (60Co) teletherapy unit (Cirus). When the mice were anesthetized, none of them showed the signs of peritonitis, pain, or discomfort. The mice hearts were exposed to a γ-radiation field of 5 mm × 5 mm. The total dose of γ-radiation was 3 Gy/day for each animal for 5 consecutive days. The mice were executed by severed neck, and its limbs were weak. Quantitative Polymerase Chain Reaction (qPCR) and immunohistochemistry were used to explore the possible mechanism of arrhythmia in patients with RIHD. Results Our results demonstrated that Growth-Associated Protein 43 (GAP43) was increased significantly after radioactive heart injury compared with the control group. Moreover, the protein expression of Tyrosine hydroxylase (TH) and Choline acetyl-transferase (CHAT) was significantly decreased compared with the control group and gradually increased with time rend. The nerve growth factor (NGF) was remarkably increased after radiation-induced heart injury compared with the control group. Immunohistochemistry results indicated that the nerve growth factors GAP43 and NGF were significantly increased after radiation-induced heart injury. Conclusions Chest radiotherapy could activate the neural modeling related genes in RIHD. This may provide a new treatment plan for the future treatment of heart problems caused by chest radiotherapy.

Radiation-Induced Heart Disease.

Cancer incidence and survivorship have had a rising tendency over the last two decades due to better treatment modalities. One of these is radiation therapy (RT), which is used in 20–55% of cancer patients, and its basic principle consists of inhibiting proliferation or inducing apoptosis of cancer cells. Classically, photon beam RT has been the mainstay therapy for these patients, but, in the last decade, proton beam has been introduced as a new option. This newer method focuses more on the tumor and affects less of the surrounding normal tissue, i.e., the heart. Radiation to the heart is a common complication of RT, especially in patients with lymphoma, breast, lung, and esophageal cancer. The pathophysiology is due to changes in the microvascular and macrovascular milieu that can promote accelerated atherosclerosis and/or induce fibrosis of the myocardium, pericardium, and valves. These complications occur days, weeks, or years after RT and the risk factors associated are high radiation doses (>30 Gy), concomitant chemotherapy (primarily anthracyclines), age, history of heart disease, and the presence of cardiovascular risk factors. The understanding of these mechanisms and risk factors by physicians can lead to a tailored assessment and monitorization of these patients with the objective of early detection or prevention of radiation-induced heart disease. Echocardiography is a noninvasive method which provides a comprehensive evaluation of the pericardium, valves, myocardium, and coronaries, making it the first imaging tool in most cases; however, other modalities, such as computed tomography, nuclear medicine, or cardiac magnetic resonance, can provide additional value.

Initial experience of the implementation of a cardio-oncology program for breast cancer patients receiving modern radiotherapy in a tertiary institution

Background: The modern era of multimodality cancer treatment strategies has contributed to a much longer survival time of breast cancer patients. Accordingly, cardiovascular toxicity related to anticancer therapy including radiation-induced heart disease has become an issue of concern. To address this issue, it is important to develop cardio-oncology programs to provide cardiovascular assessment, surveillance and management for patients receiving cancer therapy with potential heart impairment.

Investigation of the Antihypertrophic and Antifibrotic Effects of Losartan in a Rat Model of Radiation-Induced Heart Disease.

Radiation-induced heart disease (RIHD) is a potential late side-effect of thoracic radiotherapy resulting in left ventricular hypertrophy (LVH) and fibrosis due to a complex pathomechanism leading to heart failure. Angiotensin-II receptor blockers (ARBs), including losartan, are frequently used to control heart failure of various etiologies. Preclinical evidence is lacking on the anti-remodeling effects of ARBs in RIHD, while the results of clinical studies are controversial. We aimed at investigating the effects of losartan in a rat model of RIHD. Male Sprague-Dawley rats were studied in three groups: (1) control, (2) radiotherapy (RT) only, (3) RT treated with losartan (per os 10 mg/kg/day), and were followed for 1, 3, or 15 weeks. At 15 weeks post-irradiation, losartan alleviated the echocardiographic and histological signs of LVH and fibrosis and reduced the overexpression of chymase, connective tissue growth factor, and transforming growth factor-beta in the myocardium measured by qPCR; likewise, the level of the SMAD2/3 protein determined by Western blot decreased. In both RT groups, the pro-survival phospho-AKT/AKT and the phospho-ERK1,2/ERK1,2 ratios were increased at week 15. The antiremodeling effects of losartan seem to be associated with the repression of chymase and several elements of the TGF-β/SMAD signaling pathway in our RIHD model.

