Anthracycline Toxicity

Etiology

The specific mechanisms of anthracycline toxicity are still being elucidated; the underlying pathways will likely be complex, multifactorial, and interconnected. The currently accepted etiological mechanisms can be separated into a nuclear-mediated pathway and a mitochondrial-mediated pathway. Anthracycline toxicity appears to be dose-dependent and cumulative. This may be due to mitochondrial-mediated bioenergetic failures, the cumulative effect of cardiomyocyte death, the epigenetic disruption of gene expression through a combination of nuclear-mediated and mitochondrial-mediated cellular damage, or a combination of these mechanisms.[8]

Nuclear-Mediated Cardiomyocyte Death

The proposed primary anticancer mechanism of anthracycline chemotherapy is the disruption of topoisomerase II (TOP2) stable intermediates, specifically TOPIIβ. Given the role of TOP2 in managing double-stranded DNA breaks, this disruption can lead to escalating unresolved DNA damage, inhibiting normal cellular processes. There is also downstream induction of mitochondrial dysfunction due to altered gene expression, which, when combined with DNA damage from TOP2 and direct intercalation of anthracycline into the DNA helix, instigates p53-mediated apoptosis.[9] However, if the anthracycline molecule cannot enter the cell nucleus and cannot interfere with genetic expression, a reduction in toxicity and apoptosis occurs. Interestingly, restricting anthracycline from the nucleus does not prevent apoptosis, demonstrating how nuclear-mediated and mitochondrial-mediated pathways co-contribute to cardiomyocyte death.[10] 

Mitochondrial-Mediated Cardiomyocyte Death

The role of reactive oxygen species (ROS), which may also determine some of the anticancer properties of the anthracycline class, may cause mitochondrial dysfunction in highly metabolic cells that display reduced antioxidant networks, such as the cardiomyocyte. As the cardiomyocyte rapidly takes up an anthracycline molecule, it undergoes a redox cycle via the NADH pathway, generating ROS and semiquinone free radicals.[11] Redox cycling, mainly when accumulated within the abundant cardiomyocyte mitochondria, significantly increases oxidative stress. The Fenton cycle, which occurs in the presence of mitochondrial iron, can further propagate this cycle. The downstream peroxidation of lipids and proteins due to increased oxidative stress increases cellular dysfunction and enzyme failure and impairs oxidative phosphorylation.[12] Specifically, anthracyclines in the mitochondrion promote the dissociation of cardiolipin from cytochrome-C, which in turn causes mitochondrion-initiated apoptosis.[13] 

Anthracyclines demonstrate a dose-dependent ability to alter the mitochondrial membrane permeability (MMP). This process is calcium- and redox-dependent, with mitochondrial iron playing a pivotal role. As MMP increases, the inability to maintain electrochemical gradients impairs mitochondrial function, promoting cellular respiration failure and necroptosis.[14] The increase in MMP also induces the release of apoptosis-inducing factor (AIF) and promotes cellular death through caspase-independent mechanisms separate from the cytochrome-C mechanism previously described; this is known as ferroptosis.

Epidemiology

The epidemiological data on anthracycline toxicity is impacted by the dose-dependent nature of the toxicity and the variable presence of risk factors associated with its development, including many environmental and genetic factors. The data are further compounded by clinician variance in echocardiographic determination of left ventricular ejection fraction (LVEF) and a need for survivorship to demonstrate disease.[15] As a result, there is a high degree of variance between studies demonstrating anthracycline toxicity. The consensus is to define anthracycline toxicity as an LVEF that falls below 40% or reduces more than 10% from the pretreatment baseline. When doses are mentioned, these are considered equivalent doses of doxorubicin, the most commonly administered anthracycline chemotherapeutic agent. 

