A common angiotensin-converting enzyme polymorphism and preoperative angiotensin-converting enzyme inhibition modify risk of tachyarrhythmias after congenital heart surgery

Precision Medicine in Pediatric Cardiology

Precision medicine is a developing strategy for individualized treatment of a wide range of diseases. Congenital heart disease is the most common of all congenital defects and carries a high degree of variability in outcomes because of unidentified causes. Advances have identified individual genetic and environmental factors that have helped understand variations in morbidity and mortality in pediatric cardiology. A focus on genomics and pharmacogenetics has also been key to risk prediction and improvement in drug safety and efficacy in the pediatric population. With the rapidly evolving understanding of these individual factors, there also come challenges in implementation of personalized medicine into our health care model. This review outlines the key features of precision medicine in pediatric cardiology and highlights the clinical effects of these findings in patients with congenital heart disease. [Pediatr Ann. 2022;51(10):e390-e395.].

Angiotensin-converting enzyme insertion/deletion (ACE I/D) gene polymorphism in Egyptian children with congenital heart disease

BACKGROUND

Congenital heart diseases (CHDs) are the leading cause of infant deaths worldwide. The relationship between angiotensin-converting enzyme (ACE) gene polymorphism and CHDs is not clear. The aim of this work is to assess the presence of an association between ACE I/D polymorphism and CHD in Egyptian population.

SUBJECTS AND METHODS

Seventy CHD cases and 70 controls were incorporated in this study. DNA was isolated from their peripheral blood, and then ACE I/D gene polymorphism was tested by polymerase chain reaction (PCR).

RESULTS

There was no significant difference among the frequencies of the DD, II, and DI genotypes in patients and controls (26 [37.1%], 37 [53.3%], and 4 [5.7%], 5 [6.7%]), 40 (57.2%), 28 (40%), respectively (p value = 1 and OR [95% CI] = 1.1). There was no significant difference between D allele (DD + DI) and II genotype distribution among patients and controls (p value = 1 and OR [95% CI] = 1.2 [0.3-2.9]). Moreover, there was no difference between I allele (II + DI) and DD frequency (p value = 0.2 and OR [95% CI] = 0.6 [0.3-1.2]).

CONCLUSIONS

ACE I/D gene polymorphism might not be a risk factor of CHD in Egyptian children. Additional widespread studies are needed to affirm these data.

Metabolic Response to Stress by the Immature Right Ventricle Exposed to Chronic Pressure Overload

Background

The right ventricle exposed to chronic pressure overload exhibits hypertrophy and decompensates when exposed to stress. We hypothesize that impaired ability to increase myocardial oxidative flux through pyruvate dehydrogenase leads to hypertrophied right ventricular (RV) dysfunction when exposed to hemodynamic stress, and pyruvate dehydrogenase stimulation can improve RV function.

Methods and Results

Infant male Yorkshire piglets (13.5±0.6 kg weight, n=19) were used to assess substrate fractional contribution to the citric acid cycle after sustained pulmonary artery banding (PAB). Carbon 13–labeled glucose, lactate, and leucine, oxidative substrate tracers for the citric acid cycle, were infused into the right coronary artery on 7 to 10 days after PAB. RV systolic pressure, RV free wall thickness, and individual cardiomyocyte cell size after PAB were significantly elevated compared with the sham group. Both fractional glucose and lactate oxidations in the PAB group were >2‐fold higher than in the sham group. Pigs with overdrive atrial pacing (≈80% increase in heