The impact of cardiac rehabilitation on quality of life and 6 minute walk test in post Glenn patients

Ahmed Kadry Abdelhady Araquib, Abdifatah Omar Abubakar Abdelhady, Ahmed Mohamed Abo Bakr El Missiri, and Youssef Mohammed Mohammed Fahmy. The impact of cardiac rehabilitation on quality of life and 6 minute walk test in post Glenn patients. Cardiometry; Issue No. 33; November 2024; p. 8086; DOI: 10.18137/cardiometry.2024.33.8086; Available from:

Congenital heart disease (CHD) ranks among the most common congenital anomalies, affecting between 3.5 and 17.5 per 1,000 live births 1, 2. Over the past two to three decades, advances in both medical care and surgical techniques have led to significant improvements in survival, with over 95% of CHD patients now reaching adulthood 3.

For individuals with single ventricle physiology, also referred to as univentricular heart, a multidisciplinary team of pediatric cardiologists and cardio-thoracic surgeons is required to devise an appropriate treatment plan. This typically involves a series of staged palliative surgeries4. The bidirectional Glenn (BDG) and hemi-Fontan procedures are key surgical approaches aimed at establishing a superior cavo-pulmonary connection, a crucial step in the overall Fontan completion. These operations are performed in patients with a structural or functional single ventricle 5.

Studies from various centers have demonstrated reduced mortality and morbidity in patients undergoing the BDG or hemi-Fontan surgeries as part of the Fontan pathway6-8. However, functional limitations remain a concern for many of these individuals. The decline in functional capacity is not only linked to the surgical intervention but is also compounded by the tendency of parents, teachers, and healthcare providers to overly restrict the physical activity of these patients, contributing to a sedentary lifestyle and reduced exercise tolerance 9, 10.

This study explored the impact of a 12-week cardiac rehabilitation (CR) program on the 6-minute walk test and quality of life (QoL) in individuals who had previously undergone the Glenn shunt procedure.

PATIENTS AND METHODS

Design and population:

This study was a 2-arm parallel, prospective, randomized, controlled trial conducted at Ain Shams University Hospitals. It included 35 patients, both male and female, aged six years and above, who had undergone surgery at least six months earlier. Patients were recruited over a six-month period.

Eligibility criteria

Inclusion criteria required patients to be older than six years and at least six months post-surgery, with the ability to perform a submaximal treadmill exercise stress test.

Exclusion criteria included a history of life-threatening arrhythmias, severe ventricular dysfunction (as measured by echocardiography), pulmonary HTN requiring vasodilators, HF requiring hospitalization in the past year, coronary artery stenosis or myocardial ischemia, coronary artery stenosis or myocardial ischemia, ventricular outflow tract stenosis with a systolic gradient greater than 50 mmHg, coronary artery stenosis or myocardial ischemia, and any medical or musculoskeletal conditions precluding participation in light-to-moderate aerobic exercise. Additional exclusions were acute or chronic respiratory illness, untreated causes of fatigue (e.g., hemoglobin <100 g/L, abnormal thyroid function), chronic renal failure with creatinine clearance <30 mL/min, and uncontrolled pulmonary disease.

Grouping:

The study included 35 post-Glenn (PG) surgery survivors, classified into two groups. The study group (n=15) participated in a CR program in addition to standard medical care. The control group (n=20) received the usual care without CR participation.

Ethical Considerations

Ethical approval was obtained from the Research Ethics Committee (REC) of Ain Shams University Faculty of Medicine, under approval number FWA 000017585/MS 698/2021. Informed consent was secured from parents or legal guardians for all participants.

STUDY PROTOCOL

History and Physical Examination

Each patient underwent a thorough history and physical examination, including details such as personal data, maternal age at birth, parental consanguinity, medical and surgical history, current symptoms, and medications. A comprehensive physical exam was conducted, including vital signs (blood pressure, heart rate), and anthropometric measurements such as BMI.

BMI classification was based on CDC growth charts for children and teenagers (aged 2-20) and WHO recommendations for adults (age >20). Cardiopulmonary examination included assessment of heart sounds, murmurs, basal crepitations, signs of cyanosis, and oxygen saturation using a pulse oximeter.

Echocardiography

All patients underwent an echocardiographic study both at baseline and after 12 weeks, using a GE Vivid S5N Ver. 10.3.0 b.114 machine with an RS3 probe. Key parameters assessed included left ventricular ejection fraction (LVEF) and end-diastolic diameter (EDD), evaluated by an experienced cardiologist.

