The Role of Cardiopulmonary Exercise Testing for Decision Making in Patients with Repaired Tetralogy of Fallot

Exercise Capacity and Reoperation Late After Transatrial Fallot Repair

BACKGROUND

The exercise capacity long after repair of tetralogy of Fallot, when performed exclusively with a transatrial repair, is unclear. It is also unknown whether echocardiography and cardiopulmonary exercise testing can predict the risk of reoperation in this patient group.

METHOD

We retrospectively reviewed the clinical records of 59 patients who underwent cardiopulmonary exercise testing after transatrial Fallot repair at a single centre. Patients underwent cardiopulmonary exercise testing at a mean age of 16.6±4.4 years, and at 15.3±4.1 years after Fallot repair.

RESULTS

At testing, the volume of oxygen consumption at maximal exercise (VO2 max) was 71%±13% and the oxygen pulse was 80%±17% of predicted values. Seventeen (17) patients (29%) had a VO2 max superior to 80% of the predicted value. Thirty-two (32) patients (56%) had severe pulmonary regurgitation, three (5%) had moderate pulmonary regurgitation, and 12 (21%) had mild pulmonary regurgitation. After a mean of 7.8±3.9 years following cardiopulmonary exercise testing (23±5.3 years after the repair), 21 (40%) patients underwent reoperation. Right ventricular dilation and systolic function on echocardiography were both significantly associated with subsequent reoperation rates. Patients who had severe right ventricular dilation were eight times more likely to undergo subsequent reoperation (hazard ratio 8.67; 1.82-41.3; p=0.007). No cardiopulmonary exercise testing variable independently predicted reoperation.

CONCLUSIONS

The exercise capacity at adolescence following transatrial repair of tetralogy of Fallot is maintained at around 70% of predicted values. Only the patients with normal right ventricular size and normal right ventricular function seemed to be protected from reoperation over the subsequent decade. We found no exercise variables which predicted reoperation.

Characterizing the Use of Exercise Testing in Repaired Tetralogy of Fallot Patients: A Multi-Institutional Survey

Cardiopulmonary exercise testing (CPET) is an important tool used in the management of patients with congenital heart disease. However, there are no clear guidelines for its use in specific populations, such as repaired Tetralogy of Fallot (rTOF). We sought to characterize current practice patterns and attitudes regarding exercise testing in the rTOF population using an online survey distributed to pediatric cardiologists. Analyses were performed using qualitative statistics, Wilcoxon rank-sum, Kruskal-Wallis test, and chi-squared analysis. 103 clinicians completed the survey with 83% routinely sending symptomatic rTOF patients for exercise testing and 59% for asymptomatic patients. Respondents who routinely test asymptomatic patients reported higher levels of perceived helpfulness of exercise testing (p < 0.01) and comfort with CPET interpretation (p < 0.01). Although a large majority of respondents found exercise testing to be helpful (81% either "somewhat" or "very" helpful"), a considerably smaller portion indicated comfort with CPET interpretation (49% either "comfortable" or "very comfortable"). Nearly all respondents (92%) reported changing management primarily based on exercise testing results. However, the frequency of changes varied, with 10% "frequently", 62% "occasionally", 19% "rarely" changing management. There was a statistically significant relationship between the perceived helpfulness of exercise testing and the likelihood of management changes (p < 0.01). While exercise testing is used to make clinical decisions, our findings suggest that in some cases, management changes may be made without a similar degree of confidence in interpreting CPET findings. The variability in attitudes and practices highlights the need for evidence-based guidelines addressing exercise testing in rTOF, particularly for asymptomatic patients.

Physical Activity Promotion Among Individuals With Tetralogy of Fallot

In the general population, the most cited barriers to physical activity (PA) are time, energy, and motivation. Consequently, despite the significant contribution of PA to health and well-being, many individuals are insufficiently active. Physical inactivity and sedentary lifestyles increase the risk of acquired cardiometabolic disease, a risk that may complicate and is compounded by the anatomic and physiologic features inherent in the patient with repaired tetralogy of Fallot (ToF). Individuals with ToF commonly present with reduced exercise capacity and PA levels. In light of historically PA restrictive management of their heart disease, known reductions in exercise capacity among individuals with ToF are combined with psychosocial barriers to their participation, potentially establishing a cycle of further detraining, inactivity, and disease progression/health decline. To this end, children and young adults with ToF are known to have reduced self-efficacy towards PA, defined as their confidence in their ability to participate. In this review, we apply self-efficacy as an overarching mediator of PA participation and explore trends and determinants of PA participation among individuals with ToF and its subsequent impact on exercise capacity, disease risk, and health-related quality of life. We outline the rationale and strategies aimed at improving PA in children and adults with ToF and highlight current knowledge gaps and future directions in the promotion of PA in the population with ToF.

