Determinants and Implementation of Hybrid Cardiac Rehabilitation in Adolescents and Young Adults With Congenital Heart Disease: Insight From the QUALIREHAB Study

Abstract

Background

The QUALIREHAB (Cardiac Rehabilitation in Youth With Congenital Heart Disease) trial demonstrated the efficacy of a hybrid cardiac rehabilitation model in adolescents and young adults with congenital heart disease. This post hoc mixed‐methods study aimed to identify baseline predictors of clinical improvement and to characterize key components supporting implementation and scalability.

Methods

Seventy participants aged 13 to 25 years from the intervention arm were analyzed. Clinical improvement was defined as a clinically meaningful increase in cardiopulmonary fitness (increase in peak oxygen uptake ≥3.5 mL/kg per min) or health‐related quality of life (Pediatric Quality of Life Inventory increase ≥4.3 points). Multivariable logistic regression models identified predictors of clinical improvement. Semistructured interviews with patients and health care professionals explored experiences, barriers, and implementation mechanisms.

Results

The absence of prior cardiac surgery or interventional catheterization was independently associated with short‐term improvement in peak oxygen uptake. At 1 year, male sex and lower baseline ventilatory anaerobic threshold were associated with greater peak oxygen uptake improvement. Lower baseline ventilatory anaerobic threshold was also the only predictor of clinically meaningful health‐related quality of life improvement. Qualitative findings highlighted the accessibility and acceptability of the hybrid model but underscored the need for higher‐intensity and more varied exercise modalities, integrated digital tools, continuous psychological support, family involvement, and structured postrehabilitation follow‐up to sustain long‐term benefits.

Conclusions

Among treated participants, male sex, absence of prior cardiac surgery, and marked baseline deconditioning were associated with greater clinical improvement, supporting a shift from standardized toward tailored cardiac rehabilitation in congenital heart disease. By addressing key logistical and psychosocial barriers, this scalable framework offers a pragmatic model for routine care implementation and may be transferable to other pediatric chronic conditions.

Registration

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03690518.

Nonstandard Abbreviations and Acronyms

APA

adapted physical activity

HRQoL

health‐related quality of life

VAT

ventilatory anaerobic threshold

V̇O₂peak

peak oxygen uptake

Clinical Perspective.

What Is New?

• This mixed‐methods analysis suggests early hybrid cardiac rehabilitation in youth with congenital heart disease was associated with greater improvement among male patients, nonsurgical patients, and individuals with marked baseline deconditioning, and qualitative insights further highlight that optimizing rehabilitation adherence may require unified digital platforms, higher‐intensity exercise modalities, and continuous psychosocial support.

What Are the Clinical Implications?

• Cardiac rehabilitation programs for adolescents and young adults with congenital heart disease may benefit from moving beyond standardized models toward tailored, developmentally informed frameworks that prioritize early intervention for deconditioned patients, adapt exercise intensity, and incorporate structured postrehabilitation follow‐up to support long‐term cardiovascular health.

Cardiac rehabilitation has been shown to reduce morbidity and improve health‐related quality of life (HRQoL) in adults with cardiovascular disease, including ischemic heart disease and heart failure. ¹ In recent years, similar approaches have been increasingly proposed for adolescents and young adults with congenital heart disease (CHD), a population facing early cardiovascular risk, reduced exercise capacity, and long‐term psychosocial burden. ² , ³ In this context, home‐based and tele‐health supported cardiac rehabilitation models have been developed to improve accessibility and reduce logistical barriers. ⁴ , ⁵ However, in CHD, home‐based telerehabilitation models used in isolation have generally produced limited benefits, ⁶ , ⁷ largely because they rely on digital or remote formats without sustained human supervision—thereby limiting personalization, multidisciplinary care, and structured supervision, all of which are core components of center‐based cardiac rehabilitation.

Despite major advances in CHD treatment, ⁸ children and adolescents continue to exhibit accelerated declines in peak oxygen uptake (V̇O₂peak) and ventilatory anaerobic threshold (VAT), 2 markers of cardiopulmonary fitness strongly associated with physical function and HRQoL. ⁹ , ¹⁰ , ¹¹ Although physical activity interventions have shown some benefits in young people with CHD², the use of multidisciplinary approaches in cardiac rehabilitation remains scarce. Additionally, empowering transition‐education approaches ¹² , ¹³ , ¹⁴ , ¹⁵ are rarely integrated in cardiac rehabilitation models. As a result, physical activity levels in this population are predominantly driven by psychosocial determinants rather than by disease‐specific limitations. ¹⁶

The QUALIREHAB (Cardiac Rehabilitation in Youth With Congenital Heart Disease) multicenter randomized controlled trial (RCT) addressed gaps in the current standard of care using an early hybrid cardiac rehabilitation model for adolescents and young adults with CHD‐related cardiopulmonary impairment. ¹⁷ QUALIREHAB's originality lies in the integration of both center‐based and home‐based components, and of both in‐person and remote/telerehabilitation formats, within a unified multidisciplinary framework. The 12‐week program began with a 1‐week in‐center phase including cardiovascular evaluation, structured exercise training, disease‐specific and nutritional education, and individualized psychosocial support. The in‐center phase was followed by an 11‐week home‐based phase integrating 2 supervised adapted physical activity (APA) sessions per week alternating between in‐person and remote formats, complemented by monthly in‐center reinforcement visits. ¹⁸ QUALIREHAB's hybrid model enabled the continuity of multidisciplinary care while maximizing accessibility, personalization, and adherence.

