Peak oxygen uptake correlates with survival without clinical deterioration in ambulatory children with dilated cardiomyopathy

Serial Exercise Testing in Children With Known or Suspected Congenital and Acquired Heart Disease: A Narrative Review and Survey of Current Practice

BACKGROUND

Exercise parameters can be altered in children with congenital heart disease or acquired heart disease compared with children with normal hearts. Exercise testing has proven a useful tool to predict patient outcomes and even the need for reintervention in several cardiovascular disease processes. There are established guidelines for serial exercise stress testing in adults with congenital heart disease, but corollary guidelines do not exist for the pediatric population.

METHODS AND RESULTS

A narrative literature review was completed. Evidence was ranked by a 4-point scale as outlined by the American College of Sports Medicine evidence categories. A survey was sent to experts in pediatric exercise physiology across the country regarding their current testing practices for 26 unique congenital heart disease or known or suspected acquired heart disease lesions. Survey questions were related to the frequency of testing, the age at which exercise testing is started, and if the frequency of testing is altered by a patient presenting with symptoms. Our literature search yielded 122 relevant studies pertaining to exercise stress testing in pediatric heart disease. We received 59 responses to our survey from 33 unique institutions in the United States and Canada.

CONCLUSIONS

Twenty-one summaries were provided regarding exercise stress testing in pediatric patients with heart disease. Multicentered or national stress testing registries may allow for adequate sample sizes of rare pediatric diseases to allow for development of improved guidelines regarding the type and timing of stress testing.

Brazilian Guideline for Exercise Testing in Children and Adolescents - 2024

CLASSES OF RECOMMENDATION

LEVELS OF EVIDENCE

Insights from Cardiopulmonary Exercise Testing in Pediatric Patients with Hypertrophic Cardiomyopathy

The usefulness of cardiopulmonary exercise test (CPET) in adult hypertrophic cardiomyopathy (HCM) patients is well-known, whereas its role in pediatric HCM patients has not yet been explored. The present study investigates possible insights from a CPET assessment in a cohort of pediatric HCM outpatients in terms of functional and prognostic assessment. Sixty consecutive pediatric HCM outpatients aged <18 years old were enrolled, each of them undergoing a full clinical assessment including a CPET; a group of 60 healthy subjects served as controls. A unique composite end-point of heart failure (HF) related and sudden cardiac death (SCD) or SCD-equivalent events was also explored. During a median follow-up of 53 months (25th–75th: 13–84 months), a total of 13 HF- and 7 SCD-related first events were collected. Compared to controls, HCM patients showed an impaired functional capacity with most of them showing peak oxygen uptake (pVO₂) values of <80% of the predicted, clearly discrepant with functional New York Heart Association class assessment. The composite end-point occurred more frequently in patients with the worst CPETs’ profiles. At the univariate analysis, pVO₂% was the variable with the strongest association with adverse events at follow-up (C-index = 0.72, p = 0.025) and a cut-off value equal to 60% was the most accurate in identifying those patients at the highest risk. In a pediatric HCM subset, the CPET assessment allows a true functional capacity estimation and it might be helpful in identifying early those patients at high risk of events.

Potential for and timing of recovery in children with dilated cardiomyopathy

OBJECTIVE

Understanding the clinical course and time-frame for recovery is helpful to guide management and counselling following a diagnosis of Dilated Cardiomyopathy (DCM). We aimed to document outcomes and time to recovery for a cohort of patients with a dilated cardiomyopathy phenotype.

METHODS

An observational cohort methodology was used to collect retrospective data from the departmental database for those identified with DCM. Data relating to mode of presentation, echocardiographic parameters, clinical management and outcome were collated and analysed. Predictors and time-scale for recovery were investigated and reported.

RESULTS

209 new referrals were included within the time frame. 82 children median age 1.0years (IQR 3.4) required intensive care (ICU) and their survival without death or transplant was 51% to one year and 45% to five years. 127 children presented to the pediatric heart failure clinic. Excluding 58 with neuromuscular disease, median age was 4.1years (IQR 11.3) & survival without death or transplant 85% to 1year and 50% to 5years. NT-proBNP normalized in survivors before echocardiographic parameters. Predictors of recovery included younger age, female sex and smaller left ventricular end diastolic Z score on echocardiogram at presentation.

