Subclinical cardiac dysfunction and exercise performance in childhood cancer survivors

Association of European Paediatric and Congenital Cardiology practical recommendations for surveillance and prevention of cardiac disease in childhood cancer survivors: the importance of physical activity and lifestyle changes From the Association of European Paediatric and Congenital Cardiology Working Group Sports Cardiology, Physical Activity and Prevention, Working Group Adult Congenital Heart Disease, Working Group Imaging and Working Group Heart Failure

BACKGROUND

Childhood cancer survivors are at increased risk of developing cardiovascular diseases, presenting as the main causes of morbidity and mortality within this group. Besides the usual primary and secondary prevention in combination with screening during follow-up, the modifiable lifestyle factors of physical activity, nutrition, and body weight have not yet gained enough attention regarding potential cardiovascular risk reduction.

OBJECTIVE

These practical recommendations aim to provide summarised information and practical implications to paediatricians and health professionals treating childhood cancer survivors to reduce the risk of cardiovascular late effects.

METHODS

The content derives from either published guidelines or expert opinions from Association of European Paediatric and Congenital Cardiology working groups and is in accordance with current state-of-the-art.

RESULTS

All usual methods of prevention and screening regarding the risk, monitoring, and treatment of occurring cardiovascular diseases are summarised. Additionally, modifiable lifestyle factors are explained, and clear practical implications are named.

CONCLUSION

Modifiable lifestyle factors should definitely be considered as a cost-effective and complementary approach to already implemented follow-up care programs in cardio-oncology, which can be actively addressed by the survivors themselves. However, treating physicians are strongly encouraged to support survivors to develop and maintain a healthy lifestyle, including physical activity as one of the major influencing factors. This article summarises relevant background information and provides specific practical recommendations on how to advise survivors to increase their level of physical activity.

Surveillance cardiopulmonary exercise testing can risk-stratify childhood cancer survivors: underlying pathophysiology of poor exercise performance and possible room for improvement

BACKGROUND

Asymptomatic childhood cancer survivors (CCS) frequently show decreased exercise performance. Poor exercise performance may indicate impaired future cardiovascular health.

METHODS

Cardiopulmonary exercise testing (CPET) was performed in asymptomatic off-treatment CCS (age ≥ 10 years). Patients were divided into Normal and Poor performance groups by %predicted maximum VO2 at 80%. Both peak and submaximal CPET values were analyzed.

RESULTS

Thirty-eight males (19 Normal, 19 Poor) and 40 females (18 Normal, 22 Poor) were studied. Total anthracycline dosage was comparable among 4 groups. The body mass index (BMI), although normal, and weight were significantly higher in Poor groups. Peak heart rate (HR) and peak respiratory exchange ratio (RER) were comparable in all four groups. Peak work rate (pWR)/kg, peak oxygen consumption (pVO2)/kg, peak oxygen pulse (pOP)/kg, and ventilatory anaerobic threshold (VAT)/kg were significantly lower, whereas heart rate (HR) increase by WR/kg (ΔHR/Δ[WR/kg] was significantly higher in Poor groups. Simultaneously plotting of weight & pVO2 and ΔHR/ΔWR & ΔVO2/ΔHR revealed a distinct difference between the Normal and Poor groups in both sexes, suggesting decreased skeletal muscle mass and decreased stroke volume reserve, respectively, in Poor CCS. The relationship between VAT and pVO2 was almost identical between the two groups in both sexes. Ventilatory efficiency was mildly diminished in the Poor groups.

CONCLUSIONS

Decreased skeletal muscle mass, decreased stroke volume reserve, and slightly decreased ventilatory efficiency characterize Poor CCS in both sexes. This unique combined CPET analysis provides useful clinical biomarkers to screen subclinical cardiovascular abnormality in CCS and identifies an area for improvement.

Systolic myocardial function measured by echocardiographic speckle-tracking and peak oxygen consumption in pediatric childhood cancer survivors-a PACCS study

Background

Cancer therapy-related cardiotoxicity is a major cause of cardiovascular morbidity in childhood cancer survivors. The aims of this study were to investigate systolic myocardial function and its association to cardiorespiratory fitness in pediatric childhood cancer survivors.

Methods

In this sub-study of the international study "Physical Activity and fitness in Childhood Cancer Survivors" (PACCS), echocardiographic measures of left ventricular global longitudinal strain (LV-GLS) and right ventricular longitudinal strain (RV-LS) were measured in 128 childhood cancer survivors aged 9-18 years and in 23 age- and sex-matched controls. Cardiorespiratory fitness was measured as peak oxygen consumption achieved on treadmill and correlated to myocardial function.

Results

Mean LV-GLS was reduced in the childhood cancer survivors compared to the controls, -19.7% [95% confidence interval (CI) -20.1% to -19.3%] vs. -21.3% (95% CI: -22.2% to -20.3%) (p = 0.004), however, mainly within normal range. Only 13% of the childhood cancer survivors had reduced LV longitudinal strain z-score. Mean RV-LS was similar in the childhood cancer survivors and the controls, -23.2% (95% CI: -23.7% to -22.6%) vs. -23.3% (95% CI: -24.6% to -22.0%) (p = 0.8). In the childhood cancer survivors, lower myocardial function was associated with lower peak oxygen consumption [correlation coefficient (r) = -0.3 for LV-GLS]. Higher doses of anthracyclines (r = 0.5 for LV-GLS and 0.2 for RV-LS) and increasing time after treatment (r = 0.3 for LV-GLS and 0.2 for RV-LS) were associated with lower myocardial function.

Conclusions

Left ventricular function, but not right ventricular function, was reduced in pediatric childhood cancer survivors compared to controls, and a lower left ventricular myocardial function was associated with lower peak oxygen consumption. Furthermore, higher anthracycline doses and increasing time after treatment were associated with lower myocardial function, implying that long-term follow-up is important in this population at risk.