Multimodality Imaging Assessment of Tetralogy of Fallot: From Diagnosis to Long-Term Follow-Up

Tetralogy of Fallot (TOF) is the most common complex congenital heart disease with long-term survivors, demanding serial monitoring of the possible complications that can be encountered from the diagnosis to long-term follow-up. Cardiovascular imaging is key in the diagnosis and serial assessment of TOF patients, guiding patients' management and providing prognostic information. Thorough knowledge of the pathophysiology and expected sequalae in TOF, as well as the advantages and limitations of different non-invasive imaging modalities that can be used for diagnosis and follow-up, is the key to ensuring optimal management of patients with TOF. The aim of this manuscript is to provide a comprehensive overview of the role of each modality and common protocols used in clinical practice in the assessment of TOF patients.

Characterizing the Use of Exercise Testing in Repaired Tetralogy of Fallot Patients: A Multi-Institutional Survey

Long-term survival for repaired Tetralogy of Fallot (rTOF) is excellent. We achieve this by close clinical monitoring to stratify prognosis and guide clinical decision-making. Cardiopulmonary exercise stress testing (CPET) is used to help guide clinical decision making; however, there are no clear guidelines for its use in this population. We sought to describe practice variability with regards to exercise testing for rTOF patients and how exercise data is used to guide management. We distributed a survey to pediatric cardiologists via email. Analyses were performed using qualitative statistics, two-sample T-tests, and chi-squared analysis. One-hundred and three clinicians completed the survey with 83% reporting that they routinely send symptomatic rTOF patients for exercise testing and 59% for asymptomatic patients. Respondents who routinely test asymptomatic patients reported higher levels of perceived helpfulness of exercise testing (p = 0.04) and comfort with CPET interpretation (p = 0.03). Nearly all respondents (92%) reported changing management primarily based on exercise testing results, with 62% reporting "occasionally changing management" and 10% reporting "frequently changing management". Results indicated that exercise test results influenced clinical decisions, such as the timing of interventions, need for additional imaging, or the initiation of exercise interventions. There was a statistically significant relationship between the perceived helpfulness of exercise testing and the likelihood of management changes (p < 0.01). The variability in attitudes and practices highlights the need for evidence-based guidelines addressing exercise testing in rTOF, particularly for asymptomatic patients.

Exercise Pathophysiology and Testing in Individuals With a Fontan Circulation

The Fontan circulation, a surgical palliation for single-ventricle congenital heart disease, profoundly impacts the cardiopulmonary response to exercise. Reliant on passive pulmonary blood flow, the Fontan circulation has limited capacity to augment cardiac output as necessary to supply working muscles during exercise. Cardiopulmonary exercise testing (CPET) objectively assesses cardiorespiratory fitness and provides insight into the etiology of exercise intolerance. Furthermore, CPET variables, such as peak oxygen consumption and submaximal variables, have prognostic value and may be used as meaningful endpoints in research studies. CPET is also useful in clinical research applications to assess the effect of pharmacologic or other interventions. Medical therapies to improve exercise tolerance in individuals with a Fontan circulation, such as pulmonary vasodilators, may modestly improve peak oxygen consumption. Exercise training focused on aerobic fitness and lower extremity strength may have a more consistent and larger impact on these measures of aerobic fitness. CPET is a valuable diagnostic and prognostic tool for those with a Fontan circulation. Newer ancillary assessments, such as noninvasive peripheral venous pressure monitoring and cardiac output measurements, hold promise to provide a more nuanced insight into the underlying pathophysiology.