Although the QUALIREHAB intervention was proven effective in improving physical health, mental health, and HRQoL, specific determinants of its clinical improvement remain unknown. Identifying which baseline clinical, functional, psychosocial, or behavioral characteristics are associated with greater clinical improvement is essential to optimize patient selection, tailor exercise prescription, and advance toward tailored cardiac rehabilitation in CHD. Moreover, detailed descriptions of cardiac rehabilitation interventions are often insufficient in published trials, hindering replication and real‐world implementation. Given QUALIREHAB's innovative hybrid design, a comprehensive characterization of its structure, components, and delivery is warranted.

This post hoc mixed‐methods study identified parameters associated with greater clinical improvement among participants receiving the QUALIREHAB intervention and provided detailed descriptions of the intervention to support replicability and clinical translation.

METHODS

Data Availability Statement

The data underlying this article are available in the article and in its online supplementary material. Additional de‐identified participant data from the QUALIREHAB trial will be shared on reasonable request to the corresponding author, subject to institutional agreements.

Study Design

Data from the QUALIREHAB multicenter RCT were used for post hoc analysis. The parent RCT enrolled 142 participants aged 13 to 25 years across 12 CHD and 9 cardiac rehabilitation centers in France, with 1:1 randomization to the intervention or usual care. The QUALIREHAB trial was conducted in accordance with the Declaration of Helsinki. The study protocol was approved by the relevant French National Ethics Committee. Written informed consent was obtained from all participants and their legal guardians before inclusion in the study (ClinicalTrials.gov Identifier: NCT03690518).

The program relied on a comprehensive multidisciplinary team. This included pediatric and adult CHD cardiologists, cardiopulmonary exercise test physician and technician, APA educator, physiotherapist, specialist nurse, dietitian, psychologist, and social worker.

The primary outcome of the RCT was change in self‐reported HRQoL (Pediatric Quality of Life Inventory [PedsQL] total score ¹⁹ , ²⁰ , ²¹ ) from baseline to 12‐month follow‐up. Secondary endpoints included cardiovascular parameters, cardiopulmonary fitness, ⁹ physical activity levels, ²² mental health, ²³ , ²⁴ , ²⁵ and disease‐knowledge outcomes. ²⁶ , ²⁷ The intervention was shown to be safe, well accepted, and associated with significant improvements in body mass index, HRQoL, physical activity, disease knowledge, and short‐term cardiopulmonary fitness. ¹⁷

For the present analysis, detailed quantitative data were extracted from the electronic case report forms and medical records only for participants randomized to the QUALIREHAB intervention group, with the aim of identifying baseline parameters associated with greater clinical improvement of the rehabilitation program. Clinical improvement was defined a priori using clinically meaningful thresholds and evaluated at 2 time points reflecting short‐term and long‐term effects of the intervention. Short‐term clinical improvement corresponded to outcomes assessed immediately after completion of the 12‐week cardiac rehabilitation program, whereas long‐term clinical improvement was assessed at 12 months after inclusion. Specifically, clinical improvement was defined as either (1) an increase ≥3.5 mL/kg/min in V̇O₂peak at 3 or 12 months, corresponding to the recognized population‐based prognostic cutoff of ∼1 metabolic equivalent of task, ²⁸ , ²⁹ or (2) an improvement ≥4.3 points in the self‐reported PedsQL total score at 12 months, corresponding to the established minimal clinically important difference for the PedsQL questionnaire. ²¹

In parallel, a qualitative evaluation was performed through semi‐structured interviews with healthcare professionals involved in program delivery and patients who completed the intervention. These interviews explored perceived benefits, barriers, adherence dynamics, and suggestions for optimization, providing complementary insight into the implementation and real‐world functioning of the hybrid cardiac rehabilitation model.

Population

Quantitative Component

This post hoc analysis only included participants randomized to the QUALIREHAB intervention arm of the parent multicenter RCT. Of the 72 participants allocated to the intervention, 70 completed baseline assessments and were included in the present analysis. As per the original protocol, eligible participants were adolescents or young adults aged 13 to 25 years with CHD and impaired cardiopulmonary fitness, defined as V̇O₂peak<80% predicted or VAT < 55% predicted. ¹⁷

Exclusion criteria in the parent trial included absolute contraindications to cardiopulmonary exercise test, planned cardiac surgery during the study period, prior cardiac rehabilitation within the previous 2 years, uncontrolled heart failure or arrhythmia, severe left ventricular outflow tract obstruction, pregnancy, or inability to complete the self‐reported PedsQL questionnaire. Patients were recruited consecutively during outpatient visits.

Qualitative Component

Within the qualitative segment, semi‐structured interviews (Data S1—Interview Guide) were conducted with 10 healthcare professionals directly involved in delivering the intervention (including pediatric cardiologists, specialist nurses, exercise training professionals, and psychologists) and 11 patients who had fully completed the QUALIREHAB program. Participants were selected using purposive sampling to capture a diversity in professional roles and patient experiences within the hybrid cardiac rehabilitation pathway.

Delivered Components of the QUALIREHAB Intervention

Center‐Based Initiation Week

During week 1, participants underwent a structured program including:

• Cardiovascular assessments: pediatric cardiology consultation, physical examination, ECG, echocardiography, spirometry, and cardiopulmonary exercise test at the beginning of the week.

