Doxorubicin cardiotoxicity: prevention of congestive heart failure with serial cardiac function monitoring with equilibrium radionuclide angiocardiography in the current era

Serum biomarkers for the detection of cardiac toxicity after chemotherapy and radiation therapy in breast cancer patients

Multi-modality cancer treatments that include chemotherapy, radiation therapy, and targeted agents are highly effective therapies. Their use, especially in combination, is limited by the risk of significant cardiac toxicity. The current paradigm for minimizing cardiac morbidity, based on serial cardiac function monitoring, is suboptimal. An alternative approach based on biomarker testing, has emerged as a promising adjunct and a potential substitute to routine echocardiography. Biomarkers, most prominently cardiac troponins and natriuretic peptides, have been evaluated for their ability to describe the risk of potential cardiac dysfunction in clinically asymptomatic patients. Early rises in cardiac troponin concentrations have consistently predicted the risk and severity of significant cardiac events in patients treated with anthracycline-based chemotherapy. Biomarkers represent a novel, efficient, and robust clinical decision tool for the management of cancer therapy-induced cardiotoxicity. This article aims to review the clinical evidence that supports the use of established biomarkers such as cardiac troponins and natriuretic peptides, as well as emerging data on proposed biomarkers.

Assessment of an intermediate reprojection technique transitioning from planar to SPECT radionuclide ventriculography

BACKGROUND

The technique of SPECT-RNV (radionuclide ventriculography) offers a greater amount of clinically usable data than its planar counterpart (P-RNV). In transitioning from planar to SPECT-only acquisition methodologies, reprojection of the SPECT data can provide a planar dataset which can be used as an interim technique. The aim of this study was to test if reprojected planar images could be used as a surrogate for true planar images in SPECT-only setting.

METHODS

We performed SPECT-RNV and P-RNV on 47 patients on traditional sodium iodide (NaI) cameras, determining left ventricular ejection fractions (LVEF) for planar (EFP) and SPECT (EFS) techniques. We reprojected the SPECT-RNV data along the best septal separation angle determined from planar scanning. This creates a further planar dataset denoted 'reprojected P-RNV' (rP-RNV) giving a reprojected ejection fraction (EFR) which can be used as a validation variable in transitioning to SPECT-only acquisition.

RESULTS

Performing t tests showed no statistical difference between EFP and EFR (P > .017) but bias was observed in EFS results compared to EFP and EFS compared to EFR results. An unblinded, comparison of parametric data between the three datasets for a subset of ten patients showed good clinical concordance. False negative and false positive rates were low for rP-RNV compared to P-RNV.

CONCLUSIONS

The reprojected planar LVEF correlates well to P-RNV EF values. The rP-RNV dataset can aid clinicians in transitioning from planar RNV to SPECT-only acquisition.

Nuclear imaging in detection and monitoring of cardiotoxicity

Cardiotoxicity as a result of cancer treatment is a novel and serious public health issue that has a significant impact on a cancer patient’s management and outcome. The coexistence of cancer and cardiac disease in the same patient is more common because of aging population and improvements in the efficacy of antitumor agents. Left ventricular dysfunction is the most typical manifestation and can lead to heart failure. Left ventricular ejection fraction measurement by echocardiography and multigated radionuclide angiography is the most common diagnostic approach to detect cardiac damage, but it identifies a late manifestation of myocardial injury. Early non-invasive imaging techniques are needed for the diagnosis and monitoring of cardiotoxic effects. Although echocardiography and cardiac magnetic resonance are the most commonly used imaging techniques for cardiotoxicity assessment, greater attention is focused on new nuclear cardiologic techniques, which can identify high-risk patients in the early stage and visualize the pathophysiologic process at the tissue level before clinical manifestation. The aim of this review is to summarize the role of nuclear imaging techniques in the non-invasive detection of myocardial damage related to antineoplastic therapy at the reversible stage, focusing on the current role and future perspectives of nuclear imaging techniques and molecular radiotracers in detection and monitoring of cardiotoxicity.