Children

More than 50% of children with cancer receive anthracycline chemotherapy; exposure above 250 mg/m² is associated with a 10% incidence of anthracycline toxicity, rising to a 30% incidence when accumulated doses exceed 600 mg/m².[16] When the risk is grouped, a low-risk patient with less than a 250 mg/m² accumulative dose has a 0.5% incidence of heart failure by age 40 years, compared to a high-risk patient with more than a 250 mg/m² accumulative dose who has an 11.7% incidence of heart failure at the age of 40. Notable risk factors for developing anthracycline toxicity include patient age at treatment younger than 5 years, female gender, chest radiation, diabetes, or hypertension.[17] If the incidence of childhood cancer were estimated at 15 per 100,000 per annum, this would lead to a population incidence of less than 1 per 100,000 children per annum developing significant anthracycline toxicity in the United States.

Adults

The use of anthracycline chemotherapy in adults is gradually declining with the development of newer agents. However, anthracycline-containing chemotherapeutic regimens remain commonplace; up to 70% of older adults with lymphoma receive anthracycline chemotherapy.[18] Anthracycline-associated heart failure develops in adults, most notably between cumulative anthracycline doses of  400 to 550 mg/m². At cumulative doses between 250 and 400 mg/m^2, the incidence of heart failure is between 3% and 5%. At cumulative doses of 550 mg/m², the incidence of heart failure rises to between 7% and 26%, and at a cumulative dose of 700 mg/m², the incidence is as high as 48%.[19] The currently recommended maximum safe anthracycline dose for any patient is 400 to 450 mg/m²; most treatment protocols advise against higher doses. 

Enhanced cardiac imaging may identify changes resulting from anthracycline chemotherapy in patients who do not develop symptoms. More than 90% of patients treated with an anthracycline medication manifest myocardial changes on biopsy at cumulative doses above 240 mg/m², and the most significant asymptomatic changes in cardiac function occur at cumulative doses greater than 400 mg/m².[20] If LVEF is assessed via multi-gated acquisition (MUGA) in asymptomatic patients when the cumulative dose is less than 400 mg/m², the average LVEF reduction is 4%. Where doses exceed 400 mg/m², the average LVEF reduction is 15%. 

The incidence of anthracycline-induced cardiotoxicity at similar cumulative exposures increases with age; 14.9% of patients between 40 and 59 years of age receiving a cumulative doxorubicin dose of 600mg/m² develop cardiotoxicity, but 22.4% of adults greater than 60 years of age develop cardiotoxicity at the same cumulative dose.[21] Significant risk factors for the development of anthracycline-induced cardiotoxicity include patient age, male gender, concurrent or historical chest radiation therapy, the presence of the classic predictors of heart disease, a prior reduction in LVEF, or concurrent treatment with cyclophosphamide, paclitaxel, or human epidermal growth factor receptor 2 (HER2) therapies.[22] 

Pathophysiology

Anthracycline toxicity induces myocardial cell death via multiple mechanisms, resulting in globalized systolic and diastolic dysfunction and dilated cardiomyopathy. This ionotropic failure reduces cardiac output, increases cardiac preload, and causes pulmonary and systemic circulatory congestion. Decreased renal perfusion activates the renin-angiotensin-aldosterone (RAAS) pathway, resulting in compensatory vasoconstriction and increased blood volume, exacerbating vascular congestion.[23]

Histopathology

Endomyocardial biopsy with histological evaluation is seldom required to evaluate and manage anthracycline-induced cardiotoxicity. Reduced left ventricular mass and dilated cardiac chambers are often appreciated macroscopically. However, a microscopic assessment of the anthracycline-damaged heart will reveal diffuse myocardial fibrosis, interstitial edema, myocyte vacuolization, and atrophy; evidence of thrombosis and vascular dysfunction may also be seen.[24] The presence of normal coronary vasculature excludes ischemic cardiomyopathy and the lack of typical inflammatory infiltrates excludes myocarditis, facilitating a diagnosis of anthracycline-induced cardiotoxicity as a diagnosis of exclusion in the proper clinical context.[25]