• Exercise training:

  • ◦
    Group APA sessions combining moderate‐intensity interval training (targeting the heart rate corresponding to the VAT) performed on a stationary bicycle, together with varied and enjoyable activities (boxing, dance, Pilates, ball games, etc.).
  • ◦
    Individual physiotherapy focusing on breathing techniques, posture, and isometric strengthening.

• Patient education: individualized assessments and educational workshops covering CHD knowledge, risk prevention, benefits and limitations of physical activity, and self‐monitoring of heart rate and symptoms.

• Nutritional counseling: an individual consultation and a group workshop on balanced diet and meal composition.

• Psychosocial care: psychological evaluation and access to social support when needed.

• At the end of the initiation week, the rehabilitation cardiologist reviewed progress and delivered a personalized home‐based exercise prescription.

Home‐Based Phase

During the 11‐week home phase (from week 2 to 12), patients completed 2 supervised APA sessions per week, alternating between in‐person and videoconference formats. Sessions followed an interval training structure at moderate intensity and incorporated motivational guidance to support adherence. Educational follow‐up continued as needed.

Reinforcement Visits

Three reinforcement visits took place at weeks 4, 8, and 12. Each included:

• Pediatric cardiology follow‐up (clinical evaluation, safety monitoring, and adherence review)

• Group APA sessions at moderate intensity

• Individual physiotherapy sessions

• Tailored educational refreshers based on patient needs

Statistical Analysis

Both quantitative and qualitative analyses were performed.

Quantitative Analysis

Baseline characteristics were summarized using means±SD for continuous variables, and frequencies and percentages for categorical variables. The primary aim was to identify baseline predictors of clinical improvement. Given the sample size, predictors of the clinical improvement (clinical, functional, psychosocial, and behavioral variables) were investigated with firth penalized multiple logistic regression model and odds ratio (OR) with their 95% CIs were reported. All clinically relevant parameters with a P<0.20 in the univariate analyses were selected for multivariable analysis, and a backward covariate selection procedure with an output threshold at 0.10 was performed. Model performance was evaluated using the area under the receiver operating characteristic curve. Statistical significance was set at P < 0.05, and analyses were performed using SAS 9.04 (SAS Institute, Cary, NC, USA).

Qualitative Analysis

Qualitative data were collected through semistructured interviews (Data S1—Interview Guide) with 11 patients (aged 14 to 24 years) and 10 health care professionals. Participants were selected using purposive sampling to capture a diversity of perspectives regarding the hybrid rehabilitation program. As interviews were not audio‐recorded, comprehensive field notes were taken by the investigator during and immediately after each session to capture key insights and verbatim quotes. This approach was chosen to facilitate participant comfort and open discussion, particularly among adolescents. The analysis followed a thematic analysis approach. Two investigators independently reviewed the field notes and performed inductive coding to identify recurrent ideas. Codes were first grouped into thematic domains reflecting recurring experiential dimensions of the rehabilitation program. These domains were subsequently synthesized into 3 overarching themes to facilitate interpretation and clinical translation of the qualitative findings (Data S2—Codebook). Discrepancies were resolved through discussion until consensus was reached. To enhance analytical rigor, the coding framework was iteratively refined through discussion between the investigators and continuously compared with incoming interview data to ensure internal consistency of the thematic structure.

Data saturation was assessed by monitoring the emergence of new codes across interviews. As detailed in Table S1, a stable coding structure was reached after the fifth patient interview, after which the subsequent 6 interviews yielded no additional codes and served to confirm the thematic framework.

Finally, patient perspectives were triangulated with professionals' insights to ensure a comprehensive understanding of the program's strengths and limitations. This triangulation helped confirm the consistency and robustness of the identified thematic domains (Table S2).

RESULTS

Population Characteristics

A total of 70 participants from the intervention arm were included in this post hoc analysis. The mean age was 17.1±3.5 years, and 46% were male. Most participants were in middle or high school and lived with their parents. CHD complexity was heterogeneous, with representation from simple, moderate, and complex defects, including 13% with single‐ventricle physiology. Half of the cohort had undergone 1 prior cardiac surgery, and 30% had undergone ≥2.

Baseline cardiopulmonary fitness was impaired, with a mean V̇O₂peak of 27.3±5.9 mL/kg/min (≈70% predicted) and a mean percentage‐predicted VAT of 45%±10.7%. Mental health scores showed mild to moderate levels of anxiety and depression. Overall, disease knowledge and physical activity levels were low to moderate. Additional details on demographic, clinical, functional, and psychosocial characteristics are presented in Table 1.

Table 1.