Development of a Pediatric Cardiology Cardiopulmonary Exercise Testing Database

Cardiopulmonary exercise testing (CPET) provides clinicians with information vital to the management of pediatric cardiology patients. CPET can also be used to measure cardiorespiratory fitness (CRF) in these patients. CRF is a robust marker of overall health in children. However, a complete understanding of CRF in pediatric cardiology patients is limited by lack of large, standardized CPET databases. Our purpose was to develop a standardized CPET database, describe available data at our institution, and discuss challenges and opportunities associated with this project. CPETs performed from 1993 to present in an urban pediatric hospital were collected and compiled into a research database. Historical data included demographic and clinical variables and CPET outcomes, and additional variables were calculated and coded to facilitate analyses in these cohorts. Patient diagnoses were coded to facilitate sub-analyses of specific cohorts. Quality assurance protocols were established to ensure future database contributions and promote inter-institutional collaborations. This database includes 10,319 CPETs (56.1% male), predominantly using the Bruce Protocol. Patients ranging from ages 6 to 18 years comprise 86.8% of available CPETs. Diagnosis classification scheme includes patients with structurally normal hearts (n = 3,454), congenital heart disease (n = 3,614), electrophysiological abnormalities (n = 2,082), heart transplant or cardiomyopathy (n = 833), and other diagnoses (n = 336). Historically, clinicians were provided with suboptimal interpretive resources for CPET, often generalizing inferences from these resources to non-representative clinical populations. This database supports representative CRF comparisons and establishes a framework for future CRF-based registries in pediatric patients referred for CPET, ultimately improving clinical decision-making regarding fitness in these populations.

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.

Cardiopulmonary Exercise Testing in Repaired Tetralogy of Fallot: Multiparametric Overview and Correlation with Cardiac Magnetic Resonance and Physical Activity Level

Patients with repaired Tetralogy of Fallot (rToF) typically report having preserved subjective exercise tolerance. Chronic pulmonary regurgitation (PR) with varying degrees of right ventricular (RV) dilation as assessed by cardiac magnetic resonance imaging (MRI) is prevalent in rToF and may contribute to clinical compromise. Cardiopulmonary exercise testing (CPET) provides an objective assessment of functional capacity, and the International Physical Activity Questionnaire (IPAQ) can provide additional data on physical activity (PA) achieved. Our aim was to assess the association between CPET values, IPAQ measures, and MRI parameters. All rToF patients who had both an MRI and CPET performed within one year between March 2019 and June 2021 were selected. Clinical data were extracted from electronic records (including demographic, surgical history, New York Heart Association (NYHA) functional class, QRS duration, arrhythmia, MRI parameters, and CPET data). PA level, based on the IPAQ, was assessed at the time of CPET. Eighty-four patients (22.8 ± 8.4 years) showed a reduction in exercise capacity (median peak VO₂ 30 mL/kg/min (range 25–33); median percent predicted peak VO₂ 68% (range 61–78)). Peak VO₂, correlated with biventricular stroke volumes (RVSV: β = 6.11 (95%CI, 2.38 to 9.85), p = 0.002; LVSV: β = 15.69 (95% CI 10.16 to 21.21), p < 0.0001) and LVEDVi (β = 8.74 (95%CI, 0.66 to 16.83), p = 0.04) on multivariate analysis adjusted for age, gender, and PA level. Other parameters which correlated with stroke volumes included oxygen uptake efficiency slope (OUES) (RVSV: β = 6.88 (95%CI, 1.93 to 11.84), p = 0.008; LVSV: β = 17.86 (95% CI 10.31 to 25.42), p < 0.0001) and peak O₂ pulse (RVSV: β = 0.03 (95%CI, 0.01 to 0.05), p = 0.007; LVSV: β = 0.08 (95% CI 0.05 to 0.11), p < 0.0001). On multivariate analysis adjusted for age and gender, PA level correlated significantly with peak VO₂/kg (β = 0.02, 95% CI 0.003 to 0.04; p = 0.019). We observed a reduction in objective exercise tolerance in rToF patients. Biventricular stroke volumes and LVEDVi were associated with peak VO₂ irrespective of RV size. OUES and peak O₂ pulse were also associated with biventricular stroke volumes. While PA level was associated with peak VO₂, the incremental value of this parameter should be the focus of future studies.

