Cardiac diastolic function in pediatric patients receiving doxorubicin

Early myocardial changes induced by doxorubicin in the nonfailing dilated ventricle

Several studies have demonstrated that administration of doxorubicin (DOXO) results in cardiotoxicity, which eventually progresses to dilated cardiomyopathy. The present work aimed to evaluate the early myocardial changes of DOXO-induced cardiotoxicity. Male New Zealand White rabbits were injected intravenously with DOXO twice weekly for 8 wk [DOXO-induced heart failure (DOXO-HF)] or with an equivolumetric dose of saline (control). Echocardiographic evaluation was performed, and myocardial samples were collected to evaluate myocardial cellular and molecular modifications. The DOXO-HF group presented cardiac hypertrophy and higher left ventricular cavity diameters, showing a dilated phenotype but preserved ejection fraction. Concerning cardiomyocyte function, the DOXO-HF group presented a trend toward increased active tension without significant differences in passive tension. The myocardial GSSG-to-GSH ratio and interstitial fibrosis were increased and Bax-to- Bcl-2 ratio presented a trend toward an increase, suggesting the activation of apoptosis signaling pathways. The macromolecule titin shifted toward the more compliant isoform (N2BA), whereas the stiffer one (N2B) was shown to be hypophosphorylated. Differential protein analysis from the aggregate-enriched fraction through gel liquid chromatography-tandem mass spectrometry revealed an increase in the histidine-rich glycoprotein fragment in DOXO-HF animals. This work describes novel and early myocardial effects of DOXO-induced cardiotoxicity. Thus, tracking these changes appears to be of extreme relevance for the early detection of cardiac damage (as soon as ventricular dilation becomes evident) before irreversible cardiac function deterioration occurs (reduced ejection fraction). Moreover, it allows for the adjustment of the therapeutic approach and thus the prevention of cardiomyopathy progression.

NEW & NOTEWORTHY Identification of early myocardial effects of doxorubicin in the heart is essential to hinder the development of cardiac complications and adjust the therapeutic approach. This study describes doxorubicin-induced cellular and molecular modifications before the onset of dilated cardiomyopathy. Myocardial samples from doxorubicin-treated rabbits showed a tendency for higher cardiomyocyte active tension, titin isoform shift from N2B to N2BA, hypophosphorylation of N2B, increased apoptotic genes, left ventricular interstitial fibrosis, and increased aggregation of histidine-rich glycoprotein.

Anthracycline Chemotherapy and Cardiotoxicity

Anthracycline chemotherapy maintains a prominent role in treating many forms of cancer. Cardiotoxic side effects limit their dosing and improved cancer outcomes expose the cancer survivor to increased cardiovascular morbidity and mortality. The basic mechanisms of cardiotoxicity may involve direct pathways for reactive oxygen species generation and topoisomerase 2 as well as other indirect pathways. Cardioprotective treatments are few and those that have been examined include renin angiotensin system blockade, beta blockers, or the iron chelator dexrazoxane. New treatments exploiting the ErbB or other novel pro-survival pathways, such as conditioning, are on the cardioprotection horizon. Even in the forthcoming era of targeted cancer therapies, the substantial proportion of today's anthracycline-treated cancer patients may become tomorrow's cardiac patient.

Biomarkers for monitoring chemotherapy-induced cardiotoxicity

Cardiotoxicity, including acute and late-onset cardiotoxicity, is a well-known adverse effect of many types of antitumor agents. Early identification of patients with cardiotoxicity is important to ensure prompt treatment and minimize toxic effects. The etiology of chemotherapy-induced cardiotoxicity is multifactorial. Traditional methods for assessment of chemotherapy-induced cardiotoxicity typically involve serial measurements of cardiac function via multi-modality imaging techniques. Typically, however, significant left ventricular dysfunction has already occurred when cardiotoxicity is detected by imaging techniques. Biomarkers, most importantly cardiac natriuretic peptides and troponins, are promising markers for identifying patients potentially at risk for clinical heart failure symptoms. This review summarizes the recent progress in clinical utilization of biomarkers for early diagnosis of acute cardiotoxicity and for prediction of late-onset cardiotoxicity. We also discuss the conflicting results of different studies and the association of results with study design.