Baseline Population Characteristics

	Cardiac rehabilitation group (N=70)
Sociodemographic characteristics
Age, y	17.1±3.5
Male sex, no. (%)	32 (46)
Level of education, no. (%)
Middle school	33/69 (48)
High school	26/69 (38)
University	10/69 (14)
Living environment, no. (%)
Living alone	5 (7)
Living as a couple	6 (9)
Living with parent(s)	53 (76)
Other	6 (9)
Cardiovascular outcomes
Body mass index, kg/m2	21.8±3.6
Resting heart rate, bpm	84.8±18.6
Resting blood pressure, mm Hg
Resting systolic blood pressure	119.5±17.4
Resting diastolic blood pressure	68.6±12.3
New York Heart Association functional class, no. (%)
I	35/63 (55)
II	27/63 (43)
III	1/63 (2)
Type of congenital heart disease, no. (%)
Transposition of the great arteries	5/69 (7)
Atrial septal defect	9/69 (13)
Ventricular septal defect	12/69 (17)
Conotruncal defect	14/69 (21)
Aortic valve disease	5/69 (7)
Pulmonary valve disease	2/69 (3)
Coarctation of the aorta	8/69 (12)
Univentricular heart disease	9/69 (13)
Atrioventricular septal defect	2/69 (3)
Other	3/69 (4)
Cardiac surgeries, no. (%)
0	13/69 (19)
1	35/69 (51)
≥2	21/69 (30)
Interventional cardiac catheterization, no. (%)
0	46/69 (67)
1	15/69 (22)
≥2	8/69 (11)
Pacemaker, no. (%)	3 (4)
Mechanical valve, no. (%)	3 (4)
Patient receiving cardiac medications, no. (%)	20 (29)
Cardiovascular comorbidity, no. (%)
Thromboembolic event	1 (1)
Arrhythmia	12 (17)
Genetic anomalies, no. (%)	3 (4)
Other comorbidities, no. (%)	6 (9)
Echocardiography, %
Systemic ventricular ejection fraction	61.9±8.7
Health‐related quality of life
PedsQL self‐reported scores (range 0–100)
Total score	71.6±15.2
Physical functioning	73.5±18.8
Psychosocial health summary score	70.8±15.4
Emotional functioning	67.0±22.9
Social functioning	78.6±18.9
School functioning	66.6±17.5
PedsQL proxy‐reported scores (range 0–100)
Total score	67.9±17.5
Physical functioning	73.6±20.9
Psychosocial health summary score	65.2±18.5
Emotional functioning	62.1±23.3
Social functioning	73.0±24.7
School functioning	60.8±19.2
Leuven Knowledge Questionnaire for Congenital Heart Disease (range 0–100)
Total score	21.1±6.4
Physical health outcomes
Level of physical activity (range 9–45)
Total score	20.8±7.0
Spirometry parameters
FEV1, L	2.8±0.9
FEV1, Z‐score	−1.2±1.5
FVC, L	3.3±1.1
FVC, Z‐score	−1.3±1.9
FEV1/FVC, %	85.0±9.5
FEV1/FVC, Z‐score	0.9±2.8
Cardiopulmonary exercise test parameters
Submaximal parameters
VAT, mL/kg/min	17.6±3.8
VAT, % predicted	45.0±10.7
Heart rate at VAT, bpm	128.6±20.2
Workload at VAT, Watts	73.5±28.4
Ventilatory efficiency slope	32.2±6.9
Maximal parameters
V̇O2peak, mL/kg/min	27.3±5.9
V̇O2peak, % predicted	69.5±10.6
Maximum heart rate, bpm	172.0±22.4
Maximum workload, Watts	127.7±43.7
Maximum oxygen pulse, mL/beat	9.48±2.83
Maximum respiratory exchange ratio	1.25±0.16
Mental health outcomes
Anxiety symptoms in adolescents (STAI‐Children) (range 20–60)*
Total score	31.9±6.9
Anxiety symptoms in young adults (STAI) (range 20–80)*
Total score	44.2±13.5
Depression symptoms in adolescents (child depression inventory) (range 0–54)†
Total score	10.4±6.3
Depression symptoms in young adults (Beck depression inventory) (range 0–63)†
Total score	5.9±5.9

Values are N (%), n/N (%), or mean±SD. FEV₁ indicates forced expiratory volume in 1 second; FVC, forced vital capacity; PedsQL, Pediatric Quality of Life Inventory; STAI, state and trait anxiety inventory; VAT, ventilatory anaerobic threshold; and V̇O₂peak, peak oxygen uptake.

^*Higher score indicates a higher level of anxiety symptoms.

^† Higher score indicates a higher level of depression symptoms.

Predictors of Clinical Improvement

In the population 39% had an increase ≥3.5 mL/kg per min in V̇O₂peak at follow‐up immediately after completion of the cardiac rehabilitation program (3 months), 29% had an increase ≥3.5 mL/kg/min in V̇O₂peak at long‐term follow‐up (12 months), and 52% had a clinically meaningful increase (≥4.3 points) in the self‐reported PedsQL total score at long‐term follow‐up (12 months).

Parameters Associated With Short‐Term and Long‐Term Improvement in Cardiopulmonary Fitness

In univariate analyses, the absence of previous cardiac surgery and, as a distinct independent variable, the absence of prior interventional catheterization were associated with an increase ≥3.5 mL/kg/min in V̇O₂peak at follow‐up immediately after completion of the cardiac rehabilitation program (3 months). In multivariable analysis, both variables remained independently associated with short‐term improvement in cardiopulmonary fitness.

At long‐term follow‐up (12 months), different determinants emerged. Male sex and a lower baseline percentage‐predicted VAT were independently associated with a clinically relevant increase in V̇O₂peak. These associations were consistent across univariate and multivariable models.

Parameters Associated With Long‐Term Improvement in HRQoL

A lower baseline VAT was the only parameter independently associated with a clinically meaningful increase (≥4.3 points) in the self‐reported PedsQL total score at long‐term follow‐up (12 months).

Detailed ORs, CIs, and model performance metrics are presented in Table 2.

Table 2.

