Introduction
Adults with congenital heart disease (CHD) have an increased risk of early atherosclerosis-related events, as myocardial infarction and stroke. Reference Lui, Rogers and Ding1 However, these patients were not fully considered a high-risk group for atherosclerosis on guidelines for cardiovascular disease prevention in children and adults with CHD. Reference Urbina, Williams and Alpert2,Reference Piepoli, Hoes and Agewall3 Although, previous studies described that obesity, dyslipidemia, diabetes mellitus, and physical inactivity affect children and adolescents with CHD. Reference Barbiero, D’Azevedo Sica and Schuh4,Reference Massin, Hovels-Gurich and Seghaye5 Besides, some types of CHD or surgical repair were associated with coronary disease. Reference Pasquali, Marino and Powell6
In at least 10% of healthy children and adolescents is observed the presence of subclinical atherosclerosis, Reference Weberruss, Pirzer and Bohm7 as supported by the structural changes in the arterial walls determined by carotid intima-media thickness. Reference Gooty, Sinaiko and Ryder8 Longitudinal studies evidence that early structural changes in arterial walls in childhood can predict the development of cardiovascular disease in adulthood. Reference Berenson, Wattigney and Tracy9,Reference Magnussen, Smith and Juonala10 The elevated carotid intima-media thickness was associated with a higher incidence of myocardial infarction and stroke. Reference Gooty, Sinaiko and Ryder8 However, no studies have demonstrated the socio-demographic, clinical characteristics, and cardiovascular risk factors associated with carotid intima-media thickness in children and adolescents with CHD. Thus, identifying the factors that contribute to the development of atherosclerosis may be an opportunity to reduce atherosclerosis progression and increase the life expectancy in this population. The aims of this study were to evaluate carotid intima-media thickness and, to investigate associated factors with subclinical atherosclerosis in children and adolescents with CHD.
Materials and methods
Design and population study
A cross-sectional study was conducted with children and adolescents with CHD, who underwent invasive treatment (cardiac surgical or interventional catheterisation for CHD), attended in the cardiology outpatient care of two referral hospitals, in Florianopolis, Santa Catarina, Brazil, from January to July 2017. The selection criteria were: (1) had CHD ever corrected, totally or partially, (2) aged between 5 and 18 years, (3) attended in the cardiology outpatient care of this study. The exclusion criteria were: (1) clinical conditions that prevented the anthropometric assessment, (2) genetic syndromes, (3) chronic disease (diabetes mellitus, hypothyroidism, kidney disease, chronic inflammatory disease), and (4) acute disease 15 days prior to the assessment. The parents or legal guardians of patients were contacted through telephone, and those who agreed to participate were scheduled for data collection. The sample size was calculated according to the following criteria: (1) prevalence of subclinical atherosclerosis in childhood and adolescence with CHD unknown; (2) CHD patients attended in cardiology outpatient care of this study (n = 430) (2) type 1 error (α) of 0.05 (3) the type 2 error (ß) of 0.20, and (4) 95% confidence interval. For this study, the calculated sample size was 206 patients.
Subclinical atherosclerosis
The subclinical atherosclerosis was determined by carotid intima-media thickness. Ultrasound of carotid arteries was performed using the Toshiba Viamo® ultrasound, with previously calibrated and 7.5 MHz linear transducers. The procedure was conducted with the patient in a supine position, with head slightly elevated and toward the opposite sides of the medical examiner. Six images were captured in the arterial diastole, and the three with the best quality were selected. All tests were performed by a paediatric cardiologist with suitable medical qualifications and training, followed the recommendations. Reference Stein, Korcarz and Hurst11 The carotid intima-media thickness was measured using the software (M’ath®, Metris SRL, Argenteuil, France), with a digital readout of 100 points of the right common carotid, the midpoint of common carotid bifurcation of 1 cm and calculated automatically measures the mean of three best images. Reference Jourdan, Wuhl and Litwin12 The carotid intima-media thickness was expressed in millimeter. For this study, atherosclerosis subclinical was considered as carotid intima-media thickness ≥97th percentile, according to the carotid intima-media thickness reference values for age and sex. Reference Weberruss, Pirzer and Bohm7 It was categorised into two groups: (1) <97th percentile and (2) ≥97th percentile. Moreover, carotid plaque was assessed as a carotid intima-media thickness value ≥1.5 mm or a focal intimal medial thickening of ≥50% of the surrounding area.