Cardiotoxicity in anthracycline therapy: Prevention strategies

The increasing use of anthracyclines, together with the longer survival of cancer patients, means the toxic effects of these drugs need to be monitored. In order to detect, prevent or mitigate anthracycline-induced cardiomyopathy, it is essential that all patients undergo a rigorous initial cardiovascular assessment, followed by close monitoring. Several clinical trials have shown the cardioprotective effect of non-pharmacological measures such as exercise, healthy lifestyles, control of risk factors and treatment of comorbidities; a cardioprotective effect has also been observed with pharmacological measures such as beta-blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor antagonists, statins, dexrazoxane and liposomal formulations. However, there are currently no guidelines for managing prevention in these patients. In this review the authors discuss the state of the art of the assessment, monitoring, and, above all, the prevention of anthracycline-induced cardiotoxicity.

An integrated characterization of serological, pathological, and functional events in doxorubicin-induced cardiotoxicity

Many efficacious cancer treatments cause significant cardiac morbidity, yet biomarkers or functional indices of early damage, which would allow monitoring and intervention, are lacking. In this study, we have utilized a rat model of progressive doxorubicin (DOX)-induced cardiomyopathy, applying multiple approaches, including cardiac magnetic resonance imaging (MRI), to provide the most comprehensive characterization to date of the timecourse of serological, pathological, and functional events underlying this toxicity. Hannover Wistar rats were dosed with 1.25 mg/kg DOX weekly for 8 weeks followed by a 4 week off-dosing "recovery" period. Electron microscopy of the myocardium revealed subcellular degeneration and marked mitochondrial changes after a single dose. Histopathological analysis revealed progressive cardiomyocyte degeneration, hypertrophy/cytomegaly, and extensive vacuolation after two doses. Extensive replacement fibrosis (quantified by Sirius red staining) developed during the off-dosing period. Functional indices assessed by cardiac MRI (including left ventricular ejection fraction (LVEF), cardiac output, and E/A ratio) declined progressively, reaching statistical significance after two doses and culminating in "clinical" LV dysfunction by 12 weeks. Significant increases in peak myocardial contrast enhancement and serological cardiac troponin I (cTnI) emerged after eight doses, importantly preceding the LVEF decline to <50%. Troponin I levels positively correlated with delayed and peak gadolinium contrast enhancement, histopathological grading, and diastolic dysfunction. In summary, subcellular cardiomyocyte degeneration was the earliest marker, followed by progressive functional decline and histopathological manifestations. Myocardial contrast enhancement and elevations in cTnI occurred later. However, all indices predated "clinical" LV dysfunction and thus warrant further evaluation as predictive biomarkers.

Protective effect of carvedilol on adriamycin-induced left ventricular dysfunction in children with acute lymphoblastic leukemia

BACKGROUND

Adriamycin (ADR) is a potent chemotherapeutic agent widely used in the treatment of childhood acute lymphoblastic leukemia (ALL); its clinical use is limited owing to its marked cardiotoxicity. The present study investigated the possible protective role of carvedilol on ADR-induced left ventricular dysfunction in children with ALL.

METHODS AND RESULTS

Fifty children with newly diagnosed ALL were included in this study. They were divided into 2 equal groups: 1) ADR; and 2) ADR + carvedilol. Patients were evaluated with conventional 2-dimensional echocardiographic examination (2D), pulsed tissue Doppler (PTD), and 2-dimensional longitudinal strain echocardiography (2DS) before and after therapy. Plasma lactic dehydrogenase (LDH), creatine phosphokinase (CPK), and troponin I levels were also determined before and after therapy. ADR treatment reduced left ventricular systolic dysfunction as assessed by a significant decrease in fractional shortening (FS) (2D) and global peak-systolic strain (GPSS; 2DS). In addition, ADR treatment significantly increased plasma troponin I and LDH. Pretreatment of ADR-treated patients with carvedilol resulted in a significant increase in FS (2D) and GPSS (2DS). Furthermore, carvedilol pretreatment inhibited ADR-induced increase in plasma troponin I and LDH.