Parameters Associated With the Clinical Improvement

	Change in V̇O2peak at 3 mo ≥3.5 mL/kg/min		Change in V̇O2peak at 1 year ≥3.5 mL/kg/min		Change in total HRQoL score at 1 year ≥4.3 points
	Univariate analysis	Multivariable analysis (N=48)*	Univariate analysis	Multivariable analysis (N=43)*	Univariate analysis	Multivariable analysis (N=60)*
	OR crude (95% CI)	OR adjusted (95% CI)	OR crude (95% CI)	OR adjusted (95% CI)	OR crude (95% CI)	OR adjusted (95% CI)
Age	1.01 (0.84–1.21)		0.96 (0.81–1.13)		1.08 (0.93–1.25)
Sex
Male	0.90 (0.29–2.85)		3.13 (1.00–9.76)	5.70 (1.26–25.92)	0.65 (0.24–1.78)
Female	…		…	…	…
Cardiac surgery
No	10.23 (1.37–76.53)	14.83 (1.47–150.03)	1.94 (0.54–7.03)		0.92 (0.26–3.27)
Yes	…	…	…		…
Interventional cardiac catheterization
No	5.09 (1.08–24.03)	7.18 (1.12–46.04)	1.27 (0.39–4.19)		0.63 (0.22–2.12)
Yes	…	…	…		…
Cardiac medications
No	2.78 (0.68–11.34)	…	1.64 (0.47–5.71)		0.83 (0.26–2.60)
Yes	…		…		…
Body mass index, kg/m2	0.99 (0.83–1.17)		0.90 (0.77–1.06)	…	1.00 (0.86–1.15)
Resting diastolic blood pressure, mm Hg	1.03 (0.98–1.09)		1.05 (0.99–1.11)	…	1.03 (0.99–1.08)	…
Resting heart rate, bpm	0.98 (0.94–1.01)	…	1.01 (0.98–1.04)		1.01 (0.98–1.04)
V̇O2peak, mL/kg/min	Not entered in the model†		Not entered in the model†		0.92 (0.84–1.01)	…
VAT, mL/kg/min	0.91 (0.76–1.09)		0.95 (0.82–1.11)		0.84 (0.72–0.98)	0.84 (0.72–0.98)
VAT, % predict	0.97 (0.91–1.04)		0.92 (0.85–1.00)	0.91 (0.81–1.03)	0.95 (0.89–1.01)
Ventilatory efficiency slope	0.94 (0.85–1.03)	…	0.94 (0.86–1.03)	…	1.03 (0.95–1.11)
Area under the curve (95% CI)		0.79 (0.70–0.89)		0.83 (0.71–0.96)		0.69 (0.55–0.82)

HRQoL indicates health‐related quality of life; OR, odds ratio; VAT, ventilatory anaerobic threshold; and V̇O₂peak, peak oxygen uptake.

^*Analysis of complete data

^† Part of the outcome definition.

Intervention Delivery and Adherence

The complete study protocol is detailed in the Methods section, and Table 3 reports the actual delivery of the hybrid center‐ and home‐based program. It compares the number of sessions completed by participants with those initially prescribed for the intervention components that were quantitatively tracked. Overall, adherence to the program was high. Most components of the center‐based initiation week, including cardiovascular assessments and follow‐up consultations, were completed in nearly all participants. Adherence to exercise sessions ranged from 85% to 92%, and participation in other multidisciplinary components such as physiotherapy, education, nutritional counseling, and psychological support ranged from 64% to 93%. These findings support the real‐world feasibility and deliverability of the hybrid QUALIREHAB intervention.

Table 3.

Delivery and Adherence to the QUALIREHAB Hybrid Cardiac Rehabilitation Program

Components		Contexts (center based/home based; in person/videoconference; individual/group)	Multidisciplinary team	Contents	Completed sessions	Adherence (%)
Center‐based cardiac rehabilitation: initiation wk
Initial cardiovascular assessments	Cardiology consultation	Center based; in person; individual	Pediatric cardiologist or adult congenital cardiologist	Clinical examination, ECG, verification of patient eligibility, program prescription (30 min)	1±0 (of 1 prescribed)	100%
	Echocardiography	Center based; in person; individual	Pediatric cardiologist or adult congenital cardiologist	Echocardiography (20 min)	1±0 (of 1 prescribed)	100%
	Spirometry and CPET	Center based; in person; individual	CPET physician and technician	Spirometry and CPET (40 min)	1±0 (of 1 prescribed)	100%
Exercise training	APA	Center based; in person; group	APA educator or physiotherapist	Moderate‐intensity interval training using a stationary bicycle and various physical activities (boxing, dancing, Pilates, ball games, etc.) (1 h per session)	7.86±1.77 (of 9 prescribed)	87%
	Physiotherapy	Center based; in person; individual	Physiotherapist	Breathing work, postural work, isometric muscle strengthening (1 h per session)	2.79±1.25 (of 3 prescribed)	93%
Patient education	Educational assessment	Center based; in person; individual	Specialist nurse	Interview to know the patient's daily life (1 h)	3.41±1.55 (of 5 prescribed)	68%
			Specialist nurse	Synthesis (1 h)
	Disease‐specific patient education	Center based; in‐person; individual or group	Specialist nurse, pediatric cardiologist, adult congenital cardiologist, APA educator	Three workshops on: knowledge of the congenital heart disease, risk prevention (endocarditis, etc), benefits and obstacles of physical activity, education in self‐monitoring of heart rate, symptoms, and perceived exertion (1 h per session)
	Nutritional counseling	Center based; in person; individual	Dietitian	Interview to assess the patient's energy needs, and explain the balanced diet (1 h)	1.27±0.58 (of 2 prescribed)	64%
		Center based; in person; group	Dietitian	Workshop on dietary composition of meals, and food knowledge (1 h)
Psychosocial care	Mental health support	Center based; in person; individual	Psychologist	Interview to assess the patient's psychological status and provide tailored support (1 h)	0.90±0.35 (of 1 prescribed)	90%
	Social support	Center based; in person; individual	Social worker	Interview to assess the patient's social environment and suggest solutions to the patient's social problems (1 h)	Support provided upon patient request
Final cardiovascular assessments	Cardiology consultation	Center based; in person; individual	Pediatric cardiologist or adult congenital cardiologist	Global synthesis, feedback from the week, home‐based program prescription (30 min)	1±0 (of 1 prescribed)	100%
Home‐based cardiac rehabilitation: wk 2–12
Exercise training	APA	Home based; in person or videoconference (alternation); individual	APA educator	Moderate‐intensity interval training using a stationary bicycle and motivational interviewing (1 h per session, 2 sessions per wk)	20.25±3.65 (of 22 prescribed)	92%
Center‐based cardiac rehabilitation: three reinforcement sessions
Cardiological control	Cardiology consultation	Center based; in person; individual	Pediatric cardiologist or adult congenital cardiologist	Clinical examination, checking safety, assessing adherence to the program (30 min per consultation)	3±0 (of 3 prescribed)	100%
Exercise training	APA	Center based; in person; group	APA educator or physiotherapist	Moderate‐intensity interval training exercise using a stationary bicycle (1 h per session)	2.56±0.85 (of 3 prescribed)	85%
	Physiotherapy	Center based; in person; individual	Physiotherapist	Lower‐limb stretching, breathing exercises, and isometric muscle strengthening (1 h per session)	1.94±1.19 (of 3 prescribed)	65%
Patient education	Disease‐specific patient education	Center based; in person; individual or group	Specialist nurse	Review of knowledge and topics identical to those covered in the initiation week (according to the patient's needs) (1 h per session)	2.18±1.19 (of 3 prescribed)	73%