Socio-demographic characteristics
Age (in years); sex (male versus female); skin colour described by the patients (white versus non-white); income per capita, calculated as the Brazilian minimum wage from February 2017 [$295.00] divided by the number of household members (<1 wage versus ≥1 wage); mother’s education (<10 years versus ≥10 years).
Clinical characteristics
CHD were categorised according to the International Statistical Classification of Diseases and Related Health Problems-10 codes, as follows: Conotruncal defects (e.g., truncus arteriosus, transposition of the great arteries and tetralogy of Fallot); Nonconotruncal defects: (e.g., total, partial, intermediate atrioventricular septal defect, single ventricle, tricuspid atresia, pulmonary atresia, hypoplastic left heart syndrome, and Ebstein anomaly); Coarctation of aorta; Ventricular septal defect; Atrial septal defect; Others CHD, Reference Liu, Joseph and Luo13 This classification system was based in cardiac phenotype, cardiac complexity, and extracardiac anomalies. Reference Liu, Joseph and Luo13–Reference Liu, Joseph and Lisonkova15 Type of CHD is defined according to the diagnosis of congenital heart disease and later classified as cyanotic versus acyanotic. Reference Burch16 The cardiac procedure (cardiac catheterisation versus cardiac surgery), number of cardiac procedures (≤ 1 time versus ≥ 2 times), post-operative time in years, medicine use, as such angiotensin-converting enzyme inhibitors, beta-blockers, diuretics, antiplatelet and anticoagulants (yes versus no) were investigated by parent’s interviews. Hospitalisations for infection was defined through the question for guardians “Has your child ever been hospitalized for infection (e.g. pneumonia, infection due to a cardiac procedure)?” and categorized as yes or no. Birth weight (small for gestational age versus appropriate for gestational age, and large for gestational age) Reference Lubchenco, Hansman and Dressler17 and family history of early cardiovascular disease (yes versus no) were also collected at these interviews. Still, the clinical characteristics were confirmed at medical records of each participant.
Cardiovascular risk factors
Physical activity was evaluated through the Physical Activity Questionnaire for Children, Reference Crocker, Bailey and Faulkner18 expressed in score, and classified as inactive (score from 1 to 3) or active (score from 4 to 5). Screen time was evaluated by a direct question and was considered the time spent with television computer, tablets, phones, and/or electronic games per day (≥2 hours per day – as abnormal – versus <2 hours per day), Reference Tremblay, LeBlanc and Kho19 also passive smoke was checked (yes versus no). Blood pressure was measured using a mercury sphygmomanometer according to recommendations. Systolic and diastolic blood pressure was expressed in percentile for sex, age, and height. 20 Waist circumference was measured at the superior border of the iliac crest and classified according to the cut-off points indexed by age and sex (no abdominal adiposity [<75th percentile] versus abdominal adiposity [≥ 75th percentile]). Reference Fernández, Redden and Pietrobelli21 Dietary intake was assessed using three 24-hour recall with the multiple-pass method, Reference Conway, Ingwersen and Vinyard22 two of them on weekdays and one of them on weekend. Energy and nutrient intakes were analysed using the Nutrition Data System software for Research® version 2017. Dietary intake variables were standardised (standard score) to facilitate the interpretation of the logistic regression results. Blood samples were collected in peripheral venous puncture in the morning after 12 hours of fasting. Lipid parameters: total cholesterol, high-density lipoprotein-cholesterol, low-density lipoprotein-cholesterol, triglycerides, and glycaemia were measured in the serum. The total cholesterol and triglycerides concentrations were determined with the enzymatic method (Dimension©; Siemens). High-density lipoprotein-cholesterol levels were determined using a direct in vitro method. Low-density lipoprotein-cholesterol levels were calculated with the Friedewald formula (there was no triglycerides above 400 mg/dL). The non-high-density lipoprotein-cholesterol was calculated by the difference between triglycerides and high-density lipoprotein-cholesterol values. The reference values used were extracted from the Guidelines for Cardiovascular Health and Risk Reduction in Children and Adolescents for lipids. 23 Fasting glycaemia was determined by colorimetric enzymatic. Glycaemia values were classified according to the American Diabetes Association. 24 C-reactive protein was determined with the immunonephelometry method, and classified as high cardiovascular risk if >3 mg/L. 23
Statistical analysis
Data analysis was performed using SPSS version 23 (SPSS, Inc., Chicago, IL, USA). Descriptive data were described in relative and absolute frequency, and 95% confidence interval for categorical variables and in means, standard deviation or median and interquartile range for continuous variables.