Italian Cardiological Guidelines (COCIS) for Competitive Sport Eligibility in athletes with heart disease: update 2020

Since 1989, SIC Sport and a FMSI, in partnership with leading Italian Cardiological Scientific Associations (ANCE, ANMCO and SIC) have produced Cardiological Guidelines for Completive Sports Eligibility for athletes with heart disease (COCIS -- 1989, 1995, 2003, 2009 and 2017). The English version of the Italian Cardiological Guidelines for Competitive Sports Eligibility for athletes with heart disease was published in 2013 in this Journal. This publication is an update with respect to the document previously published in English in 2013. It includes the principal innovations that have emerged over recent years, and is divided into five main chapters: arrhythmias, ion channel disorders, congenital heart diseases, acquired valve diseases, cardiomyopathies, myocarditis and pericarditis and ischemic heart disease. Wherever no new data have been introduced with respect to the 2013 publication, please refer to the previous version. This document is intended to complement recent European and American guidelines but an important difference should be noted. The European and American guidelines indicate good practice for people engaging in physical activity at various levels, not only at the competitive level. In contrast, the COCIS guidelines refer specifically to competitive athletes in various sports including those with high cardiovascular stress. This explains why Italian guidelines are more restrictive than European and USA ones. COCIS guidelines address 'sports doctors' who, in Italy, must certify fitness to participate in competitive sports. In Italy, this certificate is essential for participating in any competition.

Better preoperative exercise function is associated with shorter hospital stay after paediatric pulmonary valve replacement or conduit revision

Exercise capacity is a modifiable factor in patients with CHD that has been related to surgical outcomes in adults. We hypothesised that this was true for children undergoing surgical pulmonary valve replacement; therefore, the relationship of preoperative percent predicted peak oxygen consumption to surgical outcomes as measured by total hospital length of stay was explored.

METHODS

Single centre retrospective cohort study of patients aged 8-18 years who underwent surgical pulmonary valve replacement. The primary predictor was preoperative percent predicted peak oxygen consumption, and primary outcome was total hospital length of stay. Clinical, imaging, and cardiopulmonary exercise test data were reviewed and compared to total hospital length of stay. Cox proportional hazards regression was used to examine the association between total hospital length of stay and percent predicted peak oxygen consumption.

RESULTS

Three-hundred and seventy patients undergoing pulmonary valve replacement/conduit change between 2003 and 2017 at Boston Children's Hospital were identified. Ninety had preoperative cardiopulmonary exercise tests within 6 months of surgery. Exclusion for inadequate exercise data (n = 3) and imaging data (n = 1) left 86 patients for review. Patients with percent predicted peak oxygen consumption ≥ 70% (n = 46, 53%) had shorter total hospital length of stay (4.4 days) than the 40 with percent predicted peak oxygen consumption <70% (5.4 days, p = 0.007). Median percent predicted peak oxygen consumption increased over sequential surgical eras (p < 0.001), but total hospital length of stay did not correlate with surgical era, preoperative left ventricular function, or preoperative right ventricular dilation.

CONCLUSION

Children undergoing surgical pulmonary valve replacement with better preoperative exercise capacity had shorter total hospital length of stay. Exercise capacity is a potentially modifiable factor prior to and after pulmonary valve replacement. Until more patients systematically undergo cardiopulmonary exercise tests, the full impact of optimisation of exercise capacity will not be known.

Bicycle spiroergometry: comparison of standardized examination protocols for adolescents: is it necessary to define own standard values for each protocol?

Purpose

To compare performance data of adolescents collected with five different bicycle spiroergometry protocols and to assess the necessity for establishing standard values for each protocol.

Methods

One-hundred-twenty adolescents completed two bicycle spiroergometries within 14 days. One of the two tests was performed based on our institutional weight-adapted protocol (P0). The other test was performed based on one out of four exercise protocols widely used for children and adolescents (P1, 2, 3 or 4) with 30 persons each. The two tests were performed in a random order. Routine parameters of cardiopulmonary exercise tests (CPET) such as VO₂peak, maximum power, O₂ pulse, OUES, VE/VCO₂ slope as well as ventilatory and lactate thresholds were investigated. Agreement between protocols was evaluated by Bland–Altman analysis, coefficients of variation (CV) and intra-class correlation coefficients (ICC).