Values are mean±SD of completed sessions compared with the number of sessions initially prescribed in the intervention protocol. Adherence (%) was calculated as the ratio of completed sessions to prescribed sessions. APA indicates adapted physical activity; CPET, cardiopulmonary exercise test; and QUALIREHAB, Cardiac Rehabilitation in Youth With Congenital Heart Disease.

Experiences and Perceptions of Participants and Professionals (Qualitative Findings)

Qualitative analysis identified 8 thematic domains describing participants' and professionals' experiences with the QUALIREHAB program. These domains were subsequently organized into 3 overarching themes reflecting the program's perceived strengths, its impact on well‐being, and the barriers and improvement needs identified during implementation. The final 6 patient interviews yielded no additional codes and provided confirmatory insights, supporting thematic saturation and strong convergence between patient and professional perspectives (Tables S1 and S2).

Main Theme 1: Perceived Strengths

Both professionals and patients emphasized that the hybrid structure, combining an intensive center‐based initiation week with remotely supervised home sessions, enhanced intervention accessibility and flexibility while maintaining regular contact with the multidisciplinary team. The continuity of supervision was perceived as a key facilitator of adherence, motivation, and safety. Professionals highlighted the value of the multidisciplinary approach, which allowed simultaneous attention to physical, educational, psychological, and social needs.

Main Theme 2: Impact on Well‐Being

Patients reported improvements in physical capacity, confidence, and well‐being. They particularly appreciated the supportive environment during the initiation week and the personalized guidance throughout the home‐based phase. Psychological support was considered a major strength, helping participants manage stress, fears, and emotional challenges related to CHD and exercise.

Main Theme 3: Barriers and Improvement Needs

Several structural and operational limitations of the QUALIREHAB program were highlighted through the interviews. These findings were organized into several subthemes reflecting participants' and professionals' suggestions for program optimization.

• Exercise sessions: professionals and patients agreed that interval training at moderate intensity was safe but often insufficiently challenging for many participants. During the home‐based phase, 1‐hour sessions on the stationary bicycle were frequently described as too long or monotonous, with a need for varied playful exercise modalities that better match adolescents' preferences and motivation.

• Session format and content: participants expressed a need for greater diversity and personalization in both exercise and educational components. Group educational sessions were particularly valued, as they fostered peer connection and reduced feelings of isolation.

However, several participants found that some educational content was overly medicalized or even stigmatizing when too strongly centered on disease, symptoms, or restrictions. These themes were sometimes perceived as anxiety provoking or disconnected from adolescents' developmental needs and identity‐building. In contrast, future‐oriented and empowering topics, such as sports participation, autonomy in daily life, or future pregnancy, were described as more relevant, optimistic, and motivating. Health care providers recognized the importance of tailoring educational content to developmental stage, health literacy, and psychosocial context, with greater emphasis on strengths, possibilities (sports participation), and long‐term life goals rather than limitations.

• Program logistics: attendance at reinforcement visits was occasionally limited by scheduling constraints, school commitments, and transportation challenges. Patients suggested alternative formats, such as remote reinforcement sessions or more flexible scheduling, to reduce logistical burden.

• Digital tools and the need for a single integrated platform: patients and professionals noted that the program's digital environment was fragmented across separate systems for scheduling, videoconferencing, documentation, and education. This lack of integration reduced usability and weakened coordination between the center‐ and home‐based phases. Participants consistently called for a single, unified digital platform centralizing all functions: clinical follow‐up, scheduling, remote sessions, secure messaging, educational modules, self‐monitoring tools, and tailored interfaces for children, adolescents, parents, and health care professionals. The absence of such an integrated tool was identified as one of the most important limitations of the original program.

