Nowadays, biomarkers are broadly used in clinical practice. Blood-derived biomarkers fulfil an important role in the field of cardiology. However, most biomarkers have been investigated for adult left ventricular disease. In congenital heart diseases (CHD) and pulmonary arterial hypertension (PAH), which involves children and mostly the right ventricle, less is known about the clinical and predictive value of blood-derived biomarkers. Since the group of survivors of CHD and PAH is growing because of the improved techniques nowadays, development of better tools to maintain the quality of life for the longer term in these patients is urgently needed. Blood-derived biomarkers are minimally invasive biomarkers, are quantitative and have shown to be able to reveal pathological processes in an early stage. Hence, blood-derived biomarkers may be a good addition to current diagnostic means in CHD and PAH.

Objective: The primary objective of this study is to investigate cross-sectionally the association between various emerging blood-derived biomarkers and right ventricular (RV) function:defined as tricuspid annular plane systolic excursion (TAPSE) measured with echocardiography, in children with (a history of ) an abnormally loaded, volume and/or pressure loaded, right ventricle associated with CHD and/or PAH.

OBJECTIVES:

Primary Objective:

The primary objective is to investigate cross-sectionally (at baseline and after one year) the association between various emerging blood-derived biomarkers and right ventricular (RV) function:defined as tricuspid annular plane systolic excursion (TAPSE) measured with echocardiography, in children with (a history of ) an abnormally loaded, volume and/or pressure loaded, right ventricle associated with CHD and/or PAH.

TIME FRAME: Baseline and after one year.

Secondary Objective:

Furthermore, the investigators aim to explore:

• The stability, dynamic (treatment-induced) longitudinal changes of these biomarkers and their association with RV function (defined as TAPSE).
• The predictive value of these biomarkers measured at baseline with regard to various clinically relevant impaired RV functioning parameters (TAPSE, RV- Fractional area change , RV-Fractional shortening and RV function assessed with eyeballing) at long term follow-up.
• The predictive value of these biomarkers with regard to clinical outcome defined as the composite of mortality, hospitalization, and or heart/lung transplantation.

STUDY POPULATION: All patients with (a history of) an abnormally loaded right ventricle associated with CHD and/or PAH who are followed in the Center of Congenital Heart Disease - University Medical Center Groningen (CHH-UMCG) from 01-12-2017 will be approached by letter and telephone to be included.

STUDY PROCEDURES:

1. The study is introduced to the patient and his/her parents/legal representatives by letter and telephone. When the patient or his/her parents/legal representatives are interested the researcher will ask them to sign informed consent papers. When the patient is admitted to the clinical ward or will come for his/her outpatient clinic visit the researcher will check if informed consent has been given. If informed consent has been given and the patient meets the inclusion criteria he/she will be included in the study.

2. Study procedures with respect to primary comparison:

   Echocardiography will be performed in all included patients (100%) in context of standard care. Blood drawing in context of standard care or additional study purposes will be performed in all included patients (100%).

3. Study procedures (all performed in context of standard care) with respect to secondary comparisons: Mortality will be assessed in all patients (±100%).Functional class will be clearly documented in most included patients (±80%).MRI will be performed in a subpopulation of included patients (±50%).CPET will be performed in a subpopulation of included patients (±40%). 6MWD will be performed in a subpopulation included patients (±30%).

WITHDRAWAL OF INDIVIDUAL SUBJECTS: Subjects can leave the study at any time for any reason if they wish to do so without any consequences. The investigator can decide to withdraw a subject from the study for urgent medical reasons.

REPLACEMENT OF INDIVIDUAL SUBJECTS AFTER WITHDRAWAL: Withdrawal before the first time point will result in exclusion. Withdrawal after the first time point will result in a smaller sample size regarding to follow up, but the data will still be used for the available time points.

PREMATURE TERMINATION: premature termination has no influence on the patients.

ADMINISTRATIVE ASPECTS, MONITORING AND PUBLICATION:

1. In this study the data will be coded according to a protected key on the general Beatrix Children's Hospital (BKK)-disk. Data will be collected in RedCap or Utopia, which both meet the security requirements according to legislation described by BROK and UMCG.

   All included patients will get a study identification number: BioCHD001, BioCHD002, etc. The order will be in the order of the obtained informed consent. The key will be available at the general BKK-disk for above mentioned investigators and contains the original patient number (UMCG-number), study identification number (study ID), and study identification number of other studies the patient is involved in.

   Data entry will be based on information from Epic, Poliplus, ECHOPAC (for echocardiography) or Medis QMass (for MRI). The blood samples will be stored on study ID by the central laboratory and assessments of the blood-derived biomarkers will be performed by the central laboratory as well. Blood results will be communicated according to study ID.

   Data will be stored in the central laboratory until all the different assays have been run. Data will be kept 15 years after end-of-study. Conditions for long-term document storage will follow GCP, institutional and national guidelines.