Cardiac complications of chemotherapy: role of imaging

OPINION STATEMENT

New advances in cancer diagnosis and treatment have increased survival rates in patients with cancer. In parallel with this increase in the number of cancer survivors is an increasing prevalence of cardiac complications from cancer treatment. Chemotherapy-induced cardiac dysfunction is a major contributor to adverse morbidity and mortality rates in cancer patients. Evidence suggests that both clinical symptoms and the traditional left ventricular ejection fraction (LVEF) may lack sensitivity as measures of cardiotoxicity. The early identification of subclinical LV dysfunction is becoming increasingly important, as this may allow cancer patients and their physicians to make informed decisions about therapeutic options. The features of echocardiography make it a useful tool in the diagnosis and monitoring of cardiotoxicity. This review will examine the role of cardiac imaging in detecting cardiotoxicity, focusing primarily on the conventional and more recent echocardiographic approaches for assessing subclinical cardiotoxicity.

Biomarkers for the early detection of anthracycline-induced cardiotoxicity: current status

BACKGROUND

Cardiotoxicity is a well-known and potentially serious complication of anticancer therapy. Anthracycline-based chemotherapy represents the greatest risk. Early detection of cardiotoxicity is crucial for applying preventive and supportive therapeutic strategies.

METHODS AND RESULTS

Various methods have been recommended for monitoring of cardiotoxicity. In our conditions, echocardiography and electrocardiography are routinely used. However, this approach shows low sensitivity for the early prediction of cardiomyopathy when the possibilities of appropriate management could still improve the patient's outcome. Recently, biomarkers of cardiac injury have been investigated in the assessment of chemotherapy-induced cardiotoxicity. Cardiospecific biomarkers, such as cardiac troponins, show high diagnostic efficacy in the early subclinical phase of the disease before the clinical onset of cardiomyopathy. Increase in their concentrations correlates with disease severity. As for natriuretic peptides, some studies, including ours, have shown promising results. Definitive evidence of their diagnostic and prognostic role in this context is still lacking and natriuretic peptides have not been routinely used for monitoring of cardiotoxicity in clinical practice. Other perspective biomarkers of cardiotoxicity in oncology are under study, especially heart-type fatty acid-binding protein (H-FABP) and glycogen phosphorylase BB (GPBB). Our studies using GPBB have provided encouraging results. However, the available data are limited and their practical use in this context cannot be recommended until their clinical efficacy is clearly defined.

CONCLUSIONS

This review covers the current status of biomarkers for the early detection of anthracycline-induced cardiotoxicity. The authors present in brief, their own experience with multiple biomarkers in the detection of cardiotoxicity.

Using cardiac biomarkers and treating cardiotoxicity in cancer

Cardiotoxicity is a frequent and serious adverse effect of both conventional and novel anticancer treatments, affecting patient survival and quality of life. The current standard for cardiac monitoring during cancer therapy, mainly based on left ventricular ejection fraction assessment, detects myocardial damage only when a functional impairment has already occurred, not allowing for early preventive strategies. Measurement of cardiospecific biomarkers has proven to have higher prognostic value than imaging modalities. In particular, cardiac troponin elevation during chemotherapy allows the identification of patients who are more prone to develop myocardial dysfunction and cardiac events during follow-up. In these patients, the use of an angiotensin-converting enzyme inhibitor such as enalapril has shown to be effective in improving clinical outcome, giving the chance for a cardioprotective strategy in a selected population. Once left ventricular dysfunction occurs, heart failure therapies currently used for other forms of left ventricular dysfunction, particularly angiotensin-converting enzyme inhibitors and β-blockers, seem to be effective. However, their use in cancer patients is still undervalued.

Traditional and novel methods to assess and prevent chemotherapy-related cardiac dysfunction noninvasively