Abstract 17189: Radiation-induced Accelerated Multi-valve Disease In A Patient With Subaortic Membrane

A 69-year-old woman with history of right breast cancer status post lumpectomy and radiation (4.2 cGy) 18 months prior, presented with progressive NYHA class III dyspnea. TTE obtained prior to her cancer diagnosis was notable for normal LV size and wall thickness, a subaortic membrane with systolic mean Doppler gradient of 21 mmHg and a mildly thickened mitral valve without significant stenosis or regurgitation. On presentation, TTE was notable for severely increased concentric LV wall thickness (LV mass index 140 g/m 2 ), preserved ejection fraction, increased RV wall thickness, subaortic stenosis with systolic mean Doppler gradient 35 mmHg, moderate-severe aortic regurgitation, thickened mitral valve with posterior leaflet tethering and anterior leaflet override causing severe mitral regurgitation and moderate mitral stenosis (valve area 1.7 cm 2 by pressure half-time). She underwent a surgical intervention with septal myectomy, subaortic membrane resection, aortic root reconstruction, aortic and mitral valve replacement with bioprostheses. She did well post-operatively and had complete resolution of symptoms following cardiac rehabilitation. Radiation-induced valvular heart disease is linked to the total dose of radiation, use of sequential chemotherapy and time since irradiation, with a typical latency of 10-20 years. However, there is paucity of data regarding the influence of these variables in patients with pre-existing valve disease. This case illustrates dramatic acceleration of underlying aortic and mitral valve pathology in a patient with a subaortic membrane, 18 months after radiation. We also noted development of significant concentric LV hypertrophy that was disproportionate to the degree of obstruction across the sub-aortic membrane. Potential candidates for radiation therapy must be carefully screened for pre-existing valve disease, which should warrant increased vigilance and early screening for progressive valve disease.

Abstract 9422: Assessment of Cardiotoxicity Following Thoracic Radiotherapy and Systemic Stem-Cell Derived Extracellular Vesicle Treatments

Introduction: Radiotherapeutic management of certain cancers provides distinct benefits, but also results in variable degrees of cardiac exposure. Resultant radiation-induced heart disease (RIHD) typically manifests at protracted post-irradiation times and can involve a wide range of underlying pathologies including heart failure. Past work from our lab has identified an intervention involving systemic administration of human embryonic stem cell (hESC) derived extracellular vesicles (EV) shown to resolve radiation-induced lung disease (RILD). However, potential treatment-associated complications to the heart were not investigated. Hypothesis: In this study, we hypothesized that 1) radiation would cause a certain level of heart dysfunction, and 2) that stem cell-derived EV would not further confound RIHD. Methods: Separate cohorts of control (no radiation +/- EV) and treated (radiation +/- EV) mice were implemented in this study. For the treatment groups, mice were subjected to a single dose of image guided thoracic irradiation (14 Gy) and then systemically injected with hESC-derived EV at different time points. Echocardiography was performed in 4 cohorts (n=46); control arm (n=9), radiation alone arm (n=24), EV alone arm (no radiation) (n=5) and toxicity control arm involving 4 EV doses at weeks 0, 1, 2, 3) (n=8). The following parameters were compared between the 4 cohorts: E/A ratio, ejection fraction (EF), shortening fraction (SF), left ventricular mass (LV mass), end diastolic volume (EDV). Results: Radiation caused statistically significant lower E/A ratios compared with mice that did not receive radiation, with non-significant changes in other key indicators of cardiac function. Importantly, EV treatments had no effect on E/A ratio or any other indices of cardiac function among the different cohorts. Conclusions: Irradiated mice had lower E/A ratios but EF was unchanged, suggesting that thoracic exposures compromised diastolic function without impacting EF. Diastolic dysfunction was most likely linked to increased radiation-induced fibrosis and myocardium stiffness. Importantly, EV treatments were not observed to adversely impact cardiac function, pointing to the safety of this potential intervention for RILD.