Results

None of the CPET parameters were significantly different between P0 and P1, 2, 3 or 4. For most of the parameters, low biases between P0 and P1–P4 were found and 95% confidence intervalls were narrow. CV and ICC values largely corresponded to well-defined analytical goals (CV < 10% and ICC > 0.9). Only maximal power (Pmax) showed differences in size and drift of the bias depending on the length of the step duration of the protocols.

Conclusion

Comparability between examination protocols has been shown for CPET parameters independent on step duration. Protocol-dependent standard values do not appear to be necessary. Only Pmax is dependent on the step duration, but in most cases, this has no significant influence on the fitness assessment.

Prognostic markers in patients undergoing transcatheter implantation of Venus P-valve: Experience in Taiwan

BACKGROUND/PURPOSE

Prognostic factors remain unclear in patients undergoing transcatheter implantation of Venus P-valve for their severe pulmonary regurgitation associated with native right ventricular (RV) outflow tract.

METHOD

Between January 2017 and October 2018, we prospectively collected data of patient characteristics, cardiac magnetic resonance imaging, cardiopulmonary exercise testing, and levels of N-terminal pro-B-type natriuretic peptide (NT-proBNP) before and 6-12 months after valve graft implantation.

RESULTS

Fifteen patients (male: 8, median age: 24.8 years) were enrolled. The procedure success rate was 100%. The median follow-up was 16.3 months without any dysfunction of the valve graft. The cohort demonstrated a significant improvement in cardiac index (from 3.3 to 3.9 L/min/m²) and increase of percentage of New York Heart Association functional class I (P < 10^-3), reduction in RV end-diastolic volume index (P = 0.008), and reductions in NT-proBNP levels (from 78.9 to 45.8 pg/mL, P = 0.040). However, the peak oxygen consumption (VO₂) dropped from 50.2% to 48.5% of the predicted value. Interestingly, we determined that patients with NT-proBNP levels below 70 pg/mL and left ventricular end-diastolic pressure (LVEDP) below 11 mmHg had a significantly higher chance of exhibiting improvement in peak VO₂ compared with those without (3/4 vs 1/10, P = 0.041).

CONCLUSION

In the small cohort with severe pulmonary regurgitation, implantation of a Venus P-valve led to promising reductions in RV volume. However, no definite improvement in cardiopulmonary exercise capacity or RV ejection fraction was achieved. Levels of NT-proBNP and LVEDP may be helpful for refining the indications of the Venus P-valve implantation.

Modified Ventricular Global Function Index Correlates With Exercise Capacity in Repaired Tetralogy of Fallot

Background

Cardiac MRI (CMR) derived ventricular global function index (GFI), a ratio of stroke volume to the sum of mean ventricular cavity and myocardial volumes, has demonstrated improved prediction of clinical outcomes in adults with atherosclerotic disease over ejection fraction. We sought to assess CMR derived GFI and a novel modification that accounts for unique loading conditions in patients with repaired tetralogy of Fallot (rTOF) and determine its correlation with exercise performance.

Methods and Results

Seventy‐five patients with rTOF who underwent CMR were identified. Clinical variables were recorded and biventricular GFI calculated. A right ventricular (RV) effective GFI (eGFI) was derived by incorporating effective stroke volume. Thirty‐five pediatric patients were matched with 29 age‐matched healthy controls. Twenty‐five patients completed cardiopulmonary exercise tests within 6 months of CMR. Stepwise regression models were used to determine univariate and multivariable predictors of indexed and percent predicted peak VO₂. Median age at CMR was 20 years (interquartile range, 13–28). Pediatric rTOF patients had lower RV eGFI (P < 0.001), RV ejection fraction (P=0.002), but higher indexed RV end‐diastolic and end‐systolic volumes (P < 0.001, P < 0.001) compared with controls. Univariate analysis demonstrated a correlation between indexed peak VO₂ with RV eGFI (R²=0.32, P=0.004), but with neither RVGFI, RV ejection fraction, indexed RV volumes nor RV mass. RV eGFI remained significantly associated with indexed peak VO₂ during multivariable modeling.

Conclusions

Reduced RV eGFI was associated with reduced exercise capacity in rTOF patients, while RV GFI, RV ejection fraction, indexed RV volumes and mass were not. Our modification of the GFI, RV eGFI, may be a valuable non‐invasive marker of cardiac function in rTOF.

Does Restrictive Lung Function Affect the Exercise Capacity in Patients with Repaired Tetralogy of Fallot?