Baseline Functional Capacity Assessment

Functional capacity was measured using 6MWT, a submaximal exercise test that evaluates the distance a patient can walk over six minutes. The test provides a comprehensive measure of cardiovascular, pulmonary, and musculoskeletal function. The 6MWT was conducted in a flat, 30-meter-long corridor, following American Thoracic Society guidelines 11. The heart rate, pulse oximetry, and blood pressure were measured at the beginning and end of the test, and the total distance walked was recorded.

Quality of Life Assessment

QoL was evaluated at baseline and after three months using the Minnesota Living with Heart Failure Questionnaire (MLHFQ), a self-assessment tool that focuses on the physical, psychological, and socioeconomic impacts of congenital heart disease. Nineteen items were used, as items 8 and 10 were deemed inappropriate for the study population 12.

Cardiac Rehabilitation Protocol

The CR program lasted 12 weeks, with each patient undergoing one-hour session twice a week.

Each session consisted of a warm-up period, treadmill exercise training, and a cooldown period. Patients received individualized counselling on cardiac risk factors and lifestyle modifications, including dietary and psychological consultations. The program encouraged patients to engage in 30-60 minutes of moderate-intensity physical activity on five or more days per week, supplemented with physical activity counselling.

Patient Risk Stratification

Patients with CHD were assessed based on hemodynamic factors rather than anatomical lesions.

Statistical Analysis

Data were evaluated with SPSS version 26 (IBM, Armonk, New York, United States). Quantitative factors were represented as mean ± standard deviation (SD), whereas qualitative variables were analyzed using the Wilcoxon Rank test and Chi-square test. A paired t-test was used to compare groups about quantitative factors. A p-value below 0.05 was deemed statistically significant.

RESULTS

Demographic data and history of study patients:

The demographic data of the 35 study patients show that 88.6% (31 patients) had no consanguinity up to grade 2, while 11.4% (4 patients) did. The mean maternal age at birth was 25.89 years, with a standard deviation of 4.11, and the range was 17 to 36 years. Regarding gender, 45.7% of the patients (16) were female, and 54.3% (19) were male. The patients had a mean ago of 12.85 years, with an SD of 3.35, and the age range was 8 to 21 years. The average weight of the patients was 43.3 kg, with an SD of 13.2, ranging from 25 to 74 kg. The mean height was 150.11 cm, with an SD of 14.032, and the range was 126 to 178 cm. The mean BMI was 18.68 kg/m², with an SD of 2.65, and the range was 14.7 to 24.4 kg/m². In terms of dominant ventricle morphology, 48.6% (17 patients) had an RV as the dominant ventricle, while 51.4% (18 patients) had an LV as the dominant ventricle.

No significant differences were observed between group 1 and group 2 regarding gender (46.7% vs. 45.0%, P = 0.922), age (12.97 ± 2.96 vs. 12.75 ± 3.68 years, P = 0.848), and dominant ventricular morphology (RV: 40.0% vs. 55.0%, P = 0.380). Table 1

Table 1:

Comparison between groups 1 and group 2 regarding demographic data and history of the studied patients.

		Group 1 No.=15	Group 2 No.=20	P-value
Gender	Female Male	7 (46.7%) 8(53.3%)	9 (45.0%) 11 (55.0%)	0.922
Age (years)	Mean ±SD	12.97 ± 2.96	12.75 ± 3.68	0.848
Dominant ventricular morphology (n)	RV LV	6 (40.0%) 9 (60.0%)	11 (55.0%) 9 (45.0%)	0.380

SD: Standard deviation, RV: Right ventricle, LV: Left ventricle, n (%): number (percentage).

At baseline, no significant variations were observed between Group 1 and Group 2 regarding echocardiographic parameters (EDD: P = 0.455, EF: P = 0.686), 6-minute walk distance (P = 0.300), heart rate pre-and post-6MWT (P = 0.136 and P = 0.062, respectively), or oxygen saturation pre- and post-6MWT (P = 0.367 and P = 0.586, respectively). Furthermore, no notable variations were found in QoL scores as assessed by MLHFQ in terms of physical (P = 0.061), emotional (P = 0.156), or total score (P = 0.181).