Toxicokinetics

Anthracyclines demonstrate an apparent volume of distribution of approximately 25 L/kg, indicative of extensive tissue uptake.[26] Anthracyclines have a triphasic half-life and are predominately metabolized by the liver; 80% of the anthracycline dose is excreted in bile.[26] Patients with concomitant liver disease may have a reduced rate of anthracycline excretion and an increased risk of toxicity; liver dysfunction is commonly seen in various malignancies. If serum bilirubin levels are elevated, the anthracycline dose may need to be reduced.[27] 

The recommended maximum cumulative exposure to anthracycline chemotherapy is 450 mg/m²; patients with risk factors for anthracycline toxicity should receive a maximum cumulative dose of 400 mg/m² or less. The inadvertent administration of a single toxic dose of anthracyclines is associated with increased myelosuppressive side effects without anthracycline cardiotoxicity.[28] The delivery method, be it a continuous or bolus infusion, does not affect the toxicity outcomes significantly.[29]

The formulation of anthracycline notably affects its pharmacokinetics; liposomal formulations have a significantly longer half-life of greater than 70 hours compared to approximately 30 hours for conventional formulations. However, liposomal formulations are associated with a lower incidence of cardiotoxicity despite the longer half-life.

History and Physical

History

The manifestations of anthracycline cardiotoxicity are consistent with the typical symptoms of heart failure—those of congestion and those of reduced ionotropy. Symptoms of congestion include but are not limited to weight gain, dyspnea, paroxysmal nocturnal dyspnea, peripheral edema, ascites, cough, and orthopnea. Symptoms of reduced inotropy are typically more constitutional, including reduced exercise tolerance, decreased appetite, and fatigue. However, anthracycline cardiotoxicity may be asymptomatic. In patients with anthracycline cardiotoxicity, it is imperative to establish the cumulative exposure dose and when the drug was administered. 

It can be challenging to distinguish symptoms of cancer or chemotherapy treatment from those of anthracycline toxicity. Ascertaining associated cardiac risk factors is essential, and significant confounding differentials such as myocardial ischemia, pulmonary embolism, and myocarditis must be excluded. Palpitations can be a component of anthracycline toxicity; atrial fibrillation is potentially an early manifestation.

Physical Examination

Patients with subclinical anthracycline cardiotoxicity typically present without significant physical examination findings. Early and often subtle signs of cardiotoxicity include elevated jugular venous pressure, modest weight gain, and pedal edema. Cardiac congestion may result in hypertension or tachycardia; patients without congestion may be normo- or hypotensive. Daytime oliguria with nocturia may be reported. A recent weight increase secondary to fluid retention and third spacing is common. 

A diagnosis of anthracycline-induced cardiotoxicity is more forthcoming in the presence of frank cardiac failure characterized by elevated jugular venous pressure, tachypnea, tachycardia, and pedal edema. Sacral edema, ascites, pleural effusions, and pulmonary edema with respiratory compromise and cyanosis may be present. An S3 or S4 may be heard during cardiac auscultation. Point-of-care ultrasound may reveal globally reduced myocardial contractility with dilated cardiac chambers; the characteristic features of elevated central venous pressure, including a dilated or plethoric inferior vena cava without inspiratory collapse, increased portal vein pulsatility, and reversal of the hepatic Doppler waveform, may be present.

Evaluation

Specific patient cohorts are at increased risk of anthracycline cardiotoxicity. Before commencing anthracycline chemotherapy, all patients must undergo baseline investigations for risk stratification. At a minimum, these investigations include an electrocardiogram, transthoracic echocardiogram, serum troponin, and serum N-terminal pro-brain natriuretic peptide (NT-proBNP). All patients must also undergo some form of cardiac imaging; 3-dimensional (3D) transthoracic echocardiography, cardiac computed tomography (CT), or cardiac magnetic resonance imaging (cMRI) with strain-encoding are preferred. Multi-gated acquisition (MUGA) scanning is considered a fourth-line option due to its lack of structural detail.[30] It is unsafe to proceed with anthracycline chemotherapy before definitive cardiac imaging is obtained. 