CONCLUSION

Transplant-free survival to one year is significantly better for patients presenting to clinic, but longer-term survival is better amongst those presenting to ICU due to a late attrition in those with less severe heart failure at presentation. Falling NT-proBNP is the earliest marker of recovery. Recovery of cardiac function remains possible up to three years from presentation.

Six-Minute Walk Test as a Predictor for Outcome in Children with Dilated Cardiomyopathy and Chronic Stable Heart Failure

Cardiopulmonary exercise testing is an important tool to predict prognosis in children and adults with heart failure. A much less sophisticated exercise test is the 6 min walk test, which has been shown an independent predictor for morbidity and mortality in adults with heart failure. Therefore, we hypothesized that the 6 min walk test could be predictive for outcome in children with dilated cardiomyopathy. We prospectively included 49 children with dilated cardiomyopathy ≥6 years who performed a 6 min walk test. Median age was 11.9 years (interquartile range [IQR] 7.4-15.1), median time after diagnosis was 3.6 years (IQR 0.6-7.4). The 6 min walk distance was transformed to a percentage of predicted, using age- and gender-specific norm values (6MWD%). For all patients, mean 6MWD% was 70 ± 21%. Median follow-up was 33 months (IQR 14-50). Ten patients reached the combined endpoint of death or heart transplantation. Using univariable Cox regression, a higher 6MWD% resulted in a lower risk of death or transplantation (hazard ratio 0.95 per percentage increase, p = 0.006). A receiver operating characteristic curve was generated to define the optimal threshold to identify patients at highest risk for an endpoint. Patients with a 6MWD% < 63% had a 2 year transplant-free survival of 73%, in contrast to a transplant-free survival of 92% in patients with a 6MWD% ≥ 63% (p = 0.003). In children with dilated cardiomyopathy, the 6 min walk test is a simple and feasible tool to identify children with a higher risk of death or heart transplantation.

Feasibility and safety of cardiopulmonary exercise testing in children with pulmonary hypertension

BACKGROUND

Cardiopulmonary exercise testing helps prognosticate and guide treatment in adults with pulmonary hypertension. Concerns regarding its feasibility and safety limit its use in children with pulmonary hypertension. We aimed to assess the feasibility and safety of cardiopulmonary exercise testing in a large paediatric pulmonary hypertension cohort.

METHODS

We reviewed all consecutive cardiopulmonary exercise tests performed between March, 2004 and November, 2013. The exclusion criteria were as follows: height <120 cm, World Health Organization class IV, history of exercise-induced syncope, or significant ischaemia/arrhythmias. Significant events recorded were as follows: patient-reported symptoms, arrhythmias, electrocardiogram abnormalities, and abnormal responses of arterial O2 saturation.

RESULTS

A total of 98 children underwent 167 cardiopulmonary exercise tests. The median age was 14 years (inter-quartile range 10-15 years). Peak oxygen uptake was 20.4±7.3 ml/kg/minute, corresponding to 51.8±18.3% of the predicted value. Peak respiratory quotient was 1.08±0.16. All the tests except two were maximal, being terminated prematurely for clinical reasons. Baseline Oxygen saturation was 93.3±8.8% and was 81.2±19.5% at peak exercise. A drop in arterial O2 saturation >20% was observed in 23.5% of the patients. Moreover, five patients (3.0%) experienced dizziness, one requiring termination of cardiopulmonary exercise testing; five children (3.0%) experienced chest pain, with early cardiopulmonary exercise test termination in one patient. No significant arrhythmias or electrocardiogram changes were observed.

CONCLUSION

Exercise testing in non-severely symptomatic children with pulmonary hypertension is safe and practical, and can be performed in a large number of children with pulmonary hypertension in a controlled environment with an experienced team. Side-effects were not serious and were resolved promptly with test termination.

Cardiopulmonary Exercise Testing and Prognosis in Hypertrophic Cardiomyopathy

Background—

Exercise testing is performed in patients with hypertrophic cardiomyopathy to evaluate blood pressure response, a risk factor for sudden cardiac death. The prognostic role of exercise gas exchange variables is unknown.