Table 2:

Comparison Between Group 1 and Group 2 on Admission Regarding Echocardiographic Parameters, 6-Minute Walk Test (6MWT), Heart Rate, Oxygen Saturation, and Quality of Life (MLHFQ)

Parameter	Group 1 (n=15)	Group 2 (n=20)	P-val-ue
EDD (cm)	5.27 ± 0.83	5.04 ± 0.95	0.455
EF (%)	58.67 ± 2.92	59.65 ± 8.96	0.686
6MWD (m)	378.67 ± 53.97	370.50 ± 37.41	0.300
HR pre (bpm)	92.27 ± 8.02	87.20 ± 10.78	0.136
HR post (bpm)	111.20 ± 11.90	104.50 ± 8.63	0.062
Saturation pre (%)	71.07 ± 8.08	71.73 ± 8.43	0.367
Saturation post (%)	61.80 ± 6.49	63.30 ± 8.93	0.586
MLHFQ Physical(n)	16 (9 – 18)	12 (9 – 13)	0.061
MLHFQ Emotional (n)	5 (4 – 9)	4.5 (2.5 – 5)	0.156
MLHFQ Total score QOL	19 (18 – 24)	17 (14.5 – 22)	0.181

EDD: End-diastolic diameter, cm: Centimeters, EF: Ejection fraction, 6MWT: 6-minute walk test, 6MWD: 6-minute walk distance, m: Meters, HR: Heart rate, bpm: Beats per minute, ML-HFQ: Minnesota Living with Heart Failure Questionnaire, QOL: Quality of life.

Cardiac Rehabilitation Program Performance Data for Group 1

In Group 1, patients completed an average of 23.33 ± 1.45 sessions, with a range of 20 to 24 sessions during CR program. The average speed achieved during the 20-minute exercise session was 3.23 ± 0.55 mph, with a range of 2.28 to 3.96 mph. The mean heart rate during the 20-minute session was 112.93 ± 12.29 bpm, ranging from 99 to 135 bpm. Oxygen saturation at 20 minutes averaged 60.1 ± 5.39%, with values ranging from 42.5% to 64%.

The 6MWD was significantly higher after 3 months (411.00 ± 61.01 m) compared to baseline (378.67 ± 53.97 m, P = 0.000). Pre-exercise heart rate significantly decreased after 3 months (84.93 ± 8.48 bpm vs. 92.27 ± 8.02 bpm, P = 0.013), while post-exercise heart rate was significantly higher (116.8 ± 11.36 bpm vs. 100 ± 11.39 bpm, P = 0.001). The physical score of the MLHFQ significantly improved (8 [7–12] vs. 16 [9–18], P = 0.004), as did the emotional score (2 [2– 4] vs. 5 [4 – 9], P = 0.019), and the total QoL score (16 [12–21] vs. 19 [18–24], P = 0.035). No notable changes were observed in echocardiographic parameters (EDD: P = 0.872, EF: P = 0.090), or in oxygen saturation before and after the exercise test (P = 0.367 and P = 0.103, respectively). Table 3

Table 3

Comparison of ECHO, 6MWT, Heart Rate, Oxygen Saturation, and Quality of Life (MLHFQ) in Group 1 on Admission and After 3 Months

Parameter	On Admission	After 3 Months	P-value
EDD (cm)	5.27 ± 0.83	5.28 ± 0.84	0.872
EF (%)	58.67 ± 2.92	60.13 ± 2.75	0.090
6MWD (m)	378.67 ± 53.97	411.00 ± 61.01	0.000
HR pre (bpm)	92.27 ± 8.02	84.93 ± 8.48	0.013
HR post (bpm)	100 ± 11.39	116.8 ± 11.36	0.001
Saturation pre (%)	71.07 ± 8.08	73.40 ± 8.24	0.367
Saturation post (%)	61.80 ± 6.49	66.70 ± 9.21	0.103
MLHFQ Physics	16 (9 – 18)	8 (7 – 12)	0.004
MLHFQ Emotional	5 (4 – 9)	2 (2 – 4)	0.019
MLHFQ Total QOL	19 (18 – 24)	16 (12 – 21)	0.035

EDD: End-diastolic diameter, cm: Centimeters, EF: Ejection fraction, 6MWD: 6-minute walk distance, m: Meters, HR: Heart rate, bpm: Beats per minute, MLHFQ: Minnesota Living with Heart Failure Questionnaire, QOL: Quality of life.