Exercise Enhanced Cardiac Function in Mice With Radiation-Induced Heart Disease via the FNDC5/Irisin-Dependent Mitochondrial Turnover Pathway.

Background: Despite the development of radiation therapy (RT) techniques, concern regarding the serious and irreversible heart injury induced by RT has grown due to the lack of early intervention measures. Although exercise can act as an effective and economic nonpharmacologic strategy to combat fatigue and improve quality of life for cancer survivors, limited data on its application in radiation-induced heart disease (RIHD) and the underlying molecular mechanism are available.Methods: Fifteen young adult male mice were enrolled in this study and divided into 3 groups (including exercised RIHD group, sedentary RIHD group, and controls; n =5 samples/group). While the mice in the control group were kept in cages without irradiation, those in the exercised RIHD group underwent 3weeks of aerobic exercise on the treadmill after radiotherapy. At the end of the 3rd week following RT, FNDC5/irisin expression, cardiac function, aerobic fitness, cardiomyocyte apoptosis, mitochondrial function, and mitochondrial turnover in the myocardium were assessed to identify the protective role of exercise in RIHD and investigate the potential mechanism.Results: While sedentary RIHD group had impaired cardiac function and aerobic fitness than controls, the exercised RIHD mice had improved cardiac function and aerobic fitness, elevated ATP production and the mitochondrial protein content, decreased mitochondrial length, and increased formation of mitophagosomes compared with sedentary RIHD mice. These changes were accompanied by the elevated expression of FNDC5/irisin, a fission marker (DRP1) and mitophagy markers (PINK1 and LC3B) in exercised RIHD group than that of sedentary RIHD group, but the expression of biogenesis (TFAM) and fusion (MFN2) markers was not significantly changed.Conclusion: Exercise could enhance cardiac function and aerobic fitness in RIHD mice partly through an autocrine mechanism via FNDC5/irisin, in which autophagy was selectively activated, suggesting that FNDC5/irisin may act as an intervening target to prevent the development of RIHD.

Cardiologic Long-Term Follow-Up of Patients Treated With Chest Radiotherapy: When and How?

Introduction: Radiotherapy may cause valvular (VHD), pericardial, coronary artery disease (CAD), left ventricular dysfunction (LVD), arrhythmias. The risk of radiation induced heart disease (RIHD) increases over time. The current guidelines suggest a screening for RIHD every 5 years in the long-term survivors who had been treated by chest RT.Methods: We reviewed the clinical and instrumental data of 106 patients diagnosed with RIHD. In one group (Group A: 69 patients) RIHD was diagnosed in an asymptomatic phase through a screening with ECG, echocardiogram and stress test. A second group (37 patients) was seen when RIHD was symptomatic. We compared the characteristics of the two groups at the time of RT, of RIHD detection and at last follow-up.Results: Overall, 64 patients (60%) had CAD (associated to other RIHD in 18); 39 (36.7%) had LVD (isolated in 20); 24 (22.6%) had VHD (isolated in 10 cases). The interval between the last negative test and the diagnosis of moderate or severe RIHD was <5 years in 26 patients, and <4 years in 18. In group A, 63% of the patients with CAD had silent ischemia. The two groups did not differ with regard to type of tumor, cardiovascular risk factors, use of anthracycline-based chemotherapy, age at RT treatment, radiation dose and interval between RT and toxicity detection. The mean time from RT and RIHD was 16 years in group A and 15 in group B. Interventional therapy at RIHD diagnosis was more frequent in group B (54 vs. 30%, p < 0.05). At last follow-up, 27 patients had died (12 of cancer, 9 of cardiac causes, 6 of other causes); mean ejection fraction was 60% in group A and 50% in group B (p < 0.01). Patients with ejection fraction ≤ 50% were 14.5% in group A and 40% in group B (p < 0.01).Conclusions: Clinically relevant RIHD become evident at a mean interval of 16 years after RT. The most frequent clinical manifestations are CAD and LVD. RIHD diagnosis in asymptomatic patients may preserve their cardiac function with timely interventions. We suggest -after 10 years from radiotherapy- a screening every 2–3 years.