Patients with repaired Tetralogy of Fallot (rTOF) have decreased exercise capacity (XC) and restrictive lung function (RLF). Our objective was to determine the association between RLF and impaired XC in patients with rTOF. This was a single center retrospective review of patients with rTOF who underwent a cardiopulmonary treadmill exercise testing and spirometry from 2005 to 2015. Patients with a respiratory exchange ratio ≥ 1.05 and peak heart rate > 90% of predicted value were included. Forced vital capacity (FVC) and Forced expiratory volume in 1st second of forceful expiration (FEV₁) were used to classify the lung function. Exercise parameters such as peak oxygen uptake (VO₂), % of predicted VO₂ (%VO₂), Metabolic equivalents (METS), and exercise time (ET) were compared between the two groups (i) compared patients with normal lung function (normal FEV₁, FVC, and FEV₁/FVC > 80%) (ii) RLF (FVC < 80%, normal or increased FEV₁/FVC > 80%). In our cohort (n = 151, 52% male, mean age ± SD of 22.3 ± 9.1 years), patients with RLF (n = 73) compared to those with normal lung function (n = 86) had a lower peak VO₂ (30.8 ± 8.6 vs. 36.6 ± 9.8 mL/kg/min; p < 0.001) and shorter exercise time (9:23 ± 1:78 vs. 10:23 ± 1:62 min, p < 0.001). On multivariate regression analysis, RLF was independently associated with reduced XC (VO₂%) (β-coefficient - 0.182, p < 0.02) after controlling for age and gender. RLF is common in patients with rTOF and is associated with decreased XC. The contribution of RLF to reduced XC in this population should be considered prior to therapeutic decisions.

Results of the FUEL Trial

BACKGROUND

The Fontan operation creates a total cavopulmonary connection, a circulation in which the importance of pulmonary vascular resistance is magnified. Over time, this circulation leads to deterioration of cardiovascular efficiency associated with a decline in exercise performance. Rigorous clinical trials aimed at improving physiology and guiding pharmacotherapy are lacking.

METHODS

The FUEL trial (Fontan Udenafil Exercise Longitudinal) was a phase III clinical trial conducted at 30 centers. Participants were randomly assigned udenafil, 87.5 mg twice daily, or placebo in a 1:1 ratio. The primary outcome was the between-group difference in change in oxygen consumption at peak exercise. Secondary outcomes included between-group differences in changes in submaximal exercise at the ventilatory anaerobic threshold, the myocardial performance index, the natural log of the reactive hyperemia index, and serum brain-type natriuretic peptide.

RESULTS

Between 2017 and 2019, 30 clinical sites in North America and the Republic of Korea randomly assigned 400 participants with Fontan physiology. The mean age at randomization was 15.5±2 years; 60% of participants were male, and 81% were white. All 400 participants were included in the primary analysis with imputation of the 26-week end point for 21 participants with missing data (11 randomly assigned to udenafil and 10 to placebo). Among randomly assigned participants, peak oxygen consumption increased by 44±245 mL/min (2.8%) in the udenafil group and declined by 3.7±228 mL/min (-0.2%) in the placebo group (P=0.071). Analysis at ventilatory anaerobic threshold demonstrated improvements in the udenafil group versus the placebo group in oxygen consumption (+33±185 [3.2%] versus -9±193 [-0.9%] mL/min, P=0.012), ventilatory equivalents of carbon dioxide (-0.8 versus -0.06, P=0.014), and work rate (+3.8 versus +0.34 W, P=0.021). There was no difference in change of myocardial performance index, the natural log of the reactive hyperemia index, or serum brain-type natriuretic peptide level.

CONCLUSIONS

In the FUEL trial, treatment with udenafil (87.5 mg twice daily) was not associated with an improvement in oxygen consumption at peak exercise but was associated with improvements in multiple measures of exercise performance at the ventilatory anaerobic threshold.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT02741115.

Functional Capacity Is Affected by Younger Age of Repair in Tetralogy of Fallot Patients But Not by Era of Repair

Background:

Cardiopulmonary exercise testing is widely used to assess functional capacity in patients with tetralogy of Fallot after surgical repair. Little is known regarding the impact of age at the time of primary complete repair and surgical era effect on exercise capacity.