Cardiopulmonary Exercise Testing Characterizes Silent Cardiovascular Abnormalities in Asymptomatic Pediatric Cancer Survivors

Late-onset cardiovascular complications are serious concerns for pediatric cancer survivors (PCS) including those who are asymptomatic. We investigated whether cardiopulmonary exercise testing (CPET) can delineate the underlying pathophysiology of preclinical cardiovascular abnormalities in PCS. We examined CPET data via cycle ergometer in asymptomatic PCS with normal echocardiogram and age-matched controls. Peak and submaximal parameters were analyzed. Fifty-three PCS and 60 controls were studied. Peak oxygen consumption (VO₂), peak work rate (WR), and ventilatory anaerobic threshold (VAT) were significantly lower in PCS than controls (1.86 ± 0.53 vs. 2.23 ± 0.61 L/min, 125 ± 45 vs. 154 ± 46 W, and 1.20 ± 0.35 vs. 1.42 ± 0.43 L/min, respectively; all p < 0.01), whereas peak heart rate (HR) and ventilatory efficiency (a slope of minute ventilation over CO₂ production or ∆VE/∆VCO₂) were comparable. Peak respiratory exchange ratio (RER) was significantly higher in PCS (p = 0.0006). Stroke volume (SV) reserve was decreased in PCS, indicated by simultaneous higher dependency on HR (higher ∆HR/∆WR) and lower peak oxygen pulse (OP). Twelve PCS with high peak RER (≥ 1.3) revealed lower pVO₂ and VAT than the rest of PCS despite higher ventilatory efficiency (lower ∆VE/∆VCO₂), suggesting fundamental deficiency in oxygen utilization in some PCS. Poor exercise performance in PCS may be mainly attributed to limited stroke volume reserve, but the underlying pathophysiology is multifactorial. Combined assessment of peak and submaximal CPET parameters provided critical information in delineating underlying exercise physiology of PCS.

Assessment of late cardiotoxic effects in patients treated for cancer in childhood

Graphical AbstractThe aim was to assess the late cardiotoxic effects in young adults treated for various cancer types in childhood using echocardiography and 24-h ECG Holter monitoring.

Exploring pulmonary function and physical function in childhood cancer: A systematic review

BACKGROUND

Children with cancer experience pulmonary and physical function side effects from the cancer itself and the medical interventions. This systematic review examines the known relationship between pulmonary function and physical function in childhood cancer and identifies gaps in the literature.

METHODS

A search of Ovid Medline, CINAHL (EbscoHost) and Embase to identify literature from 2009 to March 2020.

RESULTS

Fifty-seven studies met inclusion criteria. Thirty-seven studies reported impaired pulmonary function. Incidence of pulmonary dysfunction ranged from 45.5 % to 84.1 %. Eighteen studies reported impaired physical function. Three studies investigated the relationship between pulmonary function and physical function. No studies explored inspiratory muscle strength.

CONCLUSION

Pulmonary function and physical function are related and frequently impaired in children during and after cancer treatment. A literature gap was found in diaphragm function and its relationship with physical function. Future studies should focus on interventions that target the pulmonary mechanisms impacting physical function.

Exercise cardiovascular magnetic resonance reveals reduced cardiac reserve in pediatric cancer survivors with impaired cardiopulmonary fitness

BACKGROUND

Pediatric cancer survivors are at increased risk of cardiac dysfunction and heart failure. Reduced peak oxygen consumption (peak VO2) is associated with impaired cardiac reserve (defined as the increase in cardiac function from rest to peak exercise) and heart failure risk, but it is unclear whether this relationship exists in pediatric cancer survivors. This study sought to investigate the presence of reduced peak VO2 in pediatric cancer survivors with increased risk of heart failure, and to assess its relationship with resting cardiac function and cardiac haemodynamics and systolic function during exercise.

METHODS

Twenty pediatric cancer survivors (8-24 years; 10 male) treated with anthracycline chemotherapy ± radiation underwent cardiopulmonary exercise testing to quantify peak VO2, with a value < 85% of predicted defined as impaired peak VO2. Resting cardiac function was assessed using 2- and 3-dimensional echocardiography, with cardiac reserve quantified from resting and peak exercise heart rate, stroke volume index (SVI) and cardiac index (CI) using exercise cardiovascular magnetic resonance (CMR).

RESULTS

Twelve of 20 survivors (60%) had reduced peak VO2 (70 ± 16% vs. 97 ± 14% of age and gender predicted). There were no differences in echocardiographic or CMR measurements of resting cardiac function between survivors with normal or impaired peak VO2. However, those with reduced peak VO2 had diminished cardiac reserve, with a lesser increase in CI and SVI during exercise (Interaction P < 0.01 for both), whilst the heart rate response was similar (P = 0.71).

CONCLUSIONS

Whilst exercise intolerance is common among pediatric cancer survivors, it is poorly explained by resting measures of cardiac function. In contrast, impaired exercise capacity is associated with impaired haemodynamics and systolic functional reserve measured during exercise. Consequently, measures of cardiopulmonary fitness and cardiac reserve may aid in early identification of survivors with heightened risk of long-term heart failure.

Exercise testing and cardiac rehabilitation in patients treated for cancer

Cardiovascular disease (CVD) is a major competing cause of morbidity and mortality in patients with cancer. Cancer treatment can have detrimental short- and long-term cardiovascular effects. Moreover, cancer patients may have a significant loss in cardiorespiratory fitness, a key CVD risk factor, during and after cancer treatment. Exercise training has emerged as a potential intervention to improve fitness and reduce the risk of CVD in cancer. In this review, we discuss the role of cardiorespiratory fitness to predict cancer and CVD outcomes, as well as explore the impact of exercise training to improve fitness and other key outcomes in patients with cancer. The role of cardio-oncology rehabilitation will also be highlighted.

The 6-minute walk test is a good predictor of cardiorespiratory fitness in childhood cancer survivors when access to comprehensive testing is limited