Early In Vivo Detection of Radiation-Induced Cardiotoxicity With Hyperpolarized C-13 Pyruvate Magnetic Resonance Spectroscopy

Radiation therapy is commonly used for treatment of patients with intrathoracic malignancies, such as lung cancer, esophageal cancer, and lymphoma. Radiation-Induced Heart Disease (RIHD) is a major source of morbidity and mortality in patients receiving thoracic radiation. Therefore, there is an acute need for development of non-invasive approaches for detection of RIHD at a stage that offers potential for early intervention and reversibility. Cardiac mitochondrial dysfunction is a hallmark of radiation-induced cardiac injury. During aerobic respiration, pyruvate enters the tricarboxylic acid cycle and is metabolized into bicarbonate in mitochondria. We hypothesized that radiation-induced mitochondrial dysfunction results in decreased conversion of pyruvate to bicarbonate in the mitochondria and increased conversion to lactate in cytosol. We sought to non-invasively assess radiation-induced changes in mitochondrial myocardial metabolism by tracking the fate of hyperpolarized (HP) C-13 pyruvate utilization using Magnetic Resonance Spectroscopy (MRS).Sprague-Dawley rats (n = 10) underwent baseline echocardiography and HP C-13 pyruvate MRS. Rats in the cardiac radiation group (n = 5) underwent image-guided cardiac radiation with cone-beam CT, to a total dose of 40 Gy in 5 fractions. All rats underwent repeat echocardiography and hyperpolarized C-13 pyruvate MRS one week later.For the first time, we have demonstrated feasibility of employing HP C-13 pyruvate MRS for detecting radiation-induced myocardial mitochondrial metabolic changes in a pre-clinical rat model. In the cardiac radiation group, C-13 pyruvate MRS demonstrated a statistically significant decrease in cardiac bicarbonate-to-lactate ratio compared to pre-radiation baseline (P = 0.02, one-tailed paired t-test), suggesting increased metabolism of pyruvate into lactate in the cytoplasm (at the expense of metabolism into bicarbonate in the mitochondria) due to mitochondrial dysfunction. No significant decrease in this ratio was observed in the non-irradiated, age matched controls (P = 0.90). No significant changes in left ventricular ejection fraction or global longitudinal strain were observed in either the cardiac irradiation or control group of rats at this time point.Radiation-induced myocardial mitochondrial dysfunction is an early event and can be detected in vivo by hyperpolarized C-13 pyruvate MRS within 1 week after radiation, and prior to onset of echocardiographic changes. Due to its non-invasive nature, this technology has the potential to serve as a platform for building radiation-focused cardio-oncology programs for early detection and mitigation of radiation-induced cardiac injury in hundreds of thousands of patients receiving thoracic radiation annually.

No changes in myocardial perfusion following radiation therapy of left-sided breast cancer: A positron emission tomography study

BackgroundAdjuvant radiation therapy (RT) for breast cancer has improved overall survival. However, incidental exposure of the heart has been linked to development of radiation-induced heart disease. The aim of this study was, in a cohort of asymptomatic post-irradiation breast cancer patients, to investigate changes in myocardial blood flow (MBF) and presence of perfusion defects in myocardial perfusion positron-emission-tomography (PET) in the irradiated myocardium. Methods and ResultsTwenty patients treated with RT for left-sided breast cancer underwent 13N-ammonia myocardial perfusion PET 7(± 2) years after breath adapted RT to a total dose of 48 Gy given in 24 fractions. No differences in rest or stress MBF were noted between the irradiated and non-irradiated myocardium (1.29 (± 0.29) vs 1.33 (± 0.29) mL/g/min, ns; 2.74 (± 0.59) vs 2.78 (± 0.66) mL/g/min, ns, respectively). One patient demonstrated a myocardial perfusion defect localized in the irradiated anterior wall myocardium. ConclusionAlthough limited by a small sample size, early signs of cardiac injury detected by NH3 myocardial perfusion PET was at least not frequent in our cohort of patients treated with a modern RT technique for left-sided breast cancer, even 7 years after treatment. The findings however, may not rule out subsequent development of myocardial injury.