The field of cardio-oncology is challenged to address an ever greater spectrum of cardiotoxicity associated with combination chemotherapy, greater dose intensity, extremes of age, and enhanced patient survival which exposes more protracted risk of developing congestive heart failure (CHF). Recent reports of chemotherapy-induced hypertension as a common adverse effect of angiogenesis inhibitors and immunosuppressants clarify the need for routine blood pressure (BP) monitoring and guideline-based management of hypertension as an integral strategy to preserve LV function. Serial monitoring of radionuclide left ventricular ejection fraction (LVEF) in adults and echocardiography in children continues to provide outcome based, cost-effective prevention of CHF in high risk patients receiving chemotherapy. To optimize treatment and monitoring strategies to eliminate late-onset LV dysfunction and CHF, traditional and novel candidate methods for assessment of chemotherapy-induced LV dysfunction are reviewed. These include serial assessment of LV volume indices by gated SPECT ERNA and gated SPECT MPI, 3D echocardiography and contrast 2D echocardiography; longitudinal strain imaging, diastolic functional parameters, (123)I-MIBG, (111)In-Antimyosin antibody imaging, and (99m)Tc-Annexin V apoptosis imaging, biomarkers including troponins and BNP; genetic markers, and both functional and tissue characterization techniques with T1 weighted and T2 weighted images with cardiac magnetic resonance imaging (CMR). In our quest to optimize strategies for long-term cancer survival and prevention of CHF for patients receiving chemotherapy, rigorous modality and guideline-specific clinical outcome trials are required. A new multi-modality monitoring approach is proposed, which integrates evidence-based strengths of CMR, echocardiography, ERNA, biomarkers, and BP management for surveillance and validation of cardiotoxicity and prevention of clinical heart failure in patients receiving a broad spectrum of cancer therapies.

The relationship between changes in functional cardiac parameters following anthracycline therapy and carbonyl reductase 3 and glutathione S transferase Pi polymorphisms

The aim of this prospective clinical study is to evaluate the relationship between changes in functional cardiac parameters following anthracycline therapy and carbonyl reductase 3 (CBR3p.V244M) and glutathione S transferase Pi (GSTP1p.I105V) polymorphisms. Seventy patients with normal cardiac function and no history of cardiac disease scheduled to undergo anthracycline chemotherapy were included in the study. The patients' cardiac function was evaluated by gated blood pool scintigraphy and echocardiography before and after chemotherapy, as well as 1 year following therapy. Gene polymorphisms were genotyped in 70 patients using TaqMan probes, validated by DNA sequencing. A deteriorating trend was observed in both systolic and diastolic parameters from GG to AA in CBR3p.V244M polymorphism. Patients with G-allele carriers of GSTP1p.I105V polymorphism were common (60%), with significantly decreased PFR compared to patiens with AA genotype. Variants of CBR3 and GSTP1 enzymes may be associated with changes in short-term functional cardiac parameters.

Prediction of anthracycline cardiotoxicity after chemotherapy by biomarkers kinetic analysis

Anthracyclines are active drugs against breast cancer, but can exert cardiotoxic effects. We analyzed the association between the kinetics of various biomarkers during chemotherapy, and the risk of subsequent cardiac toxicity. 50 patients (49 women) with early breast cancer surgically treated and eligible to anthracycline-based adjuvant chemotherapy were analyzed. The left ventricular ejection fraction (LVEF) together with the plasma concentration of several blood markers was measured at the beginning of anthracycline chemotherapy (t (0)), 5 months (t (1)), 16 months (t (2)), 28 months (t (3)), and 40 months later (t (4)). A single measured LVEF value less than 50% or a clinically overt congestive heart failure (CHF) was considered cardiotoxic effects. We tested whether the kinetics of LVEF and blood biomarkers measured during chemotherapy was predictive of subsequent cardiotoxicity and overall cardiac fitness. The left ventricular ejection fraction measured at the end of treatment as well as the rate of change of hemoglobin concentration during anthracycline-based chemotherapy predicted cardiotoxicity in a 3-year follow-up period. When LVEF at the end of chemotherapy was lower than 53% or hemoglobin blood concentration declined more than 0.33 g/dL/month during chemotherapy, the odds ratio of subsequent cardiotoxicity was 37.3 and 18, respectively. The specificity of these two tests was 93.3% and 80%, whereas the sensitivity was 90.9 and 81.2%, respectively. Testing the rate of change of hemoglobin concentration during anthracycline-based chemotherapy, as well as the left ventricular ejection fraction at the end of treatment, seems a powerful method to assess the effects of anthracyclines on cardiac fitness and identify patients at high risk of CHF. Further validation of these tests on a large cohort of patients and cost-benefit analysis should be encouraged.