In Group 2, no notable changes were observed in echocardiographic parameters after 3 months, with EDD remaining at 5.09 ± 0.91 cm (P = 0.508) and EF increasing slightly but not significantly (P = 0.138). The 6MWD also showed no significant change after 3 months (P = 0.591). Similarly, there were no significant changes in heart rate before (P = 0.064) or after (P = 0.061) exercise, as well as in oxygen saturation pre- and post-exercise (P = 0.368 and P = 0.669, respectively). QoL scores, measured by the MLHFQ, also showed no significant improvements in the physical (P = 0.331), emotional (P = 0.298), or total QoL scores (P = 0.454) after 3 months of standard care. These findings indicate stability in both functional capacity and QoL without substantial improvements over the 3-month period in Group 2. Table 4

Table 4:

Comparison Between Group 2 on Admission and After 3 Months for Echo Parameters, 6MWD, Heart Rate, Oxygen Saturation, and Quality of Life (MLHFQ)

Parameter	On Admission	After 3 Months	P-value
EDD (cm)	5.04 ± 0.95	5.09 ± 0.91	0.508
EF (%)	59.65 ± 8.96	60.95 ± 8.41	0.138
6MWD (m)	370.50 ± 37.41	372.75 ± 39.92	0.591
HR pre (bpm)	87.20 ± 10.78	93.20 ± 12.11	0.064
HR post (bpm)	104.50 ± 8.63	99.10 ± 11.66	0.061
Saturation pre (%)	71.07 ± 8.08	73.25 ± 9.31	0.368
Saturation post (%)	63.30 ± 8.93	64.47 ± 8.48	0.669
MLHFQ Physics	12 (9 – 13)	12 (10.5 – 15.5)	0.331
MLHFQ Emotional	4.5 (2.5 – 5)	4.5 (3 – 6)	0.298
MLHFQ Total QOL	17 (14.5 – 22)	21 (16.5 – 22.5)	0.454

EDD: End-diastolic diameter, cm: Centimeters, EF: Ejection fraction, 6MWD: 6-minute walk distance, m: Meters, HR: Heart rate, bpm: Beats per minute, MLHFQ: Minnesota Living with Heart Failure Questionnaire, QOL: Quality of life.

After 3 months, Group 1 showed notable improvement in the 6-minute walk distance (411.00 ± 61.01 m) compared to Group 2 (372.75 ± 39.92 m, P = 0.032). Pre-exercise HR was significantly lower in Group 1 (84.93 ± 8.48 bpm) than in Group 2 (93.20 ± 12.11 bpm, P = 0.031), and post-exercise HR was also considerably lower in Group 1 (97.93 ± 11.15 bpm) compared to Group 2 (106.85 ± 11.14 bpm, P = 0.025). There were no notable changes between the groups in oxygen saturation pre- and post-exercise. Table 5

QoL, as measured by MLHFQ) showed significant improvements in Group 1, with lower physical (P = 0.018), emotional (P = 0.027), and total QoL scores (P = 0.017) compared to Group 2. Over the 3-month period, Group 1 demonstrated greater changes in 6MWD (P = 0.000), heart rate (pre- and post-exercise), and QoL scores, while no notable variations were observed in echocardiographic parameters (EDD and EF) for either group. Table 6

Table 5

Comparison Between Group 1 and Group 2 After 3 Months for Echo, 6MWT, Heart Rate, Oxygen Saturation, and Quality of Life (MLHFQ)

Parameter	Group 1 (n=15)	Group 2 (n=20)	P-value
EDD (cm)	5.28 ± 0.84	5.09 ± 0.91	0.533
EF (%)	60.13 ± 2.75	60.95 ± 8.41	0.721
6MWD (m)	411.00 ± 61.01	372.75 ± 39.92	0.032
HR pre (bpm)	84.93 ± 8.48	93.20 ± 12.11	0.031
HR post (bpm)	97.93 ± 11.15	106.85 ± 11.14	0.025
Saturation pre (%)	73.40 ± 8.24	73.25 ± 9.31	0.961
Saturation post (%)	66.70 ± 9.21	64.47 ± 8.48	0.463
MLHFQ Physics	8 (7 – 12)	12 (10.5 – 15.5)	0.018
MLHFQ Emotional	2 (2 – 4)	4.5 (3 – 6)	0.027
MLHFQ Total QOL	16 (12 – 21)	21 (16.5 – 22.5)	0.017

EDD: End-diastolic diameter, cm: Centimeters, EF: Ejection fraction, 6MWD: 6-minute walk distance, m: Meters, HR: Heart rate, bpm: Beats per minute, MLHFQ: Minnesota Living with Heart Failure Questionnaire, QOL: Quality of life.