CONCLUSIONS

These results suggested a protective role of carvedilol against ADR-induced cardiotoxicity.

Chemotherapy-induced cardiotoxicity

Anthracycline-based chemotherapeutics have long been recognized as effective agents for treating a wide range of malignancies. However, their use is not without significant adverse cardiotoxic side effects. Strategies for prevention involve limiting free-radical production and subsequent cardiac myocyte damage. Dexrazoxane remains the most widely studied cardioprotective medication. Alternative agents may reduce cardiotoxicity but may still cause significant cardiovascular problems. The role of β-blockers and angiotensin-converting enzyme inhibitors in the treatment of heart failure is well proven. The role of these medications in the prevention and treatment of chemotherapy-induced cardiotoxicity is not well established.

Long-term cardiac follow-up of children treated with anthracycline doses of 300 mg/m2 or less for acute lymphoblastic leukemia

BACKGROUND

The cardiotoxic effect of anthracyclines has been well described for moderate to high cumulative doses (>350 mg/m(2)). However, the question of whether sub-clinical signs of cardiomyopathy may develop and progress over time in children receiving doses of <350 mg/m(2) is controversial. The aim of the present study was to examine cardiac function with serial echocardiography from diagnosis to last follow-up, relapse, or death, and to investigate whether suspected risk factors (e.g., age at diagnosis, gender, cumulative dose, and length of follow-up) had a significant influence on cardiac function.

PROCEDURE

An unselected cohort of 80 patients treated with multi-drug chemotherapy including anthracycline doses of 300 mg/m(2) or less for childhood acute lymphoblastic leukemia was followed with serial echocardiograms. The deviations of each echocardiogram from normal values for the same age and body-surface areas were calculated. The influences of risk factors were analyzed using univariate and multivariate regression. Lowess curves of time dependence were calculated.

RESULTS

All echocardiographic parameters including ejection fraction (EF) deteriorated significantly over time. Male gender was significantly associated with systolic dilatation of the left ventricle and positively associated with left ventricular mass. Reduction of EF was significantly associated with age at diagnosis and male gender.

CONCLUSIONS

Anthracycline doses of <300 mg/m(2) may contribute to a decline in cardiac function over time. Although the deterioration in cardiac parameters was not associated with clinical symptoms, life-long cardiac surveillance for these patients is important to establish the impact of low-dose anthracycline therapy on long-term cardiac health.

Usefulness of myocardial performance index and biochemical markers for early detection of anthracycline-induced cardiotoxicity in adults

BACKGROUND

Anthracycline therapy is limited by cardiotoxicity. Currently no diagnostic parameter is available allowing ubiquitous and reliable detection of preclinical anthracycline cardiomyopathy and prediction of prognosis.

PATIENTS AND METHODS

In 100 consecutive patients receiving anthracycline-based chemotherapy serial measurements of left ventricular systolic and diastolic function, Tei index (a Doppler echocardiographic parameter of global ventricular function), cardiac troponin T (cTnT) and NT-probrain natriuretic peptides (BNP) at baseline and during 1-year follow-up were performed.

RESULTS

Mean ejection fraction (LVEF) significantly decreased immediately after completion of anthracycline therapy (mean dose 226.1 +/- 8.3 mg/m(2)) und further declined during follow-up (65.9 +/- 0.6% Vs. 61.6 +/- 0.7%; P < 0.001), while mean E/A ratio decreased after 6 months (P = 0.05). No patient presented with cardiac symptoms. The Tei index increased after therapy in the majority of patients (78.8%) compared with pre-therapy values indicating myocardial alteration in more patients than previously recognized. cTnT levels did not exceed the upper limit of the normal range in any patient. Seven patients had low-level elevations of cTnT. Only one of these patients developed a concomitant decrease in LVEF. Mean N-terminal-pro-BNP (NT-proBNP) levels did not significantly change after anthracycline administration. However, in 13 patients (15.3%) a marked, transient increase of NT-proBNP was obtained after the first anthracycline cycle without cardiac dysfunction presumably due to altered cardiac loading conditions during chemotherapy.