Determining the Risk of Anthracycline-Induced Cardiotoxicity

Online resources such as the calculator developed by the Cardio-Oncology Study Group of the Heart Failure Association of the European Society of Cardiology in collaboration with the International Cardio-Oncology Society (HFA-ICOS) are available to assist in determining anthracycline toxicity risk. 

Category 1: Moderate-Risk (Assign 1 point per risk factor)

• Active smoker
• Obesity
• Prior non-anthracycline chemotherapy exposure
• Diabetes
• Hypertension
• Chronic kidney disease
• Elevated baseline troponin or NT-proBNP

Category 2: Moderate-Risk (Assign 2 points per risk factor)

• Low-normal left ventricular ejection fraction (50-54%)
• Prior non-anthracycline chemotherapy exposure
• Age between 65 and 79 years

High-Risk

• Subclinical or impaired left ventricular ejection fraction impairment (<50%)
• Severe valvular heart disease
• Prior ischemic cardiac disease
• Stable angina
• History of radiotherapy to the mediastinum
• Age greater than 80 years

Very-High-Risk

• Heart failure
• Prior anthracycline toxicity

A patient at low risk of anthracycline-induced cardiotoxicity presents with no more than a single Category 1 risk factor. A patient with a total score of 2, 3, or 4 points after assessment of risk factors is considered to be at moderate risk of anthracycline-induced cardiotoxicity. A patient with a total score of 5 points or greater or the presence of any single high-risk factor is deemed to be at high risk of anthracycline-induced cardiotoxicity. Patients who have any very high-risk factors are considered to be at very high risk of anthracycline-induced cardiotoxicity.[31]  

Continuing Evaluation During and After Anthracycline Chemotherapy

The diagnostic consensus is that a reduction of left ventricular ejection fraction (LVEF) of greater than 10% in the presence of anthracycline chemotherapy or an absolute reduction of LVEF to less than 40% is consistent with a diagnosis of anthracycline toxicity. Further evaluation, such as angiography or cMRI, may be required to exclude disease processes that may mimic anthracycline-induced cardiotoxicity.[32]

Consideration of repeat cardiac imaging is imperative for all patients after they exceed a cumulative anthracycline chemotherapy dose of 250 mg/m². Repeat cardiac imaging should be performed for any patients who develop symptoms suggestive of anthracycline-induced cardiotoxicity at any point during treatment. Repeat cardiac imaging should be performed on all patients 12 months after completion of anthracycline chemotherapy, regardless of cumulative dose. Of patients who develop anthracycline-induced cardiotoxicity, 98% will have an abnormal transthoracic echocardiogram, and 71% of them will not recover completely.[33] However, the data about how best to evaluate patients for anthracycline-induced cardiotoxicity is sparse and of low quality; high-quality evidence exists only for patients deemed to be at high or very high risk before initiation of anthracycline chemotherapy.

Patients initially deemed to be at low or moderate risk for anthracycline-induced cardiotoxicity should undergo laboratory evaluation of serum cardiac biomarkers every 2 cycles. Patients initially considered to be at moderate risk for anthracycline-induced cardiotoxicity should also undergo repeat cardiac imaging 3 months following the initiation of anthracyline chemotherapy. However, there is low-quality evidence to support the use of biomarkers in low- to moderate-risk patients.[34] Patients initially deemed to be at high or very high risk for anthracycline-induced cardiotoxicity should undergo serum cardiac biomarker testing at every cycle and cardiac imaging every other cycle. Rising serum biomarkers during routine monitoring should prompt cardiac imaging in all cases. 