Cardiovascular disease is up to 10 times more likely among childhood cancer survivors compared to siblings. Low cardiorespiratory fitness is a modifiable risk-factor for cardiovascular diseases. Yet, cardiorespiratory fitness is not routinely screened in pediatric oncology, and healthy VO2max cut-points are unavailable. We aimed to predict cardiorespiratory fitness by developing a simple algorithm and establish cut-points identifying survivors' cardiovascular fitness health-risk zones. We recruited 262 childhood cancer survivors (8-18 years old, ≥1-year posttreatment). Participants completed gold-standard cardiorespiratory fitness assessment (Cardiopulmonary Exercise Test [CPET; VO2max ]) and 6-minute walk test (6MWT). Associations with VO2max were included in a linear regression algorithm to predict VO2max , which was then cross-validated. We used Bland-Altman's limits of agreement and Receiver Operating Characteristic curves using FITNESSGRAM's "Healthy Fitness Zones" to identify cut-points for adequate cardiorespiratory fitness. A total of 199 participants (aged 13.7 ± 2.7 years, 8.5 ± 3.5 years posttreatment) were included. We found a strong positive correlation between VO2max and 6MWT distance (r = 0.61, r2 = 0.37, p < 0.001). Our regression algorithm included 6MWT distance, waist-to-height ratio, age and sex to predict VO2max (r = 0.79, r2 = 0.62, p < 0.001). Forty percentages of predicted VO2max values were within ±3 ml/kg/min of measured VO2max . The cut-point for FITNESSGRAM's "health-risk" fitness zone was 39.8 ml/kg/min (males: AUC = 0.88), and 33.5 ml/kg/min (females: AUC = 0.82). We present an algorithm to reasonably predict cardiorespiratory fitness for childhood cancer survivors, using inexpensive measures. This algorithm has useful clinical application, particularly when CPET is unavailable. Our algorithm has the potential to assist clinicians to identify survivors below the cut-points with increased cardiovascular disease-risk, to monitor and refer for tailored interventions with exercise specialists.

Barriers and enablers to physical activity and aerobic fitness deficits among childhood cancer survivors

BACKGROUND

Physical activity and aerobic fitness are modifiable risk factors for cardiovascular disease (CVD) after childhood cancer. How survivors engage in physical activity remains unclear, potentially increasing CVD risk. We assessed survivors' physical activity levels, barriers and enablers, fitness, and identified predictors of fitness and physical activity stage of change.

METHODS

Childhood cancer survivors (CCS; 8-18 years old) ≥1 year post-treatment were assessed for aerobic fitness (6-min walk test), used to extrapolate VO_2max , and body composition (InBody 570). Survivors self-reported physical activity to determine stage of change (Patient-Centered Assessment and Counselling for Exercise). Physical activity and fitness were compared with guidelines and CVD-risk cut-points (VO_2max  < 42 mL/kg/min: males; VO_2max  < 35 mL/kg/min: females). Multiple regression and mediator-moderator analysis were used to identify fitness predictors and stage of change.

RESULTS

One hundred two survivors (12.8 ± 3.3 years) participated (46% acute lymphoblastic leukaemia). Forty percent of males (VO_2max  = 43.3 ± 6.3 mL/kg/min) and 28% of females (VO_2max  = 36.5 ± 5.9 mL/kg/min) were in the CVD-risk category, while 25% met physical activity guidelines. Most prevalent physical activity barriers were fatigue (52%), preferring television instead of exercise (38%), and lacking time (34%). Predictive factors for reduced fitness included being older, female, higher waist-to-height ratio, higher screen time, and moderated by lower physical activity (r²  = 0.91, P < .001). Survivors with higher physical activity stage of change were male, lower body fat percentage, lower screen time, and lived with both parents (r = 0.42, P = .003).

CONCLUSION

Aerobic fitness and physical activity of CCS is low compared with population norms, potentially increasing CVD risk. Addressing physical activity barriers and enablers, including reducing screen time, could promote regular physical activity, reducing CVD risk.

The Utility of Cardiac Reserve for the Early Detection of Cancer Treatment-Related Cardiac Dysfunction: A Comprehensive Overview

With progressive advancements in cancer detection and treatment, cancer-specific survival has improved dramatically over the past decades. Consequently, long-term health outcomes are increasingly defined by comorbidities such as cardiovascular disease. Importantly, a number of well-established and emerging cancer treatments have been associated with varying degrees of cardiovascular injury that may not emerge until years following the completion of cancer treatment. Of particular concern is the development of cancer treatment related cardiac dysfunction (CTRCD) which is associated with an increased risk of heart failure and high risk of morbidity and mortality. Early detection of CTRCD appears critical for preventing long-term cardiovascular morbidity in cancer survivors. However, current clinical standards for the identification of CTRCD rely on assessments of cardiac function in the resting state. This provides incomplete information about the heart's reserve capacity and may reduce the sensitivity for detecting sub-clinical myocardial injury. Advances in non-invasive imaging techniques have enabled cardiac function to be quantified during exercise thereby providing a novel means of identifying early cardiac dysfunction that has proved useful in several cardiovascular pathologies. The purpose of this narrative review is (1) to discuss the different non-invasive imaging techniques that can be used for quantifying different aspects of cardiac reserve; (2) discuss the findings from studies of cancer patients that have measured cardiac reserve as a marker of CTRCD; and (3) highlight the future directions important knowledge gaps that need to be addressed for cardiac reserve to be effectively integrated into routine monitoring for cancer patients exposed to cardiotoxic therapies.

Cardio-Oncology Rehabilitation to Manage Cardiovascular Outcomes in Cancer Patients and Survivors: A Scientific Statement From the American Heart Association

Cardiovascular disease is a competing cause of death in patients with cancer with early-stage disease. This elevated cardiovascular disease risk is thought to derive from both the direct effects of cancer therapies and the accumulation of risk factors such as hypertension, weight gain, cigarette smoking, and loss of cardiorespiratory fitness. Effective and viable strategies are needed to mitigate cardiovascular disease risk in this population; a multimodal model such as cardiac rehabilitation may be a potential solution. This statement from the American Heart Association provides an overview of the existing knowledge and rationale for the use of cardiac rehabilitation to provide structured exercise and ancillary services to cancer patients and survivors. This document introduces the concept of cardio-oncology rehabilitation, which includes identification of patients with cancer at high risk for cardiac dysfunction and a description of the cardiac rehabilitation infrastructure needed to address the unique exposures and complications related to cancer care. In this statement, we also discuss the need for future research to fully implement a multimodal model of cardiac rehabilitation for patients with cancer and to determine whether reimbursement of these services is clinically warranted.