2. Monitoring and Quality Assurance : Monitoring will take place according to guidelines in Research Toolbox on UMCG-intranet.

3. Annual progress report: The sponsor/investigator will submit a summary of the progress of the trial to the accredited METC once a year. Information will be provided on the date of inclusion of the first subject, numbers of subjects included and numbers of subjects that have completed the trial, serious adverse events/ serious adverse reactions, other problems, and amendments.

4. Public disclosure and publication policy: This prospective study will be registered prospectively at the website www.toetsingonline.nl and clintrail.gov.

The results of the study will be published without reservations at international conferences and will be submitted for publication in international "peer-reviewed" scientific journals.

SAFETY REPORTING:

1. Temporary halt for reasons of subject safety:

   In accordance to section 10, subsection 4, of the WMO, the sponsor will suspend the study if there is sufficient ground that continuation of the study will jeopardise subject health or safety. The sponsor will notify the accredited METC without undue delay of a temporary halt including the reason for such an action. The study will be suspended pending a further positive decision by the accredited METC. The investigator will take care that all subjects are kept informed.

2. Adverse events (AEs) Reporting or recording of adverse events is not applicable in this observational follow up study.

3. The current study is a observational, non-intervention, follow up study in a population that contains patients with possible SAEs as result of their (congenital) heart disease. Therefore, only SAE's resulting from extra blood withdrawals will be reported by the investigator to the sponsor without undue delay after obtaining knowledge of the events.

The sponsor will report the SAEs that are a result of extra blood withdrawal through the web portal ToetsingOnline to the accredited METC that approved the protocol, within 7 days of first knowledge for SAEs that result in death or are life threatening followed by a period of maximum of 8 days to complete the initial preliminary report. All other SAEs, related to extra blood withdrawal, will be reported within a period of maximum 15 days after the sponsor has first knowledge of the serious adverse events.

SAMPLE SIZE CALCULATION: In this study the investigators would like to identify blood-derived biomarkers for right ventricular disease in CHD and PAH. In this sample size calculation the investigators have to take into account all the known references of the to be tested biomarkers and that the levels of the biomarkers could differ with respect to age and gender. Previous research confirmed lower levels of specific biomarkers in children compared to adults. Published results concerns mostly significant results with respect to clinically ill versus clinically adapted patients. The investigators would like to look at the correlation between the level of blood-derived biomarkers and RV function. Based on the published results with respect to biomarkers in CHD, a correlation coefficient of (-)0.3 should be sufficient. TAPSE, gender and age are included as predictor variables. With a good prediction level this will give a sample size of 380.

STATISTICAL ANALYSIS PLAN: For the cross-sectionally primary endpoint, the investigators will analyze the correlations of the level of serum biomarker withRV-function (defined as the echocardiographic measurement TAPSE), using Spearman partial correlation analyses, crude and adjusted for age and sex. Subsequently, linear regression analysis will be used to further explore the relationship between biomarkers with continuous RV function. This will be done at baseline and after one year.

For the exploratory objectives, the stability of biomarkers in time will be assessed using intraclass correlation coefficients.Repeated measures linear mixed model techniques will be applied to explore changes of biomarkers and right ventricular function in time in which patients will be entered as the random component of the mixed model. Binary or multinominal logistic regression analysis will be used to assess the relationship between biomarkers and RV function impairment.

Kaplan Meier and Cox regression analysis will be performed to compare (transplantation-free) survival of patients with high or low baseline biomarkers and to explore the predictive value of biomarkers on clinical outcome.

Not normally distributed continous variables (e.g. biomarkers with skewed distribution) will be, if appropriate, log-transformed, prior to inclusion in the regression models.

Inclusion Criteria:

• Age 0-18 years
• Patients with Pulmonary Arterial hypertension: diagnosis confirmed according to the standards of the National Expertise Center for PH in childhood.
• Patients with CHD with an abnormally loaded right ventricle including tetralogy of Fallot (TOF), pulmonary (valve) stenosis (PS), pulmonary insufficiency (PI), atrial septal defect (ASD), ventricular septal defect (VSD) and total anomalous pulmonary venous return (TAPVR): diagnosis confirmed by echocardiography or cardiac MRI in UMCG-CCH.

Exclusion Criteria:

• Age >18 years
• Not familiar with Dutch language
• Pregnant
• Concomitant musculoskeletal disease
• No echocardiography available within three months before or after blood collection
• Being under examination for non-diagnosed disease at time of investigation

The study population concerns all patients aged 0-18 years with (a history of) an abnormally loaded right ventricle (due to right-sided congenital heart disease or pulmonary arterial hypertension) who visit the outpatient clinic or will be electively admitted at the Center of Congenital Heart Disease - University Medical Center Groningen (CHH-UMCG).