The mean of carotid intima-media thickness was compared with CHD according to the International Statistical Classification of Diseases and Related Health Problems-10 codes using ANOVA test. Post hoc test Bonferroni was also performed. Bivariate logistic regression analysis was used to assess the association of carotid intima-media thickness (outcome variable) to socio-demographic and clinical characteristics and, cardiovascular risk factors (exposure variable), expressed in odds ratios and respective 95% confidence interval. In multiple logistic regression model, forward selection was applied to investigate the factors associated with carotid intima-media thickness. The multiple logistic regression model was adjusted for the following confounding factors: age, sex, income, energy and fiber intake, postoperative time, medications, C-reactive protein, non-high-density lipoprotein-cholesterol, screen time, and waist circumference; these variables were considered confounding factors by statistical significance (p < 0.20) and previous study on subclinical atherosclerosis. Also, the variables that showed multicollinearity were excluded from the model (r = 0.5). The goodness of fit of our model was assessed using Homer and Lemeshow test. The model was determined to be a good model if the Homer and Lemeshow test was higher 0.8. All p-values <0.05 were considered statistically significant.
Results
A total of 227 patients, aged between 5 and 18 years were included in this study. One patient has exclusion criteria (diagnosis of nephrotic syndrome) and five patients were excluded due to insufficient image quality in the carotid intima-media thickness (Supplementary Figure S1). The median age was 10.03 (interquartile range 7.09; 13.05) years, 65.6% had acyanotic CHD and the mean postoperative time was 6.73 (standard deviation ±3.84) years. Socio-demographic and clinical characteristics are shown in Table 1. Physical inactivity was the most prevalent cardiovascular risk factor, identified in 98.2% of children and adolescents with CHD. Other cardiovascular risk factors were also prevalent, as screen time ≥2 hours per day (52.9%), abdominal obesity (24.7%), passive smoke (23.8%), borderline glucose (13.2%), high C-reactive protein (12.8), low high-density lipoprotein-cholesterol (9.7%), high non-high-density lipoprotein-cholesterol (9.3), high low-density lipoprotein-cholesterol (7.0%), and high triglycerides (6.6%).
Table 1. Socio-demographic and clinical characteristics
AGA = appropriate for gestational age; CI = confidence interval; LGA = large for gestational age; n = number; SGA = small for gestational age; % = percentage.
a 2 patients did not know inform; bthe Brazilian minimum wage in February 2017 – $295.00; c23 patients did not know inform birth weight; d2 patients did not know inform; e3 patients did know inform
In all children and adolescents with CHD, the mean of carotid intima-media thickness was 0.518 (standard deviation ±0.07) mm and 46.7% had atherosclerosis subclinical. No patient had any carotid plaque. The CHD diagnosis with highest values of carotid intima-media thickness was the coarctation of the aorta (0.558 [standard deviation 0.06] mm) and 76.9% had subclinical atherosclerosis. The mean of carotid intima-media thickness and subclinical atherosclerosis according to the CHD diagnoses by International Statistical Classification of Diseases and Related Health Problems-10 codes are described in Table 2.
Table 2. Mean of carotid intima-media thickness and subclinical atherosclerosis
n = number; SD = standard deviation; % = percentage.