Cardiac imaging approaches to evaluate drug-induced myocardial dysfunction

The ability to make informed benefit-risk assessments for potentially cardiotoxic new compounds is of considerable interest and importance at the public health, drug development, and individual patient levels. Cardiac imaging approaches in the evaluation of drug-induced myocardial dysfunction will likely play an increasing role. However, the optimal choice of myocardial imaging modality and the recommended frequency of monitoring are undefined. These decisions are complicated by the array of imaging techniques, which have varying sensitivities, specificities, availabilities, local expertise, safety, and costs, and by the variable time-course of tissue damage, functional myocardial depression, or recovery of function. This White Paper summarizes scientific discussions of members of the Cardiac Safety Research Consortium on the main factors to consider when selecting nonclinical and clinical cardiac function imaging techniques in drug development. We focus on 3 commonly used imaging modalities in the evaluation of cardiac function: echocardiography, magnetic resonance imaging, and radionuclide (nuclear) imaging and highlight areas for future research.

Cancer drugs and the heart: importance and management

Progress in the detection and treatment of cancer has led to an impressive reduction in both mortality and morbidity. Due to their mechanism of action, however, conventional chemotherapeutics and some of the newer anti-cancer signaling inhibitors carry a substantial risk of cardiovascular side effects that include cardiac dysfunction and heart failure, arterial hypertension, vasospastic and thromboembolic ischaemia, dysrhythmia, and QT prolongation. While some of these side effects are irreversible and cause progressive cardiovascular disease, others induce only temporary dysfunction with no apparent long-term sequelae for the patient. The challenge for the cardiovascular specialist is to balance the need for life-saving cancer treatment with the assessment of risk from cancer drug-associated cardiovascular side effects to prevent long-term damage. This review discusses concepts for timely diagnosis, intervention, and surveillance of cancer patients undergoing treatment, and provides approaches to clinical uncertainties.

Cardiotoxicity in childhood cancer survivors: strategies for prevention and management

Advances in cancer treatment have greatly improved survival rates of children with cancer. However, these same chemotherapeutic or radiologic treatments may result in long-term health consequences. Anthracyclines, chemotherapeutic drugs commonly used to treat children with cancer, are known to be cardiotoxic, but the mechanism by which they induce cardiac damage is still not fully understood. A higher cumulative anthracycline dose and a younger age of diagnosis are only a few of the many risk factors that identify the children at increased risk of developing cardiotoxicity. While cardiotoxicity can develop at anytime, starting from treatment initiation and well into adulthood, identifying the best cardioprotective measures to minimize the long-term damage caused by anthracyclines in children is imperative. Dexrazoxane is the only known agent to date, that is associated with less cardiac dysfunction, without reducing the oncologic efficacy of the anthracycline doxorubicin in children. Given the serious long-term health consequences of cancer treatments on survivors of childhood cancers, it is essential to investigate new approaches to improving the safety of cancer treatments.

Non-invasive imaging and monitoring cardiotoxicity of cancer therapeutic drugs

Cardiotoxicity due to administration of cancer therapeutic agents such as anthracyclines and herceptin are well described. Established guidelines to screen for chemotherapy-related cardiotoxicity (CRC) are primarily based on serial assessment of left ventricular (LV) ejection fraction (EF). However, other parameters such as LV volume, diastolic function, and strain may also be useful in screening for cardiotoxicity. More recent advances in molecular imaging of apoptosis and tissue characterization by cardiac MRI are techniques which might allow early detection of patients at high risk for developing cardiotoxicity prior to a drop in EF. This comprehensive multi-modality review will discuss both the current established imaging techniques as well as the emerging technologies which may revolutionize the future of screening and evaluation for CRC.

Value of echocardiography and electrocardiography as screening tools prior to Doxorubicin administration

The dose-limiting toxicity of doxorubicin is cardiotoxicosis. The authors of this report hypothesized that by using their institution's adopted guidelines (that involve prescreening echocardiography and electrocardiography), they would detect pre-existing cardiac abnormalities that preclude doxorubicin administration in <10% of dogs. Of 101 dogs, only 6 were excluded from doxorubicin administration based on electrocardiogram abnormalities, with a majority of those arrhythmias classified as ventricular premature contractions. One patient was excluded based on echocardiogram alone due to hypertrophic cardiomyopathy. The incidence of cardiotoxicity in treated dogs was 8% (8/101). Additional pretreatment and ongoing studies are indicated to identify risk factors for cardiotoxicity.

