Early Detection of Cardiac Damage by Two-Dimensional Speckle Tracking Echocardiography After Thoracic Radiation Therapy: Study Protocol for a Prospective Cohort Study

Cardiotoxicity prevention in thoracic radiotherapy: The effect of different melatonin doses on the level of oxidation markers -in vivo animal study

Introduction

Radiation-induced cardiotoxicity (RIC) is a significant adverse effect of thoracic radiotherapy (RT), leading to oxidative stress, inflammation, endothelial dysfunction, myocardial fibrosis, vascular damage, and cardiac dysfunction. Melatonin (MLT), a potent antioxidant and radioprotective agent, has been suggested to mitigate these effects. This study aims to evaluate the optimal dosage of MLT for cardioprotection following RT in a rat model.

Materials and methods

Forty-five adult male Sprague-Dawley rats were divided into five groups. The control group received 1 mL saline solution and sham irradiation. The RT-only group received 12 Gy RT in a single fraction with saline. Three experimental groups received the same RT dose with MLT at 100 mg/kg, 50 mg/kg, or 5 mg/kg. Eight weeks post-irradiation, protein oxidation, lipid peroxidation, glycoxidation, non-enzymatic redox homeostasis biomarkers, and histological changes in heart tissues were examined.

Results

In MLT-treated groups, 5 mg/kg dose was found to be more effective in preventing protein oxidation and lipid peroxidation. The levels of advanced glycation end products were significantly lower in 5 mg/kg and 50 mg/kg MLT groups compared to the RT only group, whereas no difference was found at the high dose (100 mg/kg). When Cu-Zn superoxide dismutase activity, iron ion reducing antioxidant power and total thiol groups were evaluated, we found that 5 mg/kg MLT caused a significant increase in these antioxidant parameters, while 50 mg/kg and 100 mg/kg dose caused significant increase in superoxide dismutase. Evaluation heart tissues showed that the RIC was significantly lower in all MLT-treated groups.

Conclusion

5 mg/kg melatonin reduces oxidative markers and RIC in rats, indicating its potential as a low-dose cardioprotective agent after RT.

Quantitative evaluation of radiation-induced heart disease in beagle dogs by speckle tracking echocardiography

OBJECTIVE

This study aimed to detect early changes in left ventricular systolic function in Beagle dogs after radiotherapy using two-dimensional speckle tracking echocardiography and to explore its potential value in evaluating radiation-induced heart disease.

METHODS

Thirty-six Beagle dogs were randomized into a control group (n = 18) and an irradiation group (n = 18). The irradiation group received a single dose of 20 Gy to the left ventricular anterior wall, while controls underwent sham irradiation. Conventional echocardiography and 2D speckle tracking echocardiography were performed at baseline and 3, 6, and 12 months post-procedure. Additionally, six dogs were randomly selected from each group and euthanized at 3-, 6-, and 12-month post-irradiation, and their hearts were collected for histopathological testing.

RESULTS

In the irradiation group, the global longitudinal strain of the left ventricle and regional strain in the irradiated area were significantly reduced versus baseline and controls by 3 months, with progressive decline at 6 and 12 months. Strain reduction correlated spatially with pathological injury. Conversely, there were no substantial differences in conventional echocardiographic parameters between the groups after 3 months. Conventional parameters (e.g., LVEF) showed differences only at later timepoints. Histopathology revealed progressive cardiomyocyte damage, fibrosis, and microvascular injury in irradiated regions, extending to the posterior wall by 12 months.

CONCLUSION

Two-dimensional speckle tracking echocardiography-derived strain parameters spatially correlate with radiation-induced pathological changes and detect subtle systolic dysfunction prior to irreversible remodeling. Speckle tracking may localize regions of peak radiation dose delivery.

Deep Inspiratory Breath-Hold Technique for Patients with Left-Sided Breast Cancer: Dosimetric Analysis, Clinical Evaluation, and Prediction

IntroductionBreast radiotherapy is associated with a higher risk of cardiac diseases. Although deep inspiration breath-hold (DIBH) reduces the heart dose, it is underutilized. The selection of proper candidates for DIBH remains an unresolved issue. This study compared dosimetric parameters between free breathing (FB) and DIBH, monitored myocardial enzymes, and aimed to identify factors that can predict cardiac injury thus developing a method to identify proper patients for DIBH.MethodsThis is a prospective cohort study, enrolling 58 patients with left-sided breast cancer following breast-conserving surgery. All patients underwent computed tomography scans in both FB and DIBH states. A comparative analysis of dosimetric features between DIBH and FB was conducted. Myocardial enzyme was monitored until six months post-radiation therapy. T-tests were used to assess differences between the DIBH and the FB. Pearson correlation and receiver operating characteristic (ROC) analysis was conducted to identify factors associated with the subclinical acute cardiac injury.ResultsThe mean heart dose (MHD) of the DIBH group significantly dropped as compared to the FB group (3.81 Gy vs 1.65 Gy p = 0.001). Cardiac V40, V30, V25, V10, and V5 volumes also significantly reduced. 9(15.51%) patients exhibited increased myocardial enzyme, with cTnI being the most sensitive indicator. The heart dose was a predictor for the cardiac enzyme's elevation. The ROC curve analysis revealed an area under the curve of 0.6. With an MHD threshold of 2 Gy, both sensitivity and specificity exceeded 0.7.ConclusionDIBH significantly diminishes radiation exposure to the heart and LAD compared with FB. Cardiac enzyme analysis facilitates the early detection of cardiac injury following radiation therapy. An MHD threshold of less than 2 Gy is associated with a reduced risk of subclinical cardiac injury, potentially obviating the need for DIBH, which optimizes clinical efficiency and economic viability.