* categorised according to the International Statistical Classification of Diseases and Related Health Problems-10 codes, as follows: Conotruncal defects (e.g., truncus arteriosus, transposition of the great arteries and tetralogy of Fallot); Nonconotruncal defects: (e.g., total, partial, intermediate atrioventricular septal defect, single ventricle, tricuspid atresia, pulmonary atresia, hypoplastic left heart syndrome and Ebstein anomaly); Coarctation of the aorta; Ventricular septal defect; Atrial septal defect and Others congenital heart diseases.Reference Liu, Joseph and Luo13
p-value obtained by the ANOVA
aSignificant difference between Conotruncal defects and Coarctation of the aorta with p-value <0.05 (Bonferroni); bSignificant difference between Coarctation of the aorta and Atrial septal defect with p-value <0.05 (Bonferroni)
Bivariate logistic regression showed that cardiac procedure (cardiac surgery) was associated with increased odds of subclinical atherosclerosis (Table 3) and total fiber intake (per each 1 increment the standard score) was associated with decreased odds of subclinical atherosclerosis (Table 4). The other socio-demographics and, clinical characteristics and cardiovascular risk factors were not associated with subclinical atherosclerosis (Tables 3 and 4).
Table 3. Association between socio-demographics and clinical characteristics with subclinical atherosclerosis
AGA = appropriate for gestational age; CI = confidence interval; LGA = large for gestational age; OR = Odds ratio; REF = reference; SGA = small for gestational age.
a the Brazilian minimum wage in February 2017 – $295.00;
* carotid intima-media thickness: ≥97th percentile;
p-values calculated using bivariate logistic regression. p-values that are statistically significant (p-value < 0.05)
Table 4. Association between cardiovascular risk factors with subclinical atherosclerosis
CI = confidence interval; CRP = C-reactive protein; DBP = diastolic blood pressure; HDL-C = high-density lipoprotein-cholesterol; LDL-C = low-density lipoprotein-cholesterol; MUFA = Monounsaturated fatty-acids; OR = Odds ratio; PUFA = Polyunsaturated fatty-acids; REF = reference; SBP = systolic blood pressure; SD = standard deviation; SFA = Saturated fatty-acids. kcal/d, kilocalorie per day; %E/d, percentage of energy per day; mg/d, milligram per day; g/d, gram per day; g/kg/d = gram per kilogram per day.
* carotid intima-media thickness ≥97th percentile;
Reference values: CRP: low and moderate (<3 mg/L) and high (≥3 mg/L); Total Cholesterol: low and borderline (<200mg/dL) and high (≥200 mg/dL); LDL-c: low and borderline (<130 mg/dL) and high (≥130 mg/dL); HDL-c: high: ≥40 mg/dL and low: and borderline <40 mg/dL; Non-HDL-c: low and borderline <145 mg/dL and high ≥145 mg/dL; Triglycerides: low and borderline (<100/130 mg/dL) and high (≥100/130 mg/dL), value according age: 0–9 years/10–19 years, respectively); Glycaemia: low and borderline (<100 mg/dL) and high (≥100 mg/dL).
p-values calculated using bivariate logistic regression. p-values that are statistically significant (p-value < 0.05)
In multivariable model, cyanotic CHD (odds ratio: 0.40; 95% confidence interval: 0.20; 0.78) was associated with decreased odds of subclinical atherosclerosis, while the cardiac surgery (odds ratio: 3.17; 95% confidence interval 1.35; 7.48) and hospitalisations for infections (odds ratio: 1.92; 95% confidence interval: 1.04; 3.54) were associated with an increased odds of subclinical atherosclerosis (Table 5).
Table 5. Logistic regression factors associated with elevated carotid intima-media thickness
CI = confidence intervals; OR = Odds Ratio; REF = reference
* carotid intima-media thickness: ≥97th percentile;
a Adjusted for age (years), sex (male versus female), income per capita (≤1 wage versus >1 wage), energy (1 standard deviation), fiber (1 standard deviation), postoperative time (years), medications, C-reactive protein (mg/dL), non-high-density lipoprotein-cholesterol (mg/dL), screen time (<2 hours per day versus ≥2 hours per day), waist circumference (no abdominal adiposity [<75th percentile] versus abdominal adiposity [≥75th percentile]).
p-values calculated using logistic regression. p-values that are statistically significant (p-value < 0.05).
Homer and Lemeshow from multivariable model = 0.863.