Long-term cardiac and pulmonary complications of cancer therapy

Cardiac complications resulting from chemotherapy and radiation pose a significant risk for morbidity and mortality to the cancer survivor. Cardiac side effects may progress over time and are a concern for patients treated during childhood. Long-term pulmonary complications are relatively infrequent, and acute respiratory effects of drugs (mostly bleomycin) or radiation normally resolve early after therapy. Although most cardiovascular risk statistics and clinical experience are derived from patients treated before 1985, the modern radiation approach that limits the exposure of the heart and reduces the total dose seems to attenuate the previously observed cardiovascular risk. Potential preventive measures for high-risk patients are of increasing interest but remain experimental.

Scintigraphic techniques for early detection of cancer treatment-induced cardiotoxicity

New antitumor agents have resulted in significant survival benefits for cancer patients. However, several agents may have serious cardiovascular side effects. Left ventricular ejection fraction measurement by (99m)Tc multigated radionuclide angiography is regarded as the gold standard to measure cardiotoxicity in adult patients. It identifies left ventricular dysfunction with high reproducibility and low interobserver variability. A decrease in left ventricular ejection fraction, however, is a relatively late manifestation of myocardial damage. Nuclear cardiologic techniques that visualize pathophysiologic processes at the tissue level could detect myocardial injury at an earlier stage. These techniques may give the opportunity for timely intervention to prevent further damage and could provide insights into the mechanisms and pathophysiology of cardiotoxicity caused by anticancer agents. This review provides an overview of past, current, and promising newly developed radiopharmaceuticals and describes the role and recent advances of scintigraphic techniques to measure cardiotoxicity. Both first-order functional imaging techniques (visualizing mechanical [pump] function), such as (99m)Tc multigated radionuclide angiography and (99m)Tc gated blood-pool SPECT, and third-order functional imaging techniques (visualizing pathophysiologic and neurophysiologic processes at the tissue level) are discussed. Third-order functional imaging techniques comprise (123)I-metaiodobenzylguanidine scintigraphy, which images the efferent sympathetic nervous innervations; sympathetic neuronal PET, with its wide range of tracers; (111)In-antimyosin, which is a specific marker for myocardial cell injury and necrosis; (99m)Tc-annexin V scintigraphy, which visualizes apoptosis and cell death; fatty-acid-use scintigraphy, which visualizes the storage of free fatty acids in the lipid pool of the cytosol (which can be impaired by cardiotoxic agents); and (111)In-trastuzumab imaging, to study trastuzumab targeting to the myocardium. To define the prognostic importance and clinical value of each of these functional imaging techniques, prospective clinical trials are warranted.

Cardiotoxicity after anthracycline chemotherapy in breast carcinoma: effects on left ventricular ejection fraction, troponin I and brain natriuretic peptide

Anthracyclines are among the most active drugs in breast cancer patients. We planned to evaluate the early and 2-year modification of left ventricular ejection fraction (LVEF) and the effects of chemotherapy on troponin I and neurohormonal assessment.

METHODS

Patients with early breast cancer surgically treated and eligible to adjuvant chemotherapy were enrolled. All patients underwent clinical assessment, radionuclide ventriculography, troponin I and brain natriuretic peptide (BNP) measurements at baseline and one-month (T1), one year (T2) and 2-year (T3) after chemotherapy. Reductions of LVEF ≥ 10% or an overt heart failure were considered cardiovascular events.