CONCLUSION

Low to moderate doses of anthracyclines resulted in subclinical myocardial alteration in more patients than so far noticed. Clinical implications of increased Tei index remain to be determined in long-term. Our results do not support that assessment of cTnT or BNP levels may safely replace serial echocardiographic evaluation of systolic and diastolic function for the monitoring of anthracycline cardiotoxicity.

Ventricular systolic reserve in asymptomatic children previously treated with low doses of anthracyclines

Doppler echocardiography has been used for the diagnosis of anthracycline-induced cardiotoxicity. However, few data are available that include asymptomatic children previously treated with a low cumulative dose of this drug and therefore have a low risk of cardiac dysfunction. The aim of this study was to evaluate after-exercise cardiac function in asymptomatic children previously treated with a low cumulative dose of anthracycline and no clinical or laboratory evidence of cardiotoxicity. Doppler echocardiography was performed before and immediately after physical exercise in 29 children aged 5 to 17 years (anthracycline [ADRIA] group). All had finished cancer treatment with anthracycline derivatives for > or =1 year (cumulative dose 100 mg/m(2)). Results were compared with those from age- and gender-matched healthy children (control group; n = 26) using the Mann-Whitney rank test. Exercise-induced cardiac function changes within groups were analyzed using Wilcoxon's signed-rank test. Exercise induced significant increases in left ventricular systolic function indexes in both groups. However, the ADRIA group had significantly lower changes in left ventricular ejection fraction (ADRIA group 0.71 +/- 0.02 vs 0.80 +/- 0.04 and control group 0.71 +/- 0.02 vs 0.89 +/- 0.05, p = 0.0017) and end-systolic stress-volume index (ADRIA group 4.59 +/- 0.69 vs 6.4 +/- 2.0 g.cm(-2)/ml.m(-2) and control group 5.49 +/- 0.98 vs 11.54 +/- 2.86 g.cm(-2)/ml.m(-2); p <0.0001), indicating decreased functional systolic reserve. In conclusion, asymptomatic children previously treated with low cumulative doses of anthracycline had decreased functional systolic reserve evidenced by exercise, suggesting a nonclinically manifested cardiotoxicity.

Cancer therapy and cardiotoxicity: the need of serial Doppler echocardiography

Cancer therapy has shown terrific progress leading to important reduction of morbidity and mortality of several kinds of cancer. The therapeutic management of oncologic patients includes combinations of drugs, radiation therapy and surgery. Many of these therapies produce adverse cardiovascular complications which may negatively affect both the quality of life and the prognosis. For several years the most common noninvasive method of monitoring cardiotoxicity has been represented by radionuclide ventriculography while other tests as effort EKG and stress myocardial perfusion imaging may detect ischemic complications, and 24-hour Holter monitoring unmask suspected arrhythmias. Also biomarkers such as troponine I and T and B-type natriuretic peptide may be useful for early detection of cardiotoxicity. Today, the widely used non-invasive method of monitoring cardiotoxicity of cancer therapy is, however, represented by Doppler-echocardiography which allows to identify the main forms of cardiac complications of cancer therapy: left ventricular (systolic and diastolic) dysfunction, valve heart disease, pericarditis and pericardial effusion, carotid artery lesions. Advanced ultrasound tools, as Integrated Backscatter and Tissue Doppler, but also simple ultrasound detection of "lung comet" on the anterior and lateral chest can be helpful for early, subclinical diagnosis of cardiac involvement. Serial Doppler echocardiographic evaluation has to be encouraged in the oncologic patients, before, during and even late after therapy completion. This is crucial when using anthracyclines, which have early but, most importantly, late, cumulative cardiac toxicity. The echocardiographic monitoring appears even indispensable after radiation therapy, whose detrimental effects may appear several years after the end of irradiation.