Discussion
Although several studies have demonstrated a high prevalence of risk factors for atherosclerosis in children and adolescents with CHD, Reference Massin, Hovels-Gurich and Seghaye5,Reference Schwartz, Olsen and Woo25 to our knowledge, the present study was the first to investigate associated factors with subclinical atherosclerosis in children and adolescents with CHD. The main findings of this study were that clinical characteristics, as cyanotic CHD, be submitted to cardiac surgery, and be hospitalized to treat infections were associated with subclinical atherosclerosis. These findings suggest that CHD plays an important role in atherogenesis.
The mean of carotid intima-media thickness was 0.518 (standard deviation 0.07) mm in the present study, higher than mean of carotid intima-media thickness in healthy children. Reference Weberruss, Pirzer and Bohm7,Reference Dalla Pozza, Pirzer and Beyerlein26–Reference Doyon, Kracht and Bayazit28 Moreover, another cross-sectional study in children and adolescents with congenital heart disease found greater carotid intima-media thickness in heart patients compared to healthy children (carotid intima-media thickness = 0.464 ± 0.039 mm versus = 0.449 ± 0.045 mm; p = 0.003). Reference Reiner, Oberhoffer and Hacker29 Similarly, children and adolescents with coarctation of the aorta also had higher carotid intima-media thickness compared to the control group (carotid intima-media thickness = 0.48 ± 0.08 versus 0.38 ± 0.05 mm; p<0.001). Reference Meyer, Joharchi and Kundt30 These findings suggest risk for atherosclerotic heart disease in children and adolescents with congenital heart disease, when compared with the general population.
Cardiovascular risk factors are known to be involved in atherosclerosis pathogenesis, as obesity, hypertension, dyslipidemia, Reference van Rooy and Pretorius31 unhealthy diet (i.e. high fat and sugar foods and lower fibers), Reference Martins e Silva and Saldanha32 and sedentary lifestyle, as well as inflammatory diseases. Reference Germano-Soares, Andrade-Lima and Menêses33 Thus, the presence of cardiovascular risk factors can contribute to the process of accelerated atherosclerosis in CHD patients. Reference Barbiero, D’Azevedo Sica and Schuh4 Although the cardiovascular risk factors were not associated with atherosclerosis in this present study, these factors take part of the atherogenic process, and it need to be taken into account on the atherosclerotic prevention in these patients. It is important to note that cardiovascular risk factors such as abdominal obesity, physical inactivity, high C-reactive protein are already present in our patients, which may not have an impact on atherosclerosis now, but it can lead to harmful effects on cardiovascular health in adulthood.
In the present study, the hospitalisations for infections were associated with subclinical atherosclerosis. Infectious diseases can contribute to the early stages of atherosclerosis, inflammation, and endothelial dysfunction. Reference Charakida, Donald and Terese34 The occurrence of infectious disease can be the initial stimulus on atherogenesis in the healthy population and with any comorbidity. Reference Charakida, Donald and Terese34,Reference Libby35
One relevant finding of this study was that cyanotic CHD patients were associated with a lower risk of atherosclerosis subclinical. In agreement with our result, previous studies described that cyanotic CHD patients were free of coronary plaques or stenosis evaluated by coronary angiography. Reference Fyfe, Perloff and Niwa36,Reference Perloff37 Cyanotic CHD patients may have lower levels of total cholesterol and low-density lipoprotein-cholesterol levels compared to the acyanotic CHD. Reference Perloff37 Moreover, Çiftel and collaborators suggest that chronic hypoxic endothelium prevents the formation of atherosclerosis in children with CHD with pulmonary hypertension. Reference Ciftel, Simsek and Turan38 In adults, cyanotic CHD is associated with lower values of carotid intima-media thickness in comparison to acyanotic CHD, as well as, lower concentrations of total cholesterol, hyperbilirubinemia, and systolic and diastolic blood pressure. Reference Duffels, Mulder and Trip39 The hypothesis for this atherogenesis protection in cyanotic CHD is the hypoxemia that could prevent intramural fat accumulation and plaque formation. Reference Tarp, Jensen, Engstrom, Holstein-Rathlou and Sondergaard40
Furthermore, be submitted to cardiac surgery were associated with increased odds of subclinical atherosclerosis, compared to be submitted to cardiac catheterisation. This result can be attributed to the fact that patients with CHD corrected by cardiac surgery often have more serious type of CHD and could be exposed to higher levels of chronic inflammation than patients who underwent cardiac catheterisation. Among patients with coarctation of aorta, at the surgery, intrinsic vascular reactivity abnormalities occurred, and consequently can lead to endothelial dysfunction. Increased proinflammatory cytokines could bring long-term consequences, resulting in arterial dysfunction and structural atherosclerosis. Reference Martins e Silva and Saldanha32