• Psychological support: although psychological assessment was included during the initiation week, ongoing psychological support was not integrated into the home‐based phase and was available only on request during reinforcement visits. Participants and professionals stressed the need for a dedicated and continuous psychological component throughout the 12‐week program, integrated into the routine follow‐up to address anxiety, motivation, self‐image, and treatment adherence.

• Postrehabilitation follow‐up: patients and professionals highlighted the lack of structured support after completion of the 12‐week intervention. Many reported a need for continued guidance to maintain exercise habits, consolidate psychological gains, and sustain educational progress. Suggested options included booster sessions, periodic teleconsultations, or a digital follow‐up pathway integrated into the future unified platform.

• Family involvement: several patients emphasized the importance of involving parents or relatives more actively, both to support adherence at home and to reinforce understanding of exercise recommendations, CHD‐specific risks, and motivational strategies.

Overall Synthesis of Qualitative Findings

Overall, the qualitative findings indicate that the QUALIREHAB hybrid rehabilitation program was perceived as feasible, supportive, and beneficial by both patients and health care professionals. Participants highlighted its multidimensional impact on physical capacity, motivation, emotional well‐being, and disease understanding. At the same time, the interviews identified several opportunities for improvement, including greater personalization of exercise modalities, enhanced digital support, continuous psychological support throughout the program, structured postrehabilitation follow‐up, and more active involvement of families in supporting long‐term behavioral change.

DISCUSSION

This post hoc mixed‐methods analysis provides new insights into both the factors associated with clinical improvement and the implementation mechanisms potentially underlying the observed benefits of a hybrid cardiac rehabilitation model in adolescents and young adults with CHD. By integrating quantitative predictors with qualitative implementation data, this study clarifies which baseline characteristics were associated with greater clinical improvement among treated participants, while also providing insight into how and why this hybrid model may function in real‐world settings.

From a physiological perspective, the absence of prior cardiac surgery or interventional catheterization was strongly associated with short‐term improvement in V̇O₂peak, likely reflecting a predominance of reversible peripheral deconditioning rather than fixed central hemodynamic limitation. ³⁰ , ³¹ In contrast, patients with complex surgical histories may exhibit lower clinical improvement following conventional moderate‐intensity exercise training, underscoring the need for adapted rather than exclusionary strategies in this population. ³² , ³³

Beyond disease complexity, individual characteristics were associated with long‐term clinical improvement. Male sex was independently associated with greater V̇O₂peak improvement at 12 months follow‐up, consistent with known sex‐related differences in body composition, oxygen‐carrying capacity, and physical activity during adolescence. ¹⁶ , ³⁴ , ³⁵ , ³⁶ , ³⁷ These sex‐related differences should not be interpreted as evidence of reduced treatment effect in female patients but rather as an opportunity to tailor motivational, psychosocial, and training strategies across sexes.

A lower baseline VAT emerged as the most robust predictor of improvement in both cardiopulmonary fitness and HRQoL. Beyond the expected statistical phenomenon whereby lower initial values naturally offer a wider margin for physiological adaptation, this finding highlights a clinically meaningful window to tailor exercise training intensity. ³⁸ Markedly reduced VAT in this population often reflects behavioral deconditioning driven by fear of exertion, parental overprotection, and reduced autonomy rather than disease severity alone. ³⁹ , ⁴⁰ These patients may represent an important target population for early, structured, multidisciplinary cardiac rehabilitation programs aimed at addressing reversible functional limitations.

Qualitative findings helped contextualize these quantitative results. Continuous supervision and regular contact with the multidisciplinary team were perceived as key drivers of adherence, safety, and motivation, particularly during the transition from center‐based to home‐based phases. At the same time, participants consistently reported that 1‐hour moderate‐intensity cycling sessions were sometimes monotonous and insufficiently challenging. These observations align with quantitative findings suggesting that participants with higher baseline fitness showed less observed improvement from moderate‐intensity training alone, supporting the exploration of more adaptable intensity strategies such as higher‐intensity interval training. This type of training is already used in adult cardiac rehabilitation ⁴¹ , ⁴² , ⁴³ , ⁴⁴ , ⁴⁵ and would require careful adaptation for populations with CHD.

Broader psychosocial and structural factors also influenced engagement. Educational content perceived as overly disease centered could be experienced as stigmatizing, whereas future‐oriented topics related to autonomy and life goals were more motivating. Fragmented digital tools and limited continuity of psychological support were identified as barriers, highlighting the need for integrated platforms and sustained psychosocial care to support long‐term behavior change. These findings are particularly relevant given the high prevalence of mental health and neurodevelopmental challenges in adolescents and young adults with CHD. ⁴⁶ , ⁴⁷ , ⁴⁸

Overall, the QUALIREHAB model illustrates how hybrid cardiac rehabilitation programs can expand access while preserving core components of effective care, notably human supervision, multidisciplinary coordination, and individualized support. From a public health and preventive cardiology perspective, successful scale‐up of pediatric and congenital hybrid cardiac rehabilitation will likely require dedicated reimbursement pathways, investment in integrated digital infrastructures, and close collaboration between hospital‐based teams, community providers, families, and patient advocacy organizations.