Anthracycline cardiotoxicity

The use of anthracyclines is limited by dose-dependent cardiotoxicity. Three forms of anthracycline cardiotoxicity are described; an immediate pericarditis-myocarditis syndrome, an early onset chronic progressive CHF developing during or shortly after therapy and late-onset cardiotoxicity presenting years following treatment. A number of risk factors have been reported, including; cumulative dose, administration schedule, mediastinal radiotherapy, old and young age, concurrent cardiovascular disease, combination therapy, gender, ethnicity and chromosomal abnormalities. Evaluation of left ventricular ejection fraction has been widely adopted as a means of monitoring and assessing anthracycline-induced cardiotoxicity. Biochemical markers and other techniques, such as endomyocardial biopsy, metaiodobenzylguanidine and indium-111-antimyosin scintigraphy are not routinely used. Methods employed to prevent cardiotoxicity include cumulative dose limitation, alteration of administration schedule, anthracycline analogues, liposomal formulations and the cardioprotective agent, dexrazoxane. With the growing number of paediatric malignancy survivors and the increasing use of anthracyclines in the adjuvant treatment of breast cancer, the cardiotoxicity associated with these agents will remain a formidable issue for physicians. Further work is required to identify patients at increased risk of cardiotoxicity and to develop novel methods of protecting and treating this adverse effect.

Evaluation of acute and early cardiotoxicity in survivors of Hodgkin's disease treated with ABVD or BEACOPP regimens

The study was conducted to compare the presence of cardiotoxicity after the treatment of Hodgkin's disease with the standard ABVD or BEACOPP protocol. We examined 29 patients treated by means of the ABVD regimen and 34 treated with the BEACOPP regimen. Using rest echocardiography we assessed the left ventricular function before and after the therapy. One year after the completion of therapy, a control examination was performed with a battery of tests; the rest and dynamic stress echocardiography and cardiopulmonary tests were carried out to assess cardiopulmonary performance. A similar significant deterioration of ejection fraction and diastolic function was apparent after the treatment in both sub-groups with a further progression at the one-year control. Only one patient from the BEACOPP sub-group showed a pathological drop of EF <50%. The most affected parameters of left ventricular function (LV) were Doppler indices. We found a significant relationship of the parameters of LV function compared with age, the cumulative dose of doxorubicin and the cumulative dose of radiotherapy. Multivariate analysis demonstrated that diastolic dysfunction correlated with advanced age and the cumulative dose of doxorubicin, and decreased cardiopulmonary performance with advanced age, radiotherapy, and female gender. Both parameters were significantly influenced by the presence of hypertension. The used regimens demonstrated similar subclinical cardiotoxicity, thus the most aggressive regimen, BEACOPP, is not accompanied by a higher rate of cardiac impairment. The clinical value of such subclinical cardiotoxicity will be estimated in a further prospective follow-up.

Cardiotoxicity induced by chemotherapy and antibody therapy

Modern cancer therapy employs a combination of chemotherapy, antibody-based therapy, radiotherapy, and surgery to prolong life and provide cure. However, many of the chemotherapy agents and antibodies, either singly or in combination, can affect the cardiovascular system. Common cardiovascular manifestations of these therapies include heart failure, ischemia, hypotension, hypertension, edema, QT prolongation, bradyarrhythmia, and thromboembolism. The patient's age, underlying cardiovascular status, and genetic background, as well as the route of drug administration and dosage, can all contribute to the development of cardiotoxicity. Strategies to monitor for and to manage these effects are discussed in this review.

Physiologic aspects of aging: impact on cancer management and decision making, part I