Patients who undergo hematopoietic stem-cell transplantation and anthracycline chemotherapy have a significantly increased rate of delayed-onset anthracycline-induced cardiotoxicity, with presentations frequently occurring more than 1 year after completion of anthracycline chemotherapy. These patients should undergo cardiac imaging every 3 to 5 years regardless of symptomatology.[35] Additionally, patients who have received more than 250 mg/m² of anthracycline should undergo cardiac imaging with transthoracic echocardiography every 5 years for their lifetime. Transthoracic echocardiography should include global longitudinal strain (GLS) with speckle tracking whenever possible; this advanced modality sensitively assesses longitudinal contraction, and a reduction in GLS of 15% or more strongly correlates with an impending significant reduction in LVEF.[36]

Unique Populations

Evaluating the risk of anthracycline-induced cardiotoxicity in adults treated with anthracycline without toxicity as children is complex and patient-dependent. For most patients, annual risk screening focusing on primary prevention is recommended, with immediate cardiology consultation when pregnancy occurs. Adults who received a cumulative dose of anthracycline greater than 250 mg/m² in childhood should undergo cardiac imaging every 2 years; those with a lower cumulative dose should undergo cardiac imaging every 5 years.[30] 

Regular cardiac imaging during childhood cancer treatment with anthracycline chemotherapy is recommended, as is performing cardiac imaging every 5 years, with the first imaging study within 2 years of therapy or when pregnancy occurs, whichever happens first. These recommendations are based mainly on evaluation consensus.[16]

Treatment / Management

Patients undergoing anthracycline chemotherapy who are deemed to be at high or very high risk of anthracycline-induced cardiotoxicity should be prescribed the minimum dose of anthracycline. Pretreatment initiation of high-dose statin therapy and angiotensin-converting enzyme inhibitors (ACEi), angiotensin receptor blockers (ARB), or beta-blockers in high- or very-high-risk patients should be considered to reduce anthracycline toxicity, LVEF impairment, and mortality.[37] This strategy can also be employed when a rise in serum cardiac biomarkers is noted. Beta-blockers with antioxidant activity, such as nebivolol and carvedilol, may be preferable.[38] Additional preventative therapies may be indicated in patients with significant toxicity risk and are discussed in the Toxicity and Adverse Effect Management section.(A1)

The clinical symptomatology and cardiac imaging results dictate the management of anthracycline toxicity. Toxicity is deemed mild, moderate, or severe and defined as:

• Mild toxicity: LVEF is reduced but remains above 50%, or GLS is decreased by more than 15%
• Moderate toxicity: LVEF is between 40% and 50%
• Severe toxicity: LVEF is less than 40%

Asymptomatic Anthracycline Toxicity

• Mild toxicity should be managed with cardioprotective therapy in the form of ACEi/ARB and beta-blockers. Escalated monitoring should be considered while anthracycline chemotherapy continues. 
• Moderate toxicity should prompt an interruption in anthracycline chemotherapy and the commencement of heart failure therapy.
• Severe toxicity should prompt an interruption in anthracycline chemotherapy and the commencement of heart failure therapy.

Symptomatic Anthracycline Toxicity

• Mild toxicity should prompt consideration of interrupting anthracycline chemotherapy; heart failure therapy should be initiated.
• Moderate toxicity should lead to the immediate interruption of anthracycline chemotherapy and should not be reinitiated until there is an improvement in LVEF with heart failure therapy. 
• Severe toxicity should initiate the immediate cessation of anthracycline chemotherapy; the medication should not be reconsidered. 