Besides, a previous study has shown be submitted to coarctation of the aorta correction is significantly related to death by ischemic heart disease (25–37%) in adulthood. Reference Toro-Salazar, Steinberger and Thomas41 Therefore, this result suggests that haemodynamic and vascular abnormalities lead to changes in the structure of the artery wall, which can lead to acceleration of the progression of atherosclerosis. In the present study, 39 children and adolescents have coarctation of the aorta, and 76% of these patients were classified with carotid intima-media thickness above 97th percentile, while 47% of the other children and adolescents of this sample were classified as with subclinical atherosclerosis. This finding agreed with another study with corrected coarctation of the aorta adults that have higher values of carotid intima-media thickness when compared to the control group, and suggest that the endothelial dysfunction remains even after the repair and predisposes to the acceleration of atherosclerotic. Reference Luijendijk, Lu and Heynneman42
The occurrence of cardiac malformation can lead to the same endothelial dysfunction of other diseases, such diabetes mellitus, chronic renal disease, nephrotic syndrome, heart or kidney post-transplantion, Kawasaki disease, chronic inflammatory diseases – as human immunodeficiency virus infection – which are considered high risk for atherosclerosis since childhood. Reference Bohr, Fuhlbrigge and Pedersen43,Reference Rostampour, Fekri and Hashemi-Dehkordi44 Thus, multiple comorbidities, such as infections, surgeries, medications, treatment failure, or other inflammatory processes, may increase the high inherent risk. Besides, these multiple comorbidities can cause a series of chronic and repeated insults to the endothelium that has just suffered a process of remodelling at arterial wall, which culminates with the clinical manifestation of atherosclerosis in adulthood. Reference Urbina, Williams and Alpert2,Reference Rostampour, Fekri and Hashemi-Dehkordi44,Reference Burgner, Cooper and Moore45
The study has some limitations: a) the cross-sectional design, so it is not possible to establish a cause-and-effect relationship; b) the inherent limitation of the method to assess dietary intake; c) physical activity assessment may be limited due to recall; d) patients showed different postoperative time; e) different exposure time to cardiovascular risk factors; f) the absence of a representative control group that was impossible to form, because these children came for a vast territory served by regional reference centres, where the study was developed. Because that, we used cut-off points established at a recognised previous study, Reference Weberruss, Pirzer and Bohm7 and g) the use of extracorporeal membrane oxygenation influences the inflammatory process; however, it was not implemented in patients who have undergone cardiac surgery in this study. The strengths of our study include: a) assessment of carotid intima-media thickness in children and adolescents with CHD in a large sample b) use of multiple pass in dietary intake, and c) the method of carotid intima-media thickness assessment by software M’ath.
In conclusion, the main determinant of subclinical atherosclerosis was CHD itself (cardiac procedure, type of CHD, and be hospitalised to treat infections). Our findings may help the decision-making of paediatric cardiology teams, to plan the treatment, since the diagnosis until the follow-up, considered also the possibility of this late complication. Children and adolescents with CHD should be considered as a high-risk group for the development of atherosclerosis. Paediatric cardiologists should take in mind the important of intensive infections and cardiovascular risk factors control, to prevent the acceleration of the atherosclerotic process. Future prospective studies are necessary to explore the atherosclerosis process in CHD patients.
Acknowledgements
We are deeply grateful to the children, adolescents, and their families; officials from laboratories and clinics involved; and those who indirectly assisted in any way to the data collection and analysis.
Financial support
None.
Conflict of interest
None of the authors has any conflict of interest to disclosure.
Ethical standards
This study was approved by the Ethics Committee of the Federal University of Santa Catarina under the number 1.877.783 and complied with the 1964 Helsinki Declaration and its later amendments.