A gradual diminution in the physiologic reserve or functional capacity over time is the characteristic hallmark of aging, and this has a direct impact on the choice of cancer therapy and its toxicity profile in elderly patients with cancer. With the expected rapid rise of the older population as a subgroup, oncologists will increasingly treat elderly patients. Provision of competent care to this increasing pool of older patients with cancer necessitates that oncology professionals become familiar with age-associated changes in organ physiology and their impact on cancer treatment and toxicity. In this comprehensive review, we have listed changes in cardiovascular, gastrointestinal, pulmonary, and renal physiology with aging. Also enumerated is the impact of these changes on cancer therapy and toxicity in each organ system-based section. Cardiovascular changes primarily lead to reduction of the cardiac functional reserve, with a consequent increase in the risk of congestive heart failure. Changes in gastrointestinal physiology lead to increased mucosal damage. A reduction in pulmonary reserve has implications for postradiation complications, and a decline in renal function leads to an increased potential for nephrotoxicity. These changes impair the ability of older patients with cancer to tolerate cancer therapy and increase their risk of toxicities. This may lead to an overall decline in functional status, resulting frailty, poor quality of life, and ultimately poor outcomes. Becoming familiar with age-related physiologic changes is the first step for oncologists seeking to better tailor their treatments. This, combined with adoption of some of the clinical interventions suggested in this review, can help better manage the geriatric oncology patient. Further research is necessary for the development of more specific evidence-based recommendations.

Cardiovascular complications of cancer therapy: diagnosis, pathogenesis, and management

The cardiotoxicity of anticancer agents can lead to significant complications that can affect patients being treated for various malignancies. The severity of such toxicity depends on many factors such as the molecular site of action, the immediate and cumulative dose, the method of administration, the presence of any underlying cardiac condition, and the demographics of the patient. Moreover, toxicity can be affected by current or previous treatment with other antineoplastic agents. Cardiotoxic effects can occur immediately during administration of the drug, or they may not manifest themselves until months or years after the patient has been treated. In this article we review commonly used chemotherapy agents, including several recently approved medications, for their propensity to cause cardiotoxicity. Further research will be required to more accurately predict which patients are at risk for developing cardiotoxicity. In addition, management plans, as well as strategies to reduce cardiotoxicity, need to be developed.

Ultrasonic analysis of anthracycline-induced myocardial damage using cyclic variation of integrated backscatter

To test the feasibility of integrated backscatter (IB) for detecting anthracycline cardiotoxicity, we performed conventional echocardiography and IB analysis. For interindividual comparison, 32 patients with non-Hodgkin's lymphoma and 14 control subjects were selected. Of the patients, 10 had been treated with doxorubicin doses of </=200 mg/m(2) (low dose), 15 with </=400 mg/m(2) (moderate dose), and 7 with >400 mg/m(2) (high dose). In intraindividual comparison, 8 patients were examined before doxorubicin therapy and at a dose of 100 mg/m(2) and 8 were examined before and at a 300-mg/m(2) dose. Cyclic variation of IB (CV-IB) was obtained at the left ventricular posterior wall, using a modified, commercially available system in M-mode format. In interindividual comparison, CV-IB in high- and moderate-dose groups was smaller. In intraindividual comparison, CV-IB decreased after treatment with 300 mg/m(2) of doxorubicin. CV-IB was affected in some patients treated with a moderate dose of doxorubicin. IB analysis may be helpful for detecting early anthracycline cardiotoxicity.

Concomitant impairment of left ventricular systolic and diastolic function during doxorubicin therapy: a prospective radionuclide ventriculographic and echocardiographic study

Thirty adult lymphoma patients were studied prospectively with serial radionuclide ventriculography (RVG) and echocardiography (ECHO) to investigate whether changes in left ventricular (LV) diastolic function precede the impairment of LV systolic function during doxorubicin therapy. The patients received 8-10 cycles of CHOP to a cumulative doxorubicin dose of 400-500 mg/m2. RVG and ECHO were performed at baseline and after cumulative doxorubicin doses of 200, 400 and 500 mg/m2. Left ventricular ejection fraction (LVEF) decreased from 58 +/- 1.3 to 49.6 +/- 1.7% (p < 0.001) and from 58 +/- 1.7 to 52.5 +/- 1.3% (p = 0.036) as assessed with RVG and 2D ECHO, respectively. Of the diastolic ECHO doppler indices peak E wave velocity decreased from 63.3 +/- 3.2 to 51.3 +/- 2.6 cm/s (p = 0.008) and LV filling during the first 1/3 of diastole (1/3FF) from 42.2 +/- 1.7 to 36.5 +/- 2.0% (p < 0.001). The decrease in LVEF was statistically significant after the cumulative doxorubicin dose of 200 mg/m2 as assessed with RVG and after 400 mg/m2 as assessed with 2D ECHO. The decrease in 1/3FF reached the statistical significance after the cumulative doxorubicin dose of 400 mg/m2 and the decrease in peak E wave velocity after 500 mg/m2. This study shows that during doxorubicin therapy there are significant changes both in systolic and diastolic LV function. In addition, these changes manifest at relatively low cumulative doxorubicin doses and occur concomitantly. Thus, the assessment of diastolic function provides no advantage over monitoring systolic function during doxorubicin therapy.