Heart failure therapy should be commenced in any symptomatic patient or asymptomatic patient with a significant LVEF reduction. In addition to ACEi/ARB and beta-blocker therapy that alters the RAAS pathway and neurohormonal dysregulation in cardiac failure, patients should begin the following therapy unless otherwise contraindicated; this therapy does not include diuretic treatment, which may be required to manage additional symptoms of cardiac congestion.[39] 

• Mineralocorticoid receptor antagonists 
• Angiotensin receptor-neprilysin inhibitors  - these should not be co-administered with ACEi/ARB therapy. 
• Sodium-glucose transport protein 2 inhibitors (SGLT2i)

Patients with severe cardiac failure require specialist consultation. Alternative medical therapy with medications such as ivabradine or digoxin may be necessary. Patients with severe cardiac failure and conduction abnormalities, including bundle branch blocks with wide QRS intervals, may require device implantation for cardiac resynchronization therapy, although this is atypical. Left ventricular assist devices and heart transplantation are rarely offered to patients with anthracycline toxicity due to their ongoing risk of malignancy.[40] To date, less than 5% of heart transplants have been provided to patients with anthracycline toxicity, albeit long-term outcomes when transplantation is performed are comparable.[41] 

Cardiac rehabilitation in high-intensity interval training can improve cardiovascular outcomes in patients with anthracycline toxicity and can be offered to all suitable patients.[42] Cardiac rehabilitation programs specific to anthracycline toxicity are not available. Controlling modifiable risk factors before, during, and after anthracycline toxicity improves outcomes. All patients should be informed of the benefits of tobacco and alcohol cessation, optimal control of chronic diseases such as hypertension and diabetes, and diet and exercise. (B2)

Differential Diagnosis

Dilated cardiomyopathy resulting from anthracycline toxicity is diagnostically nonspecific if not correlated with clinical history, as are the associated endomyocardial biopsy and cMRI findings. It is essential to consider concomitant and potentially reversible causes of cardiomyopathy that may confound a diagnosis; these include but are not limited to myocarditis and thyrotoxic, ischemic, and alcohol-induced cardiomyopathy.

The differential diagnosis of anthracycline toxicity may be confounded by the concomitant use of alternative cardiotoxic chemotherapy agents, including HER2 therapy and immune checkpoint inhibitors. Anthracycline-containing chemotherapy regimens may include cyclophosphamide, which is also associated with potent cardiotoxicity. Radiotherapy to the chest cavity may cause various cardiac complications, including changes to the pericardium, the cardiac valves, and dilated cardiomyopathy. Anticancer therapy is often given in close succession; determining the root cause of dilated cardiomyopathy may be challenging and require specialist and multidisciplinary input. 

In clinical practice, recent anthracycline exposure with a reduction in cardiac function compared to prior cardiac imaging strongly supports the clinical diagnosis of anthracycline toxicity. Due to the improved utilization of cardiac evaluation before, during, and after anthracycline therapy, the presentation of undiagnosed anthracycline toxicity long after the initial treatment is rare, excluding underlying genetic or idiopathic causes. The diagnosis of idiopathic dilated cardiomyopathy should not be made if cardiotoxic medications have recently been administered and prior cardiac imaging revealed no abnormalities.

Toxicity and Adverse Effect Management

Given the potentially significant consequences of anthracycline toxicity, efforts have been made to create less toxic analogs that still provide anthracycline anticancer properties to the tumor.

Molecular Modification

Likely, the anthracycline molecule cannot be significantly altered to prevent toxicity without impacting anticancer function. Camsirubicin is a synthetic doxorubicin analog that exhibits some selectivity for the TOPIIα isoform; clinical studies have demonstrated similar profiles in cancer cytotoxicity with reduced anthracycline-induced cardiotoxicity. Annamycin is a highly lipophilic anthracycline that has shown preferential accumulation in the lungs and reduced cardiotoxicity in early trials.[43]

Anthracycline formulations can be modified through liposomal infusion, restricting the ability of the molecule to cross tighter vascular junctions, such as those found in the myocardium, reducing anthracycline exposure and the risk of toxicity. Liposomal infusions may, however, limit anthracycline anticancer properties, and toxicity may still occur in high-risk patients.[44] Prescribing liposomal anthracycline preparations is the next best option after reducing the cumulative dose to reduce the incidence of anthracycline toxicity.