Subclinical Cardiac Dysfunction in Childhood Cancer Survivors on 10-Years Follow-Up Correlates With Cumulative Anthracycline Dose and Is Best Detected by Cardiopulmonary Exercise Testing, Circulating Serum Biomarker, Speckle Tracking Echocardiography, and Tissue Doppler Imaging

Background: Survivors of childhood cancer are at risk for anthracycline- and/or radiotherapy-induced cardiotoxicity. Aims: The aim of this study was to assess clinical, laboratory, and imaging parameters of subclinical cardiovascular disease in childhood cancer survivors. Methods: Patients underwent cardiopulmonary exercise test (CPET), laboratory testing, transthoracic echocardiography (TTE) with tissue doppler imaging (TDI) and speckle tracking. A subset of patients also underwent cardiovascular magnetic resonance imaging (CMR). Findings were correlated to cumulative anthracycline and exposure to mediastinal irradiation during cancer treatment. In a subgroup analysis, TTE and CMR findings were compared to data from 40 gender- and age-matched patients with childhood onset hypertrophic cardiomyopathy (HCM). Results: Cardiac evaluation was performed in 79 patients (43 males) at 11.2 ± 4.5 years after cancer treatment. Oncologic diagnosis at a median age of 12.0 years was Hodgkin lymphoma in 20, sarcoma in 17, acute leukemia in 24, relapse leukemia in 10, and others in 8 patients. Cumulative anthracycline dose exceeded 300 mg/m² in 28 patients. Twenty six patients also received mediastinal irradiation. Decreased peak respiratory oxygen uptake in % predicted on CPET, increased levels of N-terminal pro-brain natriuretic peptide (NTproBNP), increased global longitudinal strain on TTE speckle tracking, and diastolic dysfunction on TDI were the most prominent findings on detailed cardiology follow-up. In contrast to HCM patients, childhood cancer survivors did not show left ventricular hypertrophy (LVPWd z-score median 0.9 vs. 2.8, p < 0.001), hyperdynamic systolic function on TTE (Ejection fraction 62 ± 7 vs. 72 ± 12%, p = 0.001), or fibrotic myocardial changes on CMR (Late gadolinium positive 0/13 vs. 13/36, p = 0.001; extracellular volume fraction 22 ± 2 vs. 28 ± 3, p < 0.001) at time of follow-up. There was no correlation between chest radiation exposure and abnormal cardiac findings. Cumulative anthracycline dose was the only significant independent predictor on multivariate analysis for any cardiovascular abnormality on follow-up (p = 0.036). Conclusion: Increasing cumulative anthracycline dose during cancer treatment correlates with subclinical cardiac dysfunction in childhood cancer survivors best detected by elevated cardiac serum biomarkers, decreased exercise capacity on CPET, and abnormalities on echocardiographic speckle tracking and TDI.

Exercise Intolerance, Mortality, and Organ System Impairment in Adult Survivors of Childhood Cancer

PURPOSE

Exercise intolerance, associated with heart failure and death in general populations, is not well studied in survivors of childhood cancer. We examined prevalence of exercise intolerance in survivors exposed or not to cardiotoxic therapy, and associations among organ system function, exercise intolerance, and mortality.

METHODS

Participants consisted of 1,041 people who had survived cancer ≥ 10 years (and had or did not have exposure to anthracyclines and/or chest-directed radiation) and 285 control subjects. Exercise intolerance was defined as peak oxygen uptake < 85% predicted from maximal cardiopulmonary exercise testing; organ functions were ascertained with imaging or clinical testing. Multivariable regression of the data was performed to compare exercise capacity between survivors exposed or unexposed to cardiotoxic therapy and control subjects, and to evaluate associations between treatment and organ function, and organ function and exercise intolerance. Propensity score methods in time-to-event analyses evaluated associations between exercise intolerance and mortality.

RESULTS

Survivors (mean age ± standard deviation [SD], 35.6 ± 8.8 years) had lower mean (± SD) peak oxygen uptake (exposed: 25.74 ± 8.36 mL/kg/min; unexposed: 26.82 ± 8.36 mL/kg/min) than did control subjects (32.69 ± 7.75 mL/kg/min; P for all < .001). Exercise intolerance was present in 63.8% (95% CI, 62.0% to 65.8%) of exposed survivors, 55.7% (95% CI, 53.2% to 58.2%) of unexposed survivors, and 26.3% (95% CI, 24.0% to 28.3%) of control subjects, and was associated with mortality (hazard ratio, 3.9; 95% CI, 1.09 to 14.14). Global longitudinal strain (odds ratio [OR], 1.71; 95% CI, 1.11 to 2.63), chronotropic incompetence (OR, 3.58; 95% CI, 1.75 to 7.31); forced expiratory volume in 1 second < 80% (OR, 2.59; 95% CI, 1.65 to 4.09), and 1 SD decrease in quadriceps strength (OR, 1.49; 95% CI, 1.23 to 1.82) were associated with exercise intolerance. Ejection fraction < 53% was not associated with exercise intolerance.

CONCLUSION

Exercise intolerance is prevalent among childhood cancer survivors and associated with all-cause mortality. Treatment-related cardiac (detected by global longitudinal strain), autonomic, pulmonary, and muscular impairments increased risk. Survivors with impairments may require referral to trained specialists to learn to accommodate specific deficits when engaging in exercise.

Early markers of cardiovascular injury in childhood leukaemia survivors treated with anthracycline chemotherapy

BACKGROUND

Cardiovascular disease (CVD) is the leading non-malignant cause of death in childhood cancer survivors. Heightened risk of CVD is often attributable to treatment with anthracycline chemotherapy. Anthracycline-mediated cardiac injury may lie latent for years following cessation of treatment and is therefore often not detected until disease is advanced and aggressive therapy is required. Symptomatic CVD may be preceded by subclinical cardiac and vascular dysfunction. This study aimed to determine whether such dysfunction could be detected in healthy, anthracycline-treated survivors of childhood leukaemia.

METHODS

Cardiac magnetic resonance imaging (cMRI) with late gadolinium enhancement and endothelial function were used to characterise pre-clinical stages of CVD. Twenty-two long-term (>5 years survival; age 21 ± 3 years) childhood leukaemia survivors were assessed. All survivors were asymptomatic and had normal resting echocardiography. To exclude potential confounding effects of radiotherapy, no survivors had received this treatment. Twenty-two similarly aged (25 ± 3 years) gender-matched controls were recruited for comparison.

RESULTS

Left ventricular ejection fraction was lower in the survivors (55.0 ± 4.6%) compared to the controls (59.4 ± 6.2%; p = 0.010). Further, five survivors (23%) had clinically reduced (<50%) left ventricular ejection fraction. Normalised left ventricular end systolic volume was augmented in survivors (40.0 ± 9.1 mL·m2 vs. 34.5 ± 7.5 mL·m2; p = 0.038). Cardiac MRI did not show any late gadolinium enhancement. High resolution, ultrasound-derived flow mediated dilation was impaired in survivors (6.7 ± 2.1% vs. 8.60 ± 1.91%, p = 0.005).