Methods and Results—

Between 1998 and 2010, 1898 patients (age 47±15 years, range 16–86 years; 67% male) with hypertrophic cardiomyopathy underwent cardiopulmonary exercise testing. A total of 178 (9.4%) patients reached the primary end point of all-cause mortality or heart transplant (death/transplant) during a median follow-up of 5.6 years (interquartile range 2.6–8.9), giving an annual event rate of 1.6% per person year. Peak oxygen consumption (adjusted hazard ratio [HR] 0.82, 95% confidence interval [CI] 0.77–0.88, P <0.001), ventilatory efficiency (adjusted HR 1.10, 95% CI 1.00–1.22, P =0.049), and ventilatory anaerobic threshold (adjusted HR 0.82, 95% CI 0.70–0.96, P =0.016) were predictors of the primary outcome after correction for age, sex, left atrial size, nonsustained ventricular tachycardia, and ejection fraction. The overall adjusted death/transplant estimates for patients in the lowest quartile with peak oxygen consumption ≤15.3 mL/kg/min were 14% at 5 years and 31% at 10 years. Peak oxygen consumption (HR 0.81, 95% CI 0.77–0.86, P <0.01) and ventilation to carbon dioxide production (HR 1.10, 95% CI 1.08–1.13, P <0.001) were predictors of death because of heart failure or transplantation but not sudden cardiac death or implantable cardioverter defibrillator shocks.

Conclusions—

Cardiopulmonary exercise testing provides prognostic information in patients with hypertrophic cardiomyopathy. Submaximal exercise parameters, such as ventilatory efficiency and anaerobic threshold, measured alone or in combination with peak oxygen consumption, predict death from heart failure.

Biomarkers in pediatric heart disease

A biomarker is a characteristic that can be used as an indicator of a biological state. A biomarker can be a clinical observation, laboratory test or an imaging parameter. In this review, we discuss the use of biomarkers in differentiating cardiac from noncardiac disease; predicting the prognosis of patients with heart failure, pulmonary hypertension and dilated cardiomyopathy; diagnosing subclinical cardiac involvement in muscular dystrophy and postchemotherapy cancer patients; detecting acute rejection following heart transplantation; diagnosing Kawasaki disease; aiding the management of postoperative cardiac patients; and managing both common (tetralogy of Fallot) and complex (single-ventricle physiology) congenital heart diseases.

Cardiopulmonary Exercise Testing in Children and Adolescents With Dystrophinopathies: A Pilot Study

PURPOSE

To determine exercise response during cardiopulmonary exercise testing in children and adolescents with dystrophinopathies.

METHODS

Exercise response on the cardiopulmonary exercise test (CPET) was compared with a standard care test protocol.

RESULTS

Nine boys (aged 10.8 ± 4.7 years) with Becker muscular dystrophy (n = 6) and Duchenne muscular dystrophy (n = 3) were included. The feasibility of the CPET was similar to a standard care test protocol, and no serious adverse events occurred. In 67% of the subjects with normal or only mildly impaired functional capacity, the CPET could be used to detect moderate to severe cardiopulmonary exercise limitations.

CONCLUSIONS

The CPET seems to be a promising outcome measure for cardiopulmonary exercise limitations in youth with mild functional limitations. Further research with larger samples is warranted to confirm current findings and investigate the additional value of the CPET to longitudinal follow-up of cardiomyopathy and the development of safe exercise programs for youth with dystrophinopathies.

Impairment of heart rate recovery after peak exercise predicts poor outcome after pediatric heart transplantation

BACKGROUND

A blunted heart rate recovery (HRR) from peak exercise is associated with adverse outcome in adults with ischemic heart disease. We assessed HRR after pediatric heart transplantation (HTx) and its prognostic use.

METHODS AND RESULTS

Between 2004 and 2010 we performed 360 maximal exercise tests (median, 2 tests/patient; range, 1-7) in 128 children (66 men; age at test, 14 ± 3 years) who received HTx (age, 8.5 ± 5.1 years) because of cardiomyopathy (66%) or congenital heart defects (34%). The change in heart rate from peak exercise to 1 minute of recovery was measured as HRR and was expressed as Z score calculated from reference data obtained in 160 healthy children. HRR was impaired soon after HTx (average in first 2 years Z=-1.9 ± 3.5) but improved afterward (Z=+0.52/y), such that HRR Z score normalized in most patients by 6 years after HTx (average, 0.6 ± 1.8). A subsequent decline in HRR Z score was noted from 6 years after HTx (rate of Z=-0.11/y). After 27 ± 15 months from the most recent exercise test, 19 patients died or were re-heart transplantation. For the follow-up after 6 years, HRR Z score was the only predictor of death/re-heart transplantation (P=0.003). Patients in the lowest quartile of HRR Z score had a much higher 5-year event rate (event-free rate, 29% versus 84%; hazard ratio, 7.0; P=0.0013).