Methods:

A retrospective, single-center chart review was done from 1976 to 2016 on pediatric patients with tetralogy of Fallot who underwent cardiopulmonary exercise testing with cycle ergometry utilizing the James protocol and were then sorted by repair before/after 1990 and by age of complete repair before/after one year. Exclusion criteria included submaximal tests, incomplete data, previous pulmonary valve replacement, and surgery prior to complete repair (ie, Blalock-Taussig shunt placement).

Results:

When comparing the groups who underwent primary complete repair before (N = 39) and after (N = 26) one year of age, the younger group demonstrated a higher percentage of predicted peak oxygen consumption ([Formula: see text] o2peak; 83.1% ± 11.8% vs 73.1% ± 16.1%; P = .005) despite having worse pulmonary insufficiency at the time of exercise testing. There were no differences in heart rate and blood pressure response. Age of repair was independently associated with [Formula: see text] o2peak. Data were statistically similar to the study eras (repair before 1990, N = 23; repair after 1990, N = 65): percentage of predicted [Formula: see text] o2peak (81.4% ± 13.6% vs 79.1% ± 14.4%, P = .5), maximal systolic blood pressure (155.1 ± 22.4 mm Hg vs 153.9 ± 17 mm Hg, P = .8), and percentage of predicted maximal heart rate (89.8% ± 9% vs 92% ± 7.1%, P = .3).

Conclusions:

Older age at primary repair appears to negatively impact [Formula: see text] o2peak; however, era effect does not appear to influence cardiopulmonary exercise testing outcomes.

Hemodynamic Changes During Physiological and Pharmacological Stress Testing in Healthy Subjects, Aortic Stenosis and Aortic Coarctation Patients-A Systematic Review and Meta-Analysis

Introduction: Exercise testing has become a diagnostic standard in the evaluation and management of heart disease. While different methods of exercise and pharmacological stress testing exist, only little is known about their comparability. We aimed to assess hemodynamic changes during dynamic exercise, isometric exercise, and dobutamine stress testing at different stress intensities in healthy subjects and patients with aortic stenosis (AS) and aortic coarctation (CoA).

Methods: A systematic literature search (PROSPERO 2017:CRD42017078608) in MEDLINE of interventional trials was conducted to identify eligible studies providing evidence of changes in hemodynamic parameters under different stress conditions acquired by MRI or echocardiography. A random effects model was used to estimate pooled mean changes in hemodynamics.

Results: One hundred and twenty-eight study arms with a total of 3,139 stress-examinations were included. In healthy subjects/(where available) in AS, pooled mean changes (95% CIs) during light dynamic stress were 31.78 (27.82–35.74) bpm in heart rate (HR) and 6.59 (2.58–10.61) ml in stroke volume (SV). Changes during light pharmacological stress were 13.71 (7.87–19.56)/14.0 (9.82–18.18) bpm in HR, and 5.47 (0.3–10.63)/8.0 (3.82–12.18) ml in SV. Changes during light isometric stress were 18.44 (10.74–26.14)/5.0 (−1.17–11.17) bpm in HR and −4.17 (−14.37–6.03)/−4.0 (−16.43–8.43) ml in SV. Changes during moderate dynamic stress were 49.57 (40.03–59.1)/46.45 (42.63–50.27) bpm in HR and 11.64 (5.87–17.42) ml in SV. During moderate pharmacological stress, changes in HR were 42.83 (36.94–48.72)/18.66 (2.38–34.93) bpm and in SV 6.29 (−2.0–14.58)/13.11 (7.99–18.23) ml. During high intensity dynamic stress changes in HR were 89.31 (81.46–97.17)/55.32 (47.31–63.33) bpm and in SV 21.31 (13.42–29.21)/−0.96 (−5.27–3.35) ml. During high pharmacological stress, changes in HR were 53.58 (36.53–70.64)/42.52 (32.77–52.28) bpm, and in SV 0.98 (−9.32–11.27)/14.06 (−1.62–29.74) ml. HR increase and age were inversely correlated at high stress intensities. In CoA, evidence was limited to single studies.

Conclusion: This systematic review and meta-analysis presents pooled hemodynamic changes under light, moderate and high intensity exercise and pharmacological stress, while considering the potential influence of age. Despite limited availability of comparative studies, the reference values presented in this review allow estimation of the expected individual range of a circulatory response in healthy individuals and patients with AS and may contribute to future study planning and patient-specific models even when stress testing is contraindicated.