CONCLUSIONS

We detected subclinical changes in cardiovascular structure and function indicative of early disease in anthracycline-treated childhood leukaemia survivors with normal echocardiography. Early detection and characterisation of underlying disease allows for timely intervention and improved outcomes in this at-risk population.

Is health status impaired in childhood cancer survivors? A systematic review and meta-analysis

BACKGROUND

An increase in survival rates of childhood cancer is associated with long-term health issues in survivors.

METHODS

We conducted a systematic review and meta-analysis comparing health status-related endpoints in childhood cancer survivors (CCS) versus controls.

RESULTS

Eighty-six studies (n = 98,480 participants, 62% CCS) were included in the review. Of these, 73 studies (n = 96,550, 63% CCS) could be meta-analyzed. CCS showed a lower left ventricular ejection and fractional shortening (SMD=-0.59 and -0.55, respectively, both p < 0.01 [n=1,824 and 1,880]), a lower HDL-cholesterol concentration (SMD=-0.48, p<0.001, n=1,378) and a higher waist-to-hip ratio (SMD=0.61, p < 0.01, n=229) than their healthy peers. No significant differences were found for the remaining endpoints.

CONCLUSIONS

CCS is associated with a lower left ventricular function and HDL-cholesterol level, and a higher waist-to-hip ratio than healthy controls. These findings support the need to closely monitor the cardiometabolic health status of CCS and to implement preventive lifestyle interventions for this population.

Plethysmographic and biochemical markers in the diagnosis of endothelial dysfunction in pediatric acute lymphoblastic leukemia survivors - new applications

Acute lymphoblastic leukemia (ALL) and its treatment are associated with endothelial dysfunction (ED) and increased cardiovascular risk in adulthood. There are no data on ED in children after successful treatment of ALL. We aimed to assess new ED in these children using the plethysmographic reactive hyperemia index (RHI) and biomarkers that are known to be related to ED. In all, 22 children (mean 15.6 years), after successful treatment of ALL, and 18 healthy subjects were included in this prospective study. RHI, plasma concentrations of asymmetric dimethyl arginine (ADMA), high-sensitive CRP (hsCRP) and E-selectin were measured in all children. RHI values were significantly lower in ALL patients when compared with healthy controls (p<0.05). hsCRP was significantly increased in ALL patients compared with the control group (p<0.001). E-selectin plasma levels were higher in ALL patients as compared to healthy controls (p=0.05). This is the first study that combines both plethysmographic and biochemical methods to assess ED in ALL survivors. Significantly decreased RHI with elevated plasma concentrations of biochemical markers imply a possible association with premature ED in ALL patients. The combined diagnostic approach seems to be a valuable tool for more accurate detection of ED and preventive cardiovascular management in these patients.

Cardiopulmonary Aerobic Fitness Assessment During Maximal and Submaximal Exercise Testing in Pediatric Oncology Patients After Chemotherapy

PURPOSE

The cardiopulmonary exercise test (CPET) is a valuable tool to assess cardiopulmonary exercise capacity in pediatric oncology patients after chemotherapy. In addition, few studies on the utility of submaximal testing have been performed, which could be important as some patients are unable to complete a maximal effort test secondary to deconditioning by both disease and treatment.

MATERIALS AND METHODS

We performed a retrospective chart review of pediatric cancer patients exposed to chemotherapy from 1992 to 2013 who underwent CPET with cycle ergometry (n=27). The study patients were compared with age-matched, sex-matched, and size-matched normal controls. The submaximal measure recorded was the oxygen consumption (VO2)@respiratory exchange ratio (RER) 1.0 during a maximal effort test.

RESULTS

The chemotherapy group demonstrated significantly lower exercise time (9.2±3.6 vs. 11.4±3.8; P=0.008), total work capacity (4914.4±3290.3 vs. 7664.4±4289.5; P=0.004), systolic blood pressure at peak exercise (162.9±23.2 vs. 177.3±23.8; P=0.01), indexed peak VO2 (33.9±6.9 vs. 40.0±6.3; P=0.001), and indexed peak oxygen pulse (6.1±1.3 vs. 7.0±1.5; P=0.004)). For the submaximal outcome measured, 11/27 of the chemotherapy patients had VO2@RER 1.0 values <-2 SD from the mean compared with 0/27 control patients.

CONCLUSIONS

Pediatric patients exposed to chemotherapy have impaired cardiopulmonary exercise capacity. The VO2@RER 1.0 in chemotherapy patients suggests that this may be a reliable submaximal measure in this population.

IMPLICATIONS FOR CANCER SURVIVORS

This study demonstrates that the CPET can be used in pediatric cancer survivors with prior exposure to chemotherapy to demonstrate impaired cardiopulmonary exercise tolerance, which is demonstrated on submaximal and maximal effort testing.

Dynamic Myocardial Response to Exercise in Childhood Cancer Survivors Treated with Anthracyclines

BACKGROUND

Anthracycline cardiotoxicity can cause significant long-term morbidity in childhood cancer survivors (CCS), but many CCS do not manifest clinical symptoms until adulthood. The aims of this study were to characterize the dynamic myocardial response to exercise of CCS at long-term follow-up by combining semisupine bicycle exercise stress echocardiography with myocardial imaging techniques and to establish whether semisupine bicycle exercise stress echocardiography could identify CCS with abnormal exercise response.

METHODS

This was a single-center prospective cross-sectional study. One hundred CCS and 51 control subjects underwent semisupine bicycle exercise stress echocardiography. Color Doppler tissue imaging peak systolic (s') and diastolic (e') velocities, myocardial acceleration during isovolumic contraction, and longitudinal strain were measured at rest and at incremental heart rates in the left ventricular (LV) lateral wall, basal septum, and right ventricle. The relationship with increasing heart rate was evaluated for each parameter by plotting the values against heart rate at each stage of exercise. Kernel density estimate was used to establish the normality of the individual CCS exercise responses.