Iron Chelation

Dexrazoxane employs iron chelation to prevent ROS formation and disturb anthracycline-induced TOP2 binding. Dexrazoxane, in combination with anthracycline chemotherapy, has been shown to significantly lower the incidence of LVEF reduction compared to anthracycline therapy alone; this medication remains reserved for high-risk patients when anthracycline chemotherapy is essential.[45] Although other iron-chelating agents have been shown to provide similar effects, dexrazoxane is the only medication regularly used to prevent anthracycline-induced cardiotoxicity. Iron chelation may lower the anticancer benefit of anthracyclines, and dexrazoxane is associated with myelosuppression when combined with a wide variety of anticancer agents. 

Prognosis

Patients exposed to anthracycline chemotherapy are much more likely to die from their underlying malignancy before anthracycline toxicity presents a threat to life. More than 95% of patients with cancer treated with anthracycline chemotherapy die from their underlying malignancy rather than developing anthracycline toxicity, and cardiac death contributes to 0.7% all-cause mortality.[33] At 1 year following anthracycline treatment, 98% of cases where toxicity develops will be clinically apparent. Approximately 11% of patients note a full recovery of their cardiac function, significantly increased by early and proactive intervention; 71% see an incomplete recovery, and the remaining 18% see no significant recovery in cardiac function. Patients with partial to no recovery in cardiac function have higher New York Heart Association classifications, impacts on quality of life, and incidence of cardiac death.[33] In high-dose anthracycline chemotherapy, where severe symptoms of cardiotoxicity present during treatment, cardiac failure is an associated cause of death in up to 38% of patients, with a median survival of 162 days.[46]

Concerning longer-term cancer versus cardiac outcomes, only after 9 years following the first presentation with cancer does the cardiac cause of death overtake malignancy, including relapse and secondary cancer. Patients with lower cancer stages have an increased relative incidence of death due to reduced cancer mortality.[47] The overall prognosis of a patient with anthracycline-induced cardiotoxicity is similar to that of dilated cardiomyopathy of any cause, in which 5-year survival is quoted at 86%, compared to 88% in idiopathic cardiomyopathy. Patients with anthracycline toxicity are affected more significantly by refractory heart failure with reduced incidence of sudden death than those with idiopathic cardiomyopathy.[48]

In cases of childhood cancer, cardiac cause of death in anthracycline toxicity remains rare at less than 0.5% incidence during anthracycline chemotherapy; this includes patients exposed to high doses when anthracycline toxicity on cardiac imaging is noted, and patients also appear to require fewer cardiac devices.[49] To this end, cardiac cause of death has an incidence of 0.14% following 30-year survivorship for childhood cancer, even in cases of high-dose anthracycline and impaired cardiac function.[50]

Complications

The complications associated with anthracycline-induced cardiotoxicity are consistent with those of dilated cardiomyopathy of other etiology.

Pericardial effusions have been noted in patients who have received anthracycline chemotherapy, although the incidence is low. The exact etiology of these effusions is unclear. Anthracycline toxicity can predispose to supraventricular tachyarrhythmias, including atrial fibrillation and atrial flutter. The incidence of these tachyarrhythmias is 10% to 15% in subclinical anthracycline toxicity and is similar to other forms of dilated cardiomyopathy when reductions in LVEF are significant.[19] The risk of arrhythmia increases with the severity of anthracycline toxicity; severe and life-threatening ventricular arrhythmias are rare. There appears to be no significant increase in the risk of ischemic or valvular heart disease as found in other chemotherapy toxicity syndromes. 

Pregnant patients with anthracycline-induced cardiotoxicity have a very high incidence of cardiovascular events. However, the complication rates in those with all-cause peripartum cardiomyopathy are notably high. There is no increase in maternal deaths associated with anthracycline toxicity compared to other causes of peripartum cardiomyopathy.[51]