Chemotherapy-induced cardiotoxicity: current practice and prospects of prophylaxis

Cardiotoxicity is a potential side effect of few chemotherapeutic agents. The anthracycline class of cytotoxic antibiotics are the most famous, but other chemotherapeutic agents can also cause serious cardiotoxicity and are not so well recognised. Examples include cyclophosphamide, ifosfamide, mitomycin and fluorouracil. Prediction and hence prophylaxis has always been a difficult task. Ideal monitoring techniques, upon which efficient prophylaxis depends, are yet to be determined. Current prophylaxis relies upon early detection of systolic and/or diastolic dysfunction. While somewhat useful, in some cases by the time defects are detected progression of chemotherapy-induced cardiomyopathy is beyond prevention. Prophylaxis would be much more efficient if a biochemical marker of myocardiocyte damage could be reliably used to stop further chemotherapy at the correct time before irreversible progressive 'macroscopic' damage becomes evident upon imaging. Work is currently progressing to identify the role of markers such as troponins and natriuretic peptides in this regard.

Frequency and risk factors of subclinical cardiotoxicity after anthracycline therapy in children: a systematic review

BACKGROUND

The aim of this systematic review was to summarise and appraise the published evidence with regard to the frequency and risk factors of subclinical cardiotoxicity in apparently healthy survivors of childhood cancer after anthracycline therapy.

PATIENTS AND METHODS

A search was made in Medline for studies published between 1966 and May 2001 that included >50 children and reported on the frequency of measures of subclinical cardiotoxicity. Information about the studies was abstracted by two reviewers and a validity score was calculated for each study.

RESULTS

The reported frequency of subclinical cardiotoxicity varied between 0% and 57% in the 25 studies included. Differences in outcome definitions of subclinical cardiotoxicity and differences in study patients with respect to the dose of anthracycline seemed to explain part of the wide variance of the frequency of subclinical cardiotoxicity. Fourteen of the 25 studies showed serious methodological limitations.

CONCLUSIONS

The reported frequency of subclinical cardiotoxicity shows a wide variation. Well designed studies with accurate and precise outcome measurements in well described groups of patients, after a sufficiently long follow-up period, are needed to obtain more insight into the frequency and importance of risk factors, and the clinical consequences of anthracycline-related subclinical cardiotoxicity.

Detection of anthracycline-induced cardiotoxicity

The use of anthracyclines, a group of potent anti-cancer agents incorporated into the treatment of a wide variety of solid and haematological tumours, is limited by its cardiotoxicity that can result in congestive heart failure (CHF). The best method to detect cardiotoxicity at an early stage in order to prevent severe deterioration, is still an unsolved problem. Although endomyocardial biopsy is considered to be the most sensitive and specific test for this purpose, its use is limited by its invasiveness. In daily practice, oncologists make use of parameters of systolic function (left ventricular ejection fraction, or fractional shortening) to detect cardiotoxicity, but these methods are not able to identify cardiotoxicity at an early stage. Based on increasing knowledge into the pathophysiology of anthracycline-induced cardiotoxicity and heart failure in general, new methods including the determination of diastolic function parameters, anti-myosin scintigraphy, assessment of heart rate variability, and the determination of biochemical markers have been proposed to identify patients at risk of the development of CHF in an early stage. However, most of these newer methods have not yet been adequately evaluated to allow them to be recommended for use in routine clinical practice.