RESULTS

53 patients, 52 females and 1 male, age 55.3 years were included and followed at T3. A significant reduction of LVEF was observed (from 62 ± 5.5% to 59.3 ± 8.6%, p=0.04) at T3; BNP increased (from 33.4 ± 41.5 pg/ml to 62.7 ± 94.7 pg/ml, p=0.005) at T1. Troponin I augmented at T1 (from 0.006 ± 0.01 ng/ml to 0.05 ± 0.04 ng/ml, p=0.0001) but normalized at T2 (0.005 ± 0.08 ng/ml; p=0.9). Only baseline BNP was nearly to be significantly correlated with T3 LVEF (p=0.07 HR 0.96-1) at multivariate analysis. In 13/53 patients (32.1%) LVEF showed ≥ 10% reduction at T3 (group A); in 40/53 patients (67.9%) LVEF was unchanged (group B). Patients in group A demonstrated higher baseline plasma BNP (p=0.02) and lower haemoglobin concentration (p=0.007) compared to patients in group B.

CONCLUSIONS

LVEF and BNP modified early after anthracycline chemotherapy and LVEF did not recover at T3. In patients who developed left ventricular systolic dysfunction, a subclinical activation of neurohormonal profile was observed.

Cardiovascular toxicity caused by cancer treatment: strategies for early detection

Cardiovascular toxicity is one of the most devastating complications of cancer treatment and can arise during or shortly after treatment, or even several years later. Identification of the left ventricular ejection fraction (LVEF) is the most common method to screen for toxic effects on the heart; however, this approach underestimates cardiac damage and additional strategies for the monitoring of treatment-induced cardiotoxicity are being explored. Guidelines for monitoring have been formulated for several cancer treatments; however, appropriate underlying evidence is still largely absent. In this Review, we summarise conventional and contemporary methods for early detection of cardiotoxicity and designate a level of evidence for the basis of each method.

Expert opinion on the use of anthracyclines in patients with advanced breast cancer at cardiac risk

Anthracyclines are considered to be among the most active agents for the treatment of breast cancer. However, their use is limited by cumulative, dose-related cardiotoxicity. Such cardiotoxicity results in a permanent loss of cardiac myocytes and a progressive reduction in cardiac function following each subsequent dose of anthracycline. Initially, damage to the heart is subclinical; however, increasingly impaired cardiac function can result in cardiovascular symptoms, with serious cardiac injury resulting in chronic heart failure. Since the early detection and treatment of cardiotoxicity can reduce its clinical effects, it is important that oncologists are aware of these adverse effects and manage them appropriately. This review examines the risk factors for anthracycline-associated cardiotoxicity and offers recommendations on strategies to reduce the cardiotoxicity of anthracyclines in the management of patients with advanced breast cancer.

EANM/ESC guidelines for radionuclide imaging of cardiac function

Radionuclide imaging of cardiac function represents a number of well-validated techniques for accurate determination of right (RV) and left ventricular (LV) ejection fraction (EF) and LV volumes. These first European guidelines give recommendations for how and when to use first-pass and equilibrium radionuclide ventriculography, gated myocardial perfusion scintigraphy, gated PET, and studies with non-imaging devices for the evaluation of cardiac function. The items covered are presented in 11 sections: clinical indications, radiopharmaceuticals and dosimetry, study acquisition, RV EF, LV EF, LV volumes, LV regional function, LV diastolic function, reports and image display and reference values from the literature of RVEF, LVEF and LV volumes. If specific recommendations given cannot be based on evidence from original, scientific studies, referral is given to "prevailing or general consensus". The guidelines are designed to assist in the practice of referral to, performance, interpretation and reporting of nuclear cardiology studies for the evaluation of cardiac performance.

Cardiac toxicity in breast cancer survivors: review of potential cardiac problems

As breast cancer survival is increased by the diagnosis of earlier-stage disease and treatments improve, the side effects of cancer treatments, such as cardiotoxicity, remain clinically important. Although physicians have known for 30 years that anthracyclines cause acute and chronic cardiotoxicity, the cardiotoxic effects of radiation therapy, hormonal therapy (including tamoxifen and the aromatase inhibitors), and chemotherapy with taxanes and trastuzumab treatment have emerged more recently. This review examines the cardiac toxicity of adjuvant therapy, monitoring for early changes and existing guidelines for monitoring cardiac function in patients with breast cancer.

Potentiation of Doxorubicin cardiotoxicity by iron loading in a rodent model

OBJECTIVES

The role of iron toward doxorubicin (DOX) cardiotoxicity was studied using a rodent model of dietary carbonyl iron loading.