RESULTS

At rest, no significant differences were found for LV lateral wall, right ventricular (RV), and basal septal systolic and diastolic velocities between CCS and control subjects. Only septal e' was lower in CCS. LV longitudinal strain was similar between groups, while RV longitudinal strain was lower in CCS. At peak exercise, LV lateral wall, RV, and septal s' were not different between groups, while e' were significantly lower in CCS. LV lateral wall and septal isovolumic acceleration were also reduced in CCS. LV longitudinal strain was different between groups, while RV longitudinal strain was similar. The dynamic response of Doppler tissue imaging velocities, isovolumic acceleration, and strain was similar between CCS and control subjects. Kernel density estimate analysis confirmed that most CCS responses were within the normal range.

CONCLUSIONS

At 10-year follow-up, anthracycline-treated CCS with normal baseline ejection fractions have LV and RV systolic and diastolic myocardial exercise response comparable with that of control subjects. Minor differences were observed between CCS and control subjects at rest and at peak exercise, but the dynamic response is within the normal range.

Cardiotoxicity from anthracycline and cardioprotection in paediatric cancer patients

Notwithstanding the steady progress in survival rates of children and adolescents suffering from cancer, the benefits associated with chemotherapy do not come without risks involving multiple organs and systems, including the cardiovascular apparatus. Anthracyclines-often administered in combination with radiation therapy and/or surgery-are the most used chemotherapeutic compounds in order to treat tumours and blood malignancies even in paediatric age. Being an important side-effect of anthracyclines, carduitoxicity may limit their efficacy during the treatment and induce long-term sequelae, observed even many years after therapy completion. The purpose of this review was to perform an overview about all the possible strategies to prevent and/or limit the anthracyclines adverse side-effects for the cardiovascular system in childhood cancer survivors.

Aerobic exercise in anthracycline-induced cardiotoxicity: a systematic review of current evidence and future directions

Cancer and cardiovascular disease are major causes of morbidity and mortality worldwide. Older cancer patients often wrestle with underlying heart disease during cancer therapy, whereas childhood cancer survivors are living long enough to face long-term unintended cardiac consequences of cancer therapies, including anthracyclines. Although effective and widely used, particularly in the pediatric population, anthracycline-related side effects including dose-dependent association with cardiac dysfunction limit their usage. Currently, there is only one United States Food and Drug Administration-approved drug, dexrazoxane, available for the prevention and mitigation of cardiotoxicity related to anthracycline therapy. While aerobic exercise has been shown to reduce cardiovascular complications in multiple diseases, its role as a therapeutic approach to mitigate cardiovascular consequences of cancer therapy is in its infancy. This systematic review aims to summarize how aerobic exercise can help to alleviate unintended cardiotoxic side effects and identify gaps in need of further research. While published work supports the benefits of aerobic exercise, additional clinical investigations are warranted to determine the effects of different exercise modalities, timing, and duration to identify optimal aerobic training regimens for reducing cardiovascular complications, particularly late cardiac effects, in cancer survivors exposed to anthracyclines.

Impaired Left Ventricular Reserve in Childhood Cancer Survivors Treated With Anthracycline Therapy

BACKGROUND

Childhood cancer survivors show evidence of diffuse myocardial fibrosis that is related to exercise capacity. The mechanism of reduced exercise tolerance in anthracycline cardiotoxicity remains unclear. We explored the determinants of exercise intolerance by evaluating left ventricular (LV) distensibility and functional reserve.

METHODS

Patients (n = 22) and healthy controls (n = 10) underwent two-dimensional echocardiography while supine, upright, and during cycle exercise. LV distensibility was measured as the change in end-diastolic cavity area (EDCA) from supine to the upright position. LV functional reserve was assessed during peak exercise, and measured as the exercise-induced change in systolic circumferential strain rate (SR) and early-diastolic SR (EDSR). The peak rate of oxygen consumption was measured by indirect calorimetry.

RESULTS

Median age of patients was 16 years (range 8-19) and controls 14 years (range 8-19). Median time since anthracycline therapy was 6 years (range 2-16). Peak oxygen consumption was significantly lower in patients compared to controls (35 ml/kg/min [28-60] vs. 45 ml/kg/min [44-53], P = 0.005). Transitioning from the supine position to the upright position caused a similar reduction in LV EDCA, suggesting similar LV distensibility between patients (-22% [-46 to -4]) and controls (-20% [-46 to -3], P = 0.3). However, during exercise, both systolic SR and EDSR reserve were significantly impaired in patients (∆SR: 93% [14-308], ∆EDSR: -4.5% [-88 to 121]) compared to controls (∆SR: 128% [54-230], P = 0.046; ∆EDSR: 74% [22-234], P = 0.02).

CONCLUSIONS

Our findings suggest that impaired LV contractility and functional reserve play a role in the reduced exercise capacity in anthracycline cardiotoxicity rather than LV distensibility.

Impaired exercise capacity and left ventricular function in long-term adult survivors of childhood acute lymphoblastic leukemia

BACKGROUND

Survivors of childhood acute lymphoblastic leukemia (ALL) are at risk for late cardiotoxic effects of cancer treatment, but conflicting evidence exists on the effects of anthracyclines on left ventricular (LV) diastolic function and exercise capacity.

PROCEDURE

We performed a cross-sectional study with comprehensive echocardiography in 138 adult survivors of childhood ALL, median 23.4 years after diagnosis. Pulsed tissue Doppler measurements of early diastolic mitral annular velocities (e') were used for the assessment of diastolic function, and compared to 138 matched controls. Of the survivors, 133 also performed ergospirometry measuring peak oxygen uptake (VO2 max). Associations between cancer treatment, LV function, and VO2 max were analyzed.

RESULTS

The survivor group had lower e' values than controls (e' septal 11.0 vs. 12.6 cm/s, P < 0.001), but the difference was confined to the subgroup of anthracycline treated survivors (median cumulative dose 120 mg/m(2) ). Anthracycline exposure was inversely correlated with e' (regression coefficient -1.581, P=0.009). Reduced VO2 max/kg occurred in 47% of the survivors, but more often in anthracycline treated survivors (56%) than anthracycline naïve survivors (17%, P<0.001). Anthracycline exposure was inversely correlated with VO2 max/kg (regression coefficient -3.084, P = 0.05 in multivariate analysis). Furthermore, associations were observed between measures of LV function and VO2 max/kg, and e' was the best predictor of VO2 max/kg (standardized coefficient 0.355, P < 0.001 in multivariate analysis).

