The Predictive Value of 2D Myocardial Strain for Epirubicin-Induced Cardiotoxicity

Preventing broken hearts in women with breast cancer: a concise review on chemotherapy-mediated cardiotoxicity

Cancer and cardiovascular disease are the leading causes of death for Canadian women. One in eight Canadian women will receive the life-changing diagnosis of breast cancer (BC) in their lifetime, with 1 in 34 dying from the disease. Although doxorubicin (DOX) and trastuzumab (TRZ) have significantly improved survival in women diagnosed with human epidermal growth factor receptor 2 (HER2)-positive BC, approximately one in four women who receive this treatment are at risk of developing chemotherapy-induced cardiotoxicity. Cardiotoxicity is defined as a decline in left ventricular ejection fraction (LVEF) of >10% to an absolute value of <53%. Current guidelines recommend the serial monitoring of LVEF in this patient population using non-invasive cardiac imaging modalities including transthoracic echocardiography or multi-gated acquisition scan; however, this will only allow for the detection of established cardiotoxicity. Recent studies have demonstrated that a reduction in global longitudinal strain by speckle tracking echocardiography can identify pre-clinical systolic dysfunction prior to a decline in overall LVEF. Implementation of early detection techniques would allow for the prompt initiation of cardioprotective strategies. In addition to the early detection of chemotherapy-mediated cardiotoxicity, the prophylactic use of angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, β-blockers, statins, exercise, and nutraceutical therapies have been studied in the setting of cardio-oncology.

Prevalence of cancer therapy cardiotoxicity as assessed by imaging procedures: A scoping review

BACKGROUND

Advances in treatment and optimization of chemotherapy protocols have greatly improved survival in cancer patients. Unfortunately, treatment can cause a reduction in left ventricular (LV) ejection fraction (EF) leading to cancer therapy-related cardiac dysfunction (CTRCD). We conducted a scoping review of published literature in order to identify and summarize the reported prevalence of cardiotoxicity evaluated by noninvasive imaging procedures in a wide-ranging of patients referred to cancer treatment as chemotherapy and/or radiation therapy.

METHODS

Different databases were checked (PubMed, Embase, and Web of Science) to identify studies published from January 2000 to June 2021. Articles were included if they reported data on LVEF evaluation in oncological patients treated with chemotherapeutic agents and/or radiotherapy, measured by echocardiography and/or nuclear or cardiac magnetic resonance imaging test, providing criteria of CTRCD evaluation such as the specific threshold for LVEF decrease.

RESULTS

From 963 citations identified, 46 articles, comprising 6841 patients, met the criteria for the inclusion in the scoping review. The summary prevalence of CTRCD as assessed by imaging procedures in the studies reviewed was 17% (95% confidence interval, 14-20).

CONCLUSIONS

The results of our scoping review endorse the recommendations regarding imaging modalities to ensure identification of cardiotoxicity in patients undergoing cancer therapies. However, to improve patient management, more homogeneous CTRCD evaluation studies are required, reporting a detailed clinical assessment of the patient before, during and after treatment.

A global case meta-analysis of three-dimensional speckle tracking for evaluating the cardiotoxicity of anthracycline chemotherapy in breast cancer

Background

Anthracycline cardiotoxicity has become one of the most common complications of anthracycline therapy. Regular follow-up of chemotherapy patients with myocardial deformation parameters might be helpful for early diagnosis of myocardial damage and protective intervention. This study aimed to investigate the value of three-dimensional speckle tracking imaging (3D-STI) in diagnosing and predicting potential cardiotoxicity in breast cancer patients undergoing anthracycline therapy through meta-analysis based on global cases collection.

Methods

Relevant case-control studies published prior to November 2021 were extracted to assess cardiotoxicity by 3D-STI in breast cancer patients undergoing chemotherapy. Weighted mean difference (WMD) and 95% confidence interval (CI) were used as pooled statistics. Meta regression and subgroup analysis were employed to identify sources of heterogeneity and publication bias was evaluated by Egger’s test and funnel plot.

Results

A total of 1,515 breast cancer patients from 14 studies were enrolled and followed up for 4 or 6 cycles of chemotherapy. Following chemotherapy, absolute values of Left ventricular ejection fraction (LVEF) WMD = –1.59, 95% CI (–1.99, –1.20); p < 0.001; global longitudinal strain (GLS) WMD = 2.19, 95% CI (1.87, 2.51); p < 0.001; global circumferential strain (GCS) WMD = 1.69, 95% CI (1.11, 2.26); p < 0.001; global radial strain (GRS) WMD = –1.72,95% CI (–2.44, –1.00); p < 0.001, and global area strain (GAS) WMD = 6.25, 95% CI (4.48, 8.02); p < 0.001 were decreased. A medium degree of heterogeneity was shown for values of LVEF (I² = 44.4%, p = 0.037) while values for GLS (I² = 59.0%, p = 0.003), GCS (I² = 81.3%, p < 0.001) and GRS (I² = 57.5%, P = 0.004) showed a large degree of heterogeneity. Egger’s test and funnel plot showed no significant publication bias in GLS, GCS and GAS data (all p > 0.05).

Conclusion

3D-STI has utility for the non-invasive and objective evaluation of changes in left ventricular function in breast cancer patients undergoing chemotherapy with anthracyclines. The current findings have clinical potential for the early evaluation of myocardial injury caused by chemotherapy toxicity.

POLRMT as a Novel Susceptibility Gene for Cardiotoxicity in Epirubicin Treatment of Breast Cancer Patients

Anthracyclines are among the most used chemotherapeutic agents in breast cancer (BC). However their use is hampered by anthracycline-induced cardiotoxicity (AIC). The currently known clinical and genetic risk factors do not fully explain the observed inter-individual variability and only have a limited ability to predict which patients are more likely to develop this severe toxicity. To identify novel predictive genes, we conducted a two-stage genome-wide association study in epirubicin-treated BC patients. In the discovery phase, we genotyped over 700,000 single nucleotide variants in a cohort of 227 patients. The most interesting finding was rs62134260, located 4kb upstream of POLRMT (OR = 5.76, P = 2.23 × 10-5). We replicated this association in a validation cohort of 123 patients (P = 0.021). This variant regulates the expression of POLRMT, a gene that encodes a mitochondrial DNA-directed RNA polymerase, responsible for mitochondrial gene expression. Individuals harbouring the risk allele had a decreased expression of POLRMT in heart tissue that may cause an impaired capacity to maintain a healthy mitochondrial population in cardiomyocytes under stressful conditions, as is treatment with epirubicin. This finding suggests a novel molecular mechanism involved in the development of AIC and may improve our ability to predict patients who are at risk.