BACKGROUND

Doxorubicin, a commonly used anticancer drug, is known to cause serious and potentially life-threatening cardiotoxicity. Doxorubicin cardiotoxicity is thought to be mediated through free-radical injury.

METHODS

Male Sprague Dawley rats fed iron-rich chow (n = 8) and regular chow (n = 8) were treated with DOX or saline (4 animals in each arm). Cardiotoxicity was assessed using mortality, weight changes, Tc-99m annexin-V imaging, histopathology, and immunohistochemistry.

RESULTS

Animals fed iron-rich chow showed significantly higher DOX cardiotoxicity as evidenced by greater weight loss (107 +/- 14 g vs. 55 +/- 10 g weight loss, p < 0.05), higher annexin uptake (0.14 +/- 0.01% vs. 0.08 +/- 0.01% injected dose/g of myocardium, p < 0.05), more severe myocyte injury on electron microscopy, and significantly higher cleaved caspase-3 staining compared with regular chow fed rats given DOX. Feeding iron-rich chow alone did not result in any cardiotoxicity.

CONCLUSIONS

Dietary iron loading resulted in a substantially increased DOX cardiotoxicity in rats. Body iron stores as well as its bioavailability in tissue may be important independent predictors of susceptibility to DOX cardiotoxicity in man. Further clinical studies are warranted.

Monitoring chemotherapy-induced cardiotoxicity: role of cardiac nuclear imaging

Cardiotoxicity may result from a range of chemotherapeutic agents. The prevalence of cardiotoxicity from certain cytotoxic agents is reported to be significantly high. In addition to serious side effects and increased long-lasting morbidity and mortality, dose limitation and suboptimal usage is an important adverse effect. Nuclear cardiac imaging has played a quintessential and important role in identifying patients at risk and in the prevention and reduction of cardiac injury resulting from cytotoxic agents. Despite exploring a number of other diagnostic imaging or biochemical tools for identification of cardiac injury, nuclear cardiac imaging in the form of radionuclide angiocardiography continues to be the most suitable and cost-effective tool for reducing the prevalence of cases of cardiac dysfunction resulting from chemotherapy. This article reviews the prevalence, mechanisms, and prevention strategies for cardiotoxicity associated with some of the commonly known cytotoxic agents and the role of nuclear cardiac imaging in its monitoring and prevention, along with recent advances in this area.

Tei index in adult patients submitted to adriamycin chemotherapy: failure to predict early systolic dysfunction

AIMS

This study prospectively assessed whether Tei index is predictive of early systolic dysfunction in adults undergoing adriamycin treatment.

METHODS AND RESULTS

Left ventricular ejection fraction (LVEF) was obtained by radionuclide ventriculography at baseline and after treatment. Tei index was evaluated by echocardiography at baseline, at an intermediary cycle and at the end of chemotherapy. Fifty-five predominantly female patients (91%) with breast cancer (80%) and without known cardiac disease were evaluated. After treatment (adriamycin dose of 304 +/- 47 mg/m(2)), systolic dysfunction (final LVEF < 50%) occurred in eight patients (14%). Baseline, intermediate or variation of Tei index were not accurate to predict early systolic dysfunction ("c" statistics < or = 0.60). Baseline Tei index > 0.39, for example, had a sensitivity of 75%, specificity of 55%, positive predictive value of 22% and negative predictive value of 93%.

CONCLUSION

Tei index does not appear to be a useful tool for detection of early adriamycin cardiotoxicity in adults.

Anticancer agents and cardiotoxicity

Although rare, cardiotoxicity is a significant complication of cancer treatment. The incidence and severity of cardiotoxicity are dependent on the type of drugs used, dose and schedule employed, and age of patients, as well as the presence of coexisting cardiac diseases and previous mediastinal irradiation. Anthracyclines are among one of the most active agents in oncology, but their use is often hampered by their cumulative dose-limiting cardiotoxicity. Combination therapy with new drugs in the last decade, such as taxanes and trastuzumab, in the treatment of metastatic breast cancer has yielded impressive results but also unexpected cardiotoxicity. Existing methods of minimizing cardiotoxicity include the use of protective agents such as dexrazoxane, different preparations of anthracyclines such as liposomal formulations, and alternative scheduling techniques. Assessment of left ventricular ejection fraction (LVEF) with two-dimensional (2D)-echocardiography or radionuclide ventriculography (RNVG) remains the most pragmatic means of monitoring for cardiotoxicity. The increasing number of long-term survivors of pediatric cancers, as well as the use of trastuzumab, taxanes, and anthracyclines in adjuvant treatment of breast cancer, means that more than ever, cardiotoxicity will remain an important issue for clinicians.