New Reference Values for Cardiopulmonary Exercise Testing in Children

INTRODUCTION

Cardiopulmonary exercise testing is an essential tool to assess cardiorespiratory fitness (CRF) in children. There is a paucity of adequate pediatric reference values that are independent of body size and pubertal stage. The purpose of this study is to provide Z score equations for several maximal and submaximal CRF parameters derived from a prospectively recruited sample of healthy children.

METHODS

In this cross-sectional multicenter study, we prospectively recruited 228 healthy children 12 to 17 yr old in local schools. We performed a symptom-limited cardiopulmonary exercise testing progressive ramp protocol on an electronically braked cycle ergometer. Eighteen CRF parameters were analyzed. We tested several regression models to obtain prediction curves that minimized residual association with age, body size, and pubertal stage. Both the predicted mean and the predicted SD were modeled to account for heteroscedasticity.

RESULTS

We identified nonlinear association of CRF parameters with body size and significant heteroscedasticity. To normalize CRF parameters, the use of a single body size variable was not sufficient. We therefore used multivariable models with various combination of height, corrected body mass, and age. Final prediction models yielded adjusted CRF parameters that were independent of age, sex, body mass, height, body mass index, and Tanner stages.

CONCLUSIONS

We present Z score equations for several CRF parameters derived from a healthy pediatric population. These reference values provide updated predicted means and range of normality that are independent of sex and body size. Further testing is needed to assess if these reference values increase sensitivity and specificity to identify abnormal cardiorespiratory response in children with chronic diseases.

A prospective 5-year study of exercise performance following Melody valve implant

BACKGROUND

The long-term benefits of Melody valve implant for right ventricular outflow tract conduit obstruction or insufficiency on exercise capacity are undefined.

METHODS

As part of the Melody valve clinical trial, 136 patients with congenital heart disease underwent serial cardiopulmonary exercise testing prior to, 6 months after, and annually for up to 5 years postimplant.

RESULTS

Mean age at Melody valve implantation was 22.4 ± 0.9 years (range 7-53 years). The 95 patients who completed the study protocol provide the basis of this report. An initial improvement in % predicted workload was present at 6 months postimplant; however, at the final (5 year) follow-up, sustained or further improvements in workload were not demonstrated for the entire cohort compared to baseline. By subgroup analysis, age <17 years at implant and pulmonary regurgitation as the primary lesion were variables associated with sustained improvement in exercise performance. There were sustained improvements in the ventilatory equivalents for O₂ (minute ventilation/O₂ intake, P = .01) and CO₂ (minute ventilation/CO₂ output, P < .01) at the ventilatory anaerobic threshold at the study conclusion. Improvements in forced vital capacity were also observed during the study but not sustained at the final follow-up.

CONCLUSIONS

A cautious appraisal of the cardiovascular benefits of Melody valve implant on sustained improvements in exercise performance appears warranted. Although the observed changes in pulmonary function suggest improved restrictive lung physiology and more efficient gas exchange, after an initial increase in % predicted performance, neither sustained nor further improvements in exercise performance were observed, except in specific patient subgroups.

Impact of Percutaneous Pulmonary Valve Implantation on the Timing of Reintervention for Right Ventricular Outflow Tract Dysfunction

Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart defect. Early surgical repair has dramatically improved the outcome of this condition. However, despite the success of contemporary approaches with early complete repair, these are far from being curative and late complications are frequent. The most common complication is right ventricle outflow tract (RVOT) dysfunction, affecting most patients in the form of pulmonary regurgitation, pulmonary stenosis, or both, and can lead to development of symptoms of exercise intolerance, arrhythmias, and sudden cardiac death. Optimal timing of restoration of RVOT functionality in asymptomatic patients with RVOT dysfunction after TOF repair is still a matter of debate. Percutaneous pulmonary valve implantation, introduced almost 2 decades ago, has become a major game-changer in the treatment of RVOT dysfunction. In this article we review the pathophysiology, the current indications, and treatment options for RVOT dysfunction in patients after TOF repair with a focus on the role of percutaneous pulmonary valve implantation in the therapeutic approach to these patients.