CONCLUSIONS

Adult survivors of childhood ALL have increased risk for impaired LV diastolic function and impaired exercise capacity, both associated with previous anthracycline exposure. Furthermore, there is an association between LV diastolic function and exercise capacity.

Endothelial health in childhood acute lymphoid leukemia survivors: pilot evaluation with peripheral artery tonometry

BACKGROUND

Childhood cancer survivors are a growing population at risk for poor cardiac outcomes. Acute lymphoid leukemia (ALL) survivors are among those at increased risk of cardiovascular complications. Early identification of impaired vascular health may allow for interventions to improve these outcomes. The purpose of this study was to evaluate vascular health using peripheral artery tonometry in ALL survivors and compare results with healthy siblings.

PROCEDURE

Sixteen ALL survivor, healthy sibling pairs, aged 8 to 20 years, were evaluated for vascular health and cardiovascular risk factors (body mass index, central adiposity, blood pressure, and fitness). One-tailed paired t test was used to compare the groups.

RESULTS

Survivors were similar to siblings in cardiovascular risk measures but had poorer vascular health as measured by reactive hyperemia index (survivor RHI 1.54 vs. sibling 1.77; P=0.0474).

CONCLUSION

This study reveals that even among survivors who are comparable to their healthy siblings in other traditional cardiovascular risks, there is evidence of poorer vascular health.

Assessing anthracycline-treated childhood cancer survivors with advanced stress echocardiography

BACKGROUND

Surveillance for anthracycline cardiotoxicity in cancer survivors typically utilizes resting M-mode and two-dimensional echocardiography, which are insensitive to detection of subtle myocardial changes. We examined childhood cancer survivors treated with anthracyclines during exercise using various echocardiography techniques to investigate if these tools can better detect subclinical cardiac dysfunction.

PROCEDURE

We recruited asymptomatic survivors at least five years post treatment. Echocardiography was performed at rest and at termination of exercise utilizing tissue Doppler techniques and strain rate imaging.

RESULTS

Eighty participants were characterized by cardiotoxicity risk status (high [12], moderate [23], low [24], no risk [21]) as defined by the Children's Oncology Group Long Term Follow-Up Guidelines v3.0. The high-risk group had a higher resting heart rate than controls (100 vs. 88 bpm [P for trend = 0.049]). Peak aerobic capacity in all groups was similar. Compared to controls at rest, the high-risk group had evidence of diastolic dysfunction with lower E/A ratios (1.4 vs. 2.0, P = 0.008) and higher septal early diastolic velocities (E/E') of 11.7 versus 9.9 (P = 0.165). With exercise, this difference resolved and myocardial contractile reserve was preserved.

CONCLUSIONS

Asymptomatic, pediatric cancer survivors at high-risk for anthracycline cardiotoxicity have some evidence of diastolic filling abnormalities at rest. With exercise, they augment their systolic and diastolic function to achieve normal maximal aerobic capacity suggesting they are able to compensate for mild cardiac dysfunction in the early years after exposure. Additionally, findings suggest that routine exercise echocardiography may not be a useful surveillance tool to assess anthracycline cardiotoxicity.

Recommendations for cardiomyopathy surveillance for survivors of childhood cancer: a report from the International Late Effects of Childhood Cancer Guideline Harmonization Group

Survivors of childhood cancer treated with anthracycline chemotherapy or chest radiation are at an increased risk of developing congestive heart failure. In this population, congestive heart failure is well recognised as a progressive disorder, with a variable period of asymptomatic cardiomyopathy that precedes signs and symptoms. As a result, several clinical practice guidelines have been developed independently to help with detection and treatment of asymptomatic cardiomyopathy. These guidelines differ with regards to definitions of at-risk populations, surveillance modality and frequency, and recommendations for interventions. Differences between these guidelines could hinder the effective implementation of these recommendations. We report on the results of an international collaboration to harmonise existing cardiomyopathy surveillance recommendations using an evidence-based approach that relied on standardised definitions for outcomes of interest and transparent presentation of the quality of the evidence. The resultant recommendations were graded according to the quality of the evidence and the potential benefit gained from early detection and intervention.

Subclinical cardiotoxicity in childhood cancer survivors exposed to very low dose anthracycline therapy

BACKGROUND

Subclinical cardiotoxicity occurs in childhood cancer survivors following moderate and high anthracycline doses. However, less is known about the subclinical changes in left ventricular (LV) structure that occur after very low anthracycline doses of ≤ 100 mg/m(2). This study was designed to assess LV function and key structural parameters following very low doses of anthracycline.

PROCEDURE

Conventional 2-dimensional echocardiograms with Doppler were obtained in 91 survivors of childhood cancer exposed to ≤ 100 mg/m(2), an average of 9.8 years from diagnosis. LV structural measurements were converted into Z-scores. The Z-score distributions were compared to those of the normal population. Diastolic and systolic function were quantified.

RESULTS

The cohort demonstrated a decreased posterior wall thickness (mean Z-score -1.01) and mildly decreased LV end diastolic (mean Z-score -0.85) and systolic (mean Z-score -0.84) dimensions compared to the normal population (P < 0.001). Further, 28% of patients (n = 25) had abnormal LV posterior wall thickness, ≥ 2 standard deviations below the mean (Z-score ≤ -2). There were no patients with diastolic dysfunction or symptomatic systolic dysfunction, however four patients demonstrated abnormal SF ≤ 28%.

CONCLUSIONS

A significant proportion of patients exposed to very low doses of anthracycline demonstrate subclinical abnormalities in LV structure, despite the absence of radiation or other risk factors. While we cannot say whether these structural changes will result in clinically significant cardiac disease, the reported progressive nature of these findings raises concern that there may truly be no safe dose of anthracycline.

Diffuse myocardial fibrosis by T1-mapping in children with subclinical anthracycline cardiotoxicity: relationship to exercise capacity, cumulative dose and remodeling

BACKGROUND

The late cardiotoxic effects of anthracycline chemotherapy influence morbidity and mortality in the growing population of childhood cancer survivors. Even with lower anthracycline doses, evidence of adverse cardiac remodeling and reduced exercise capacity exist. We aim to examine the relationship between cardiac structure, function and cardiovascular magnetic resonance (CMR) tissue characteristics with chemotherapy dose and exercise capacity in childhood cancer survivors.