The prevention and management of cardiovascular complications of chemotherapy in patients with cancer

Cardiac toxicity of chemotherapeutic agents is a rapidly evolving area of increasing significance because of the increasing pool of long-term cancer survivors. The spectrum of cardiotoxicity with chemotherapeutic agents includes hypertension, QTc prolongation, acute cardiomyopathy, and bradyarrhythmias. The most common issue to arise has been cardiomyopathy with anthracyclines. Preventative strategies that have met with some success have included the use of less cardiotoxic analogs such as epirubicin and liposomal anthracycline preparations. The cardioprotectant agent dexrazoxane reduces cardiomyopathy but there are significant toxicity issues. Therefore, the main strategy for preventing cardiotoxicity remains careful monitoring with radionuclide angiography or echocardiography. The role of investigational markers of myocardial injury, such as troponin T or brain natriuretic peptide, remains of great interest. Management is according to conventional management of congestive heart failure. Trastuzumab is an antibody therapy directed against the human epidermal growth factor receptor-2 (HER2) receptor, which increases survival in patients with metastatic breast cancer and is under evaluation in the adjuvant setting. It also causes a decrease in left ventricular ejection fraction (LVEF) in a minority of patients. Incidence is increased if trastuzumab is given in conjunction with paclitaxel or anthracyclines. It differs from anthracycline cardiotoxicity in that it is not cumulative dose-dependent and often improves after withdrawal of treatment. Re-treatment with trastuzumab is often possible. Novel agents under development offer a different spectrum of toxicity to existing anticancer drugs and it appears likely that cardiovascular toxicity will be an important issue for many of these drugs, particularly those that target the tumor vasculature.

Monitoring Cardiac Function in Patients Receiving Doxorubicin

Despite its well-known cardiotoxicity, doxorubicin continues to be an effective and widely used antineoplastic agent. Many efforts have focused on understanding the mechanism of doxorubicin-induced cardiotoxicity and on preventing it completely. Currently protective agents, eg, liposomal doxorubicin formulation, which results in less myocardial uptake, and the use of dexrazoxane, an intracellular iron chelator reducing the formation of radical complexes, have shown evidence of reducing incidences of cardiotoxicity at high dose of doxorubicin. However, they have not been able to completely eliminate cardiotoxicity. Therefore, it is crucial that careful monitoring to identify those patients who are at risk of developing unpredictable and sometimes-irreversible cardiac dysfunction is conducted while allowing other patients who respond to doxorubicin-containing therapy to receive their maximal therapeutic dose. Serial measurement of left ventricular ejection fraction by radionuclide angiocardiography remains a useful and widely adopted modality in monitoring patients that are receiving doxorubicin. Efforts are continuing on finding a more sensitive and reliable predictor of eventual clinical cardiac dysfunction.

Concurrent therapies that protect against doxorubicin-induced cardiomyopathy

Doxorubicin is a chemotherapeutic agent successfully used in the treatment of a wide range of cancers. However, with cumulative doses, doxorubicin also is known to have cardiotoxic effects, including cardiomyopathy and heart failure. Research is targeted at maximizing the antitumor effects of doxorubicin while attenuating the potential cardiotoxicity. Concurrent therapies under study are combinations of doxorubicin with drugs such as probucol, carvedilol (Coreg, GlaxoSmithKline, Research Triangle Park, NC), dexrazoxane (Zinecard, Pfizer, New York, NY), and antioxidant nutrients. As patient advocates, nurses must be aware of current research, treatment options, and evidence-based patient resources and be diligent in assessing and educating patients before, during, and after treatment with doxorubicin.