Regarding transferability, the QUALIREHAB program was implemented within a national multicenter network including tertiary CHD and cardiac rehabilitation centers. Its hybrid structure—combining a short center‐based initiation phase with supervised home‐based sessions and periodic reinforcement visits—may therefore be applicable to other structured cardiac rehabilitation settings. However, implementation remains context‐dependent and requires organizational capacity for home visits or telehealth as well as sustainable reimbursement pathways for the home‐based components. At the same time, the home‐based component of the hybrid model may also promote more equitable access to cardiac rehabilitation by reducing travel requirements and facilitating participation for patients living far from specialized centers or facing academic or professional constraints.

Several limitations should be acknowledged. Because this post hoc analysis was restricted to the intervention arm, these findings should be interpreted as factors associated with clinical improvement among treated participants rather than formal predictors of differential treatment efficacy across subgroups. Behavioral and socioeconomic variables were not comprehensively assessed at baseline, limiting exploration of their contribution to cardiac rehabilitation responsiveness. Physical activity relied on self‐reported measures rather than objective monitoring, which may have introduced recall bias. In addition, HRQoL was not assessed immediately after the intensive home‐based phase, precluding evaluation of short‐term psychosocial trajectories relative to changes in cardiopulmonary fitness. Finally, regarding the qualitative analysis, interviews were based on detailed field notes rather than audio recordings, which may have limited the granularity of verbatim data. Although the overall trial was multicenter, the qualitative component relied on a purposive and relatively small sample, which may introduce selection bias. We also acknowledge that potential researcher influence during qualitative data collection and thematic coding is an inherent limitation of this approach.

Conclusions

In conclusion, this study supports a shift from standardized cardiac rehabilitation toward tailored, developmentally informed, and implementation‐ready cardiac rehabilitation in CHD. By combining physiological profiling with detailed intervention description and patient‐ and provider‐derived implementation insights, QUALIREHAB offers a potential scalable hybrid framework that bridges efficacy and real‐world feasibility. These findings also provide a coherent rationale for the evolution of more holistic cardiac rehabilitation strategies designed to address the full spectrum of functional, psychosocial, and developmental needs in young people living with CHD.

APPENDIX

The QUALIREHAB Study Group

Sophie Guillaumont (Montpellier University Hospital, France); Omar Oubari (Anamnese, France); Jerome Bourreau (Anamnese, France); Johanna Calderon (INSERM 1163 Imagine Institute, France, https://orcid.org/0000‐0002‐2644‐6858); Stephane Moniotte (University Hospitals Saint‐Luc Brussels, Belgium, https://orcid.org/0000‐0002‐0900‐6674); Jelena Hubrechts (University Hospitals Saint‐Luc Brussels, Belgium, https://orcid.org/0000‐0001‐6719‐2746); Esteban Peiró‐Molina (IIS La Fe Valencia, Spain, https://orcid.org/0000‐0002‐7177‐0171); Erika Rezola (IIS Biogipuzkoa Donostia/San Sebastian, Spain, https://orcid.org/0000‐0001‐5197‐6618); Begoña Manso (Hospital Universitario Virgen del Rocío Sevilla, Spain, https://orcid.org/0000‐0002‐3776‐8860); Gonzalo Oñoro (Gerencia de Atencion Primaria Salud Madrid, Spain); Francisco‐José Ferrer‐Sargues (Universidad Cardenal Herrera CEU, Spain, https://orcid.org/0000‐0001‐9016‐5543); Alice Bordessoule (Geneva University Hospital, Switzerland, https://orcid.org/0000‐0001‐8155‐8433); Arthur Gavotto (Montpellier University Hospital, France, https://orcid.org/0000‐0001‐6485‐7634); Stephan Matecki (Montpellier University Hospital, France, https://orcid.org/0000‐0002‐1878‐0936); Oscar Werner (Nantes University Hospital, France, https://orcid.org/0000‐0002‐3741‐0498); Marion Audie (Bordeaux University Hospital, France); Cecile Jore (Bordeaux University Hospital, France); Mathieu Andrianoely (University of Bordeaux, France); Caroline Neyraud (Bordeaux University Hospital, France, https://orcid.org/0000‐0001‐7142‐7659); Anne‐Cecile Huby (Bordeaux University Hospital, France, https://orcid.org/0009‐0000‐8845‐3861); Marine Tortigue (Lyon University Hospital, France, https://orcid.org/0000‐0002‐2898‐9856); Alyssia Venna (Children's National Hospital Washington DC, USA); Arielle Desir (Children's National Hospital Washington DC, USA); Jared Hershenson (Children's National Hospital Washington DC, USA, https://orcid.org/0009‐0004‐8957‐9561); Mary‐Kate Batterton (Children's National Hospital Washington DC, USA); Justin Burton (Children's National Hospital Washington DC, USA, https://orcid.org/0000‐0002‐5876‐6629); Yves D'Udekem (Children's National Hospital Washington DC, USA, https://orcid.org/0000‐0003‐1851‐7836); Pascal Amedro (Children's National Hospital Washington DC, USA).

Sources of Funding

The original QUALIREHAB trial was supported by public grants from the Direction Generale de l'Offre de Soins (National Health Department, GIRCI SOHO, PHRCI2017‐SOHO‐39). This post hoc study is part of the QUALIREHAB implementation research project, funded in Europe by the “Innovate to Prevent” European Joint Transnational Call (JTC‐THCS 2024) and supported in the United States by institutional funding from the Children's National Hospital Foundation (Dunn Family Endowed Professorship of Cardiac Research, Heart Research Institute).

Disclosures

All authors declare no disclosure of interest for this contribution.

Supporting information

Data S1–S2

Tables S1–S2

GRAMMS reporting checklist