Table 6

Changes Over 3 Months:

Parameter	Group 1	Group 2	P-value
EDD (cm)	0 (-0.1 – 0.2)	0 (-0.15 – 0.1)	0.852
EF (%)	0 (0 – 3)	0.5 (0 – 2)	0.905
6MWD (m)	30 (15 – 45)	0 (-15 – 15)	0.000
HR pre (bpm)	-8 (-15 – -2)	4 (-3 – 21)	0.004
HR post (bpm)	-14 (-26 – -2)	5 (-10 – 11)	0.006
MLHFQ Physics	-5 (-9 – -1)	2.5 (-3.5 – 5)	0.004
MLHFQ Emotional	-2 (-4 – -1)	0 (-0.5 – 1)	0.001
MLHFQ Total QOL	-4 (-7 – 1)	-0.5 (-2 – 4)	0.008

EDD: End-diastolic diameter, cm: Centimeters, EF: Ejection fraction, 6MWD: 6-minute walk distance, m: Meters, HR: Heart rate, bpm: Beats per minute, MLHFQ: Minnesota Living with Heart Failure Questionnaire, QOL: Quality of life.

DISCUSSION

This study represents, to our knowledge, the first in Egypt to assess the feasibility and effectiveness of CR in patients with a single ventricle (PG shunt).

While numerous studies have investigated the functional capacity of Fontan patients, there remains a notable gap in research focusing on patients who have undergone the Glenn procedure, as highlighted by Sen et al. 13. This points to two key epidemiological factors: first, the Glenn procedure is rarely considered the definitive palliation for univentricular heart repair in wealthier nations. Second, in these countries, the Fontan operation is generally performed at a young age, often by 5 or 6 years old, leaving many pre-Fontan patients too young to undergo comprehensive cardiopulmonary exercise testing.

In Egypt, the bidirectional Glenn (BDG) procedure is favored as the primary palliative intervention due to its lower complication rate compared to the Fontan surgery and the limited availability of heartlung transplantation, as noted by Tewfik et al. 14.

Echocardiography findings in this study showed no significant changes in echocardiographic parameters at baseline and follow-up in both groups, nor was there a correlation between cardiac function and exercise capacity. This could be attributed to the use of a submaximal test, which does not place significant stress on cardiac function (such as ventricular ejection fraction) or, consequently, on cardiac output, as seen in other studies 15. However, echocardiographic changes can have significant hemodynamic consequences, increasing long-term mortality risk and reducing exercise capacity 16, 17, which may partially explain the decline in exercise tolerance observed in this study.

The six-minute walk test was used to assess the functional capacity of our 35 patients, with an average distance of 378.67 ± 53.97 meters. In a similar study, Sen et al. 13 evaluated 44 post-BDG patients, reporting an average distance of 374 ± 83 meters. Our study showed a significant improvement in walking distance after three months (mean 411.00 ± 61.01 meters), aligning with the findings of Moala et al. 18.

A statistically significant difference was observed between the baseline and post-exercise heart rates (HRs) (-7.34 vs. -13.27, P = 0.013 vs. P = 0.011), though oxygen saturation only showed a slight decrease.

Most follow-up studies of adults with congenital heart disease (ACHD) focus primarily on severe morbidity and mortality. However, ‘health’ extends beyond physical wellness to include mental, social, and psychological aspects, making health-related quality of life (HRQoL) a multifaceted concept. Multiple studies have reported that the quality of life in ACHD patients is generally lower compared to the general healthy adult population 17, 19. In contrast, research by Moons et al. suggested that individuals with congenital heart disease rated their quality of life as higher than that of their healthy counterparts 20.

Various validated tools are used to assess QoL. In our study, the MLHFQ was employed, and it revealed a significant improvement following the CR program. This aligns with findings by Gierat-Haponiuk et al.21, who reported positive effects of CR programs on physical activity and QoL in long-term follow-ups after surgical correction of congenital heart disease. Conversely, Winter et al. 22, in their randomized clinical trial using the SF-36 and CHD-TAAQOL, found no improvement in QoL over a 10-week period of exercise training.

The primary limitations of this study include the small sample size, which may reduce the statistical power and limit the external validity of the findings. Additionally, the relatively short follow-up period restricts the evaluation of long-term effects of CR in this population. The absence of blinding may have introduced observer bias in the assessment of functional capacity and QoL. Furthermore, the single-center design may limit the generalizability of the results to other patient populations. Finally, while the 6-minute walk test is a widely accepted measure of functional capacity, it may not comprehensively reflect the full spectrum of cardiovascular and exercise performance.

CONCLUSION

In conclusion, the results of this prospective, two-arm, parallel, randomized, controlled clinical trial demonstrate that a completed CR program improves QoL and the 6MWD in patients with PG shunt and restricted physical activity.