Characteristics and research status among clinical trials in cardio-oncology by bibliometric and visualized analysis

BACKGROUND

We aim to establish the characteristics of published cardio-oncology research of clinical trials by bibliometric analysis and to talk about the prospects and difficulties facing the development of cardio-oncology.

METHODS

Search of data related to clinical trials in cardiac oncology from 1990 to 2022 from the Web of Science core collection. Using CiteSpace to perform co-citation analysis of authors, countries (regions) and institutions, journals and cited journals, cited authors and cited literature, and keywords.

RESULTS

Of the 607 clinical trial studies, the number of papers published per year has increased over time. The regions with the greatest influence were North America (especially the United States) and Europe. Multicenter research has always been the focus of cardio-oncology research, but cross-regional cooperation was still lacking. Myocardial toxicity caused by anthracyclines has received the earliest attention and has been studied for the longest time. Meanwhile, the efficacy and cardiotoxicity of new anticancer drugs always came into focus, but at a slow pace. Few studies on myocardial toxicity were related to the treatment of tumors except breast cancer. Risk factors, heart disease, adverse outcomes, follow-up, and intervention protection were the major hotspots revealed by co-citation cluster.

CONCLUSIONS

There is great potential for the development of clinical trials in cardio-oncology, especially in multicenter cooperation across different regions. Expansion of tumor types, myocardial toxicity of different drugs, and effective interventions in the research direction and design of clinical trials are necessary.

Preclinical models of radiation-induced cardiac toxicity: Potential mechanisms and biomarkers

Radiation therapy (RT) is an important modality in cancer treatment with >50% of cancer patients undergoing RT for curative or palliative intent. In patients with breast, lung, and esophageal cancer, as well as mediastinal malignancies, incidental RT dose to heart or vascular structures has been linked to the development of Radiation-Induced Heart Disease (RIHD) which manifests as ischemic heart disease, cardiomyopathy, cardiac dysfunction, and heart failure. Despite the remarkable progress in the delivery of radiotherapy treatment, off-target cardiac toxicities are unavoidable. One of the best-studied pathological consequences of incidental exposure of the heart to RT is collagen deposition and fibrosis, leading to the development of radiation-induced myocardial fibrosis (RIMF). However, the pathogenesis of RIMF is still largely unknown. Moreover, there are no available clinical approaches to reverse RIMF once it occurs and it continues to impair the quality of life of long-term cancer survivors. Hence, there is an increasing need for more clinically relevant preclinical models to elucidate the molecular and cellular mechanisms involved in the development of RIMF. This review offers an insight into the existing preclinical models to study RIHD and the suggested mechanisms of RIMF, as well as available multi-modality treatments and outcomes. Moreover, we summarize the valuable detection methods of RIHD/RIMF, and the clinical use of sensitive radiographic and circulating biomarkers.

Oncological Benefit versus Cardiovascular Risk in Breast Cancer Patients Treated with Modern Radiotherapy

Radiotherapy (RT) is an essential part of breast cancer (BC) treatments. Unfortunately, heart exposure to radiation can also impair the long-term survival of patients. Our study aimed to quantify the oncological benefit and the cardiovascular (CV) risk associated with modern RT in a real-world cohort of BC patients. Our descriptive study enrolled BC patients who received adjuvant RT. Ten-year overall survival (OS) was estimated using Predict^® version 2.1 (National Health Service, London, UK). The basal risk of CV events was estimated using the American Heart Association (ACC/AHA) CV score. Treatment volumes and mean cardiac doses were obtained from RT treatment plan records. The increased risk of CV events due to RT was estimated using a model proposed by Darby. The risk of acute myocardial infarction or stroke mortality was estimated using HeartScore^® (European Society of Cardiology, Brussels, Belgium). A total of 256 BC patients were included in the study. The average age of patients was 57 years old (range: 25–91); 49.6% had left BC. The mean cardiac dose was 166 cGy (interquartile range (IQR) 94–273); the estimated hazard ratio (HR) for CV disease was HR 1.12 (confidence interval (CI) 1.04–1.24). The estimated baseline 10-year CV risk was 5.6% (0.2 to 51.2); CV risk increased by 0.9% (range 0.02–35.47%) after RT. The absolute risk of 10-year mortality from CV disease was 2.5% (0.1–9); RT was associated with an estimated 4.9% survival benefit (3.73–6.07) against BC death and a 0.23% (0.17–0.29) estimated increase in CV mortality. Modern RT decreased 10-year BC mortality by 4% but increased CV mortality by 0.2% in this cohort. Our findings encourage the implementation of personalized adjuvant RT treatments that balance risks and benefits to improve long-term BC patient survival.