CONCLUSIONS

HRR is blunted soon after HTx but normalizes at ≈ 6 years, potentially as a result of parasympathetic reinnervation of the graft, but then declines. This late decline in HRR Z score is associated with worse outcome.

Prognostic Value of Exercise Testing During Heart Transplant Evaluation in Children

Background—

Maximum oxygen consumption (peak VO 2 ) <50% predicted on exercise testing is a class I indication for heart transplant (HT) listing in children. This recommendation is based on exercise data in adults. We assessed the association of peak VO 2 <50% predicted during HT evaluation with freedom from death or deterioration in children.

Methods and Results—

We analyzed all children who underwent exercise testing during HT evaluation at our center between 2002 and 2011. Patients with peak VO 2 <50% predicted were compared with those with peak VO 2 ≥50% predicted for the composite outcome of death before HT, initiation of mechanical circulatory support, and HT at highest urgency status, using time-to-event analyses. There were 50 children in the study (median age, 15 years; interquartile range, 13–17 years; 24 girls; 18 with palliated single ventricle). Overall, 24 children reached the composite end point. Peak VO 2 <50% predicted was associated with outcome in children with biventricular circulation (hazard ratio, 4.7; 95% confidence interval, 1.8–12.3; P <0.001) but not in those with a palliated single ventricle (hazard ratio, 1.3; 95% confidence interval, 0.1–12.0; P =0.80). Similarly, VE/VCO 2 slope ≥34 was associated with outcome in children with biventricular circulation (hazard ratio, 2.7; 95% confidence interval, 1.1–7.1; P <0.001) but not in children with a palliated single ventricle.

Conclusions—

Exercise testing during HT evaluation in children with biventricular circulation identified those at higher risk of death or deterioration in this small study. Larger studies are needed to assess the role of exercise testing during HT evaluation in children with a palliated single ventricle.

Habitual exercise correlates with exercise performance in patients with conotruncal abnormalities

Cardiopulmonary exercise testing (CPET), particularly maximal oxygen consumption (VO2max), has been used to assess the outcome for patients with palliated congenital heart disease (CHD). Small studies correlating VO2max with noninvasive imaging measures of ventricular function have led to the hypothesis that VO2max reflects cardiac performance. In other settings, physical training is associated with increased VO2max. The authors hypothesized that habitual exercise correlates with VO2max to a greater degree than ventricular function in a relatively healthy cohort of patients with palliated CHD. The habitual exercise behavior of 208 subjects with conotruncal abnormalities (tetralogy of Fallot, truncus arteriosus, and interrupted aortic arch) at the time of previously performed, study-based CPET and cardiac magnetic resonance imaging (CMR) were retrospectively assessed via questionnaire. The association of VO2max with habitual exercise duration and CMR measures of ventricular function was tested. Of 208 subjects, 89 (43 %) completed questionnaires, and 78 % of the 89 patients had a concurrent CMR. The mean VO2max was 76 ± 21 % of that predicted. The CMR-assessed left ventricular ejection fraction was 67.6 ± 7.4 %. The hours of habitual exercise per week correlated with VO2max (p < 0.001; r (2) = 0.14). No association was found between right and left ventricular ejection fraction, cardiac index, or right ventricular end-diastolic volume and VO2max. In this study, VO2max correlated with habitual exercise to a greater degree than CMR measurements of ventricular function. These findings highlight the importance of considering the contribution of noncardiac factors when exercise data in both clinical and research settings are interpreted. The contribution of these factors to clinical outcomes deserves further study.

The Ross classification for heart failure in children after 25 years: a review and an age-stratified revision

Accurate grading of the presence and severity of heart failure (HF) signs and symptoms in infants and children remains challenging. It has been 25 years since the Ross classification was first used for this purpose. Since then, several modifications of the system have been used and others proposed. New evidence has shown that in addition to signs and symptoms, data from echocardiography, exercise testing, and biomarkers such as N-terminal pro-brain natriuretic peptide (NT-proBNP) all are useful in stratifying outcomes for children with HF. It also is apparent that grading of signs and symptoms in children is dependent on age because infants manifest HF differently than toddlers and older children. This review culminates in a proposed new age-based Ross classification for HF in children that incorporates the most useful data from the last two decades. Testing of this new system will be important to determine whether an age-stratified scoring system can unify the way communication of HF severity and research on HF in children is performed in the future.