METHODS

Thirty patients (15 ± 3 years), at least 2 years following anthracycline treatment, underwent CMR, echocardiography, and cardiopulmonary exercise testing (peak VO(2)). CMR measured ventricular function, mass, T(1) and T(2) values, and myocardial extracellular volume fraction, ECV, a measure of diffuse fibrosis based on changes in myocardial T1 values pre- and post-gadolinium. Cardiac function was also assessed with conventional and speckle tracking echocardiography.

RESULTS

Patients had normal LVEF (59 ± 7%) but peak VO(2) was 17% lower than age-predicted normal values and were correlated with anthracycline dose (r = -0.49). Increased ECV correlated with decreased mass/volume ratio (r = -0.64), decreased LV wall thickness/height ratio (r = -0.72), lower peak VO(2)(r = -0.52), and higher cumulative dose (r = 0.40). Echocardiographic measures of systolic and diastolic function were reduced compared to normal values (p < 0.01), but had no relation to ECV, peak VO(2) or cumulative dose.

CONCLUSIONS

Myocardial T1 and ECV were found to be early tissue markers of ventricular remodeling that may represent diffuse fibrosis in children with normal ejection fraction post anthracycline therapy, and are related to cumulative dose, exercise capacity and myocardial wall thinning.

Asymptomatic cardiac toxicity in long-term cancer survivors: defining the population and recommendations for surveillance

Advances in the treatment of pediatric and adult cancer have reduced the mortality rates from these disorders and have led to an ever-increasing population of long-term survivors. Chemotherapy and radiotherapy may cause premature cardiac disease that may be asymptomatic or symptomatic. All patients exposed to chemotherapy with cardiotoxic potential or chest radiotherapy have stage A heart failure and the goal of surveillance and treatment is to prevent progression to stages B-D. Screening strategies, including the use of biomarkers, echocardiography, and expert opinion surveillance and treatment recommendations, are presented.

Ventricular systolic reserve in asymptomatic children previously treated with low doses of anthracyclines: a longitudinal, prospective exercise echocardiography study

BACKGROUND

The time course of mild cardiotoxicity induced by anthracycline remains unknown. The aim of this study was to evaluate the long-term evolution of decreased myocardial reserve in children previously treated with a cumulative dose of anthracycline up to 100 mg/m(2).

PATIENTS AND METHODS

Twenty-seven asymptomatic cancer survival patients (25 with lymphoblastic leukemia), in continuous remission and off treatment for >12 months with no alterations in conventional echocardiograms were evaluated by exercise echocardiography at 37 ± 15.4 months (T1) and 101 ± 24 months (T2) after finishing treatment (ADRIA group). This group was compared with 25 healthy individuals (control group) similar to the ADRIA group with respect to age and body surface area (BSA). All individuals underwent treadmill exercise testing according to Bruce protocol. Echocardiograms were performed before and immediately after exercise.

RESULTS

The groups were similar regarding cardiac structure and left ventricular (LV) systolic function at rest at T1 and T2. The growth of LV posterior wall thickness related to BSA was lower in the ADRIA group at T2. Post exercise, smaller LV ejection indexes and attenuated changes in the afterload in ADRIA group were observed at T1 and T2.

CONCLUSION

The decreased systolic reserve induced by a low dose of anthracycline in asymptomatic children and adolescents remains unaffected over a 5-year period, suggesting that positive outcomes in chronic cardiotoxicity would be expected in patients with mild impairment after anthracycline treatment.

Cardiotoxicity of childhood cancer treatment: update and current knowledge on long-term follow-up

Therapeutic advances in paediatric oncology allowed increasing numbers of children to survive until adulthood. However, chemotherapy and radiotherapy are potentially cardiotoxic and contribute to a significant morbidity and mortality, cardiovascular events remaining the leading cause of death among survivors. This review summarizes the physiopathology of treatment-related cardiovascular diseases, their incidence, and the risk factors associated with each specific therapy. Few studies have investigated the cardiac outcomes of adult surviving from childhood cancers but all demonstrated a substantial risk for late cardiac effects. Cardiovascular monitoring, prevention, and early detection of cardiac dysfunction are, therefore, the keystones of an improved long-term outcome.

Exercise training mitigates anthracycline-induced chronic cardiotoxicity in a juvenile rat model

BACKGROUND

Childhood cancer survivors are at greater risk of cardiovascular complications once they reach adulthood. Anthracyclines may be a major contributor to these delayed-onset complications, yet their use continues because of favorable clinical outcomes. Exercise has been shown to protect against anthracycline cardiotoxicity, yet it is unclear whether exercise can protect against delayed-onset cardiotoxicity when treatment is initiated in childhood. The aim of the present study was to determine if exercise training provides cardioprotection in a juvenile rat model of delayed-onset anthracycline cardiotoxicity.

PROCEDURE

At 25 days of age, male Sprague-Dawley rat pups were subjected to a treatment regimen with the anthracycline doxorubicin (DOX). Pups received DOX at 2 mg/kg on 7 consecutive days (cumulative dose 14 mg/kg) or saline as a control. At the time DOX treatment began, pups remained sedentary or were allowed to voluntarily exercise. Ten weeks after the initiation of exercise, cardiac function was assessed both in vivo and ex vivo.

RESULTS

DOX treatment stunted normal growth and significantly impaired cardiac function. While voluntary exercise did not offset changes in the growth curve, it did provide significant cardioprotection against DOX-induced cardiotoxicity.

CONCLUSIONS

Exercise training, initiated at the time treatment begins, can protect against delayed-onset anthracycline-induced cardiotoxicity in adult rats that were treated with anthracyclines as juveniles.

Review of cardiotoxicity in pediatric cancer patients: during and after therapy

With the improvement in survival from childhood cancer, late effects of therapy are becoming more apparent. Cardiac disease, one of these late effects, has a significant impact on the life of survivors of childhood cancers. Most survivors are followed by primary care doctors and adult subspecialists after they have graduated from pediatric centers. Since much of the cardiac toxicity of therapy occurs years off of therapy, it is important for these physicians to be aware of how to monitor survivors for the development of cardiac toxicities. In this paper we will discuss the incidence of cardiac disease during treatment and in survivors, what treatment modalities contribute to its development and modalities utilized to screen for cardiac disease. Recommendations for posttherapy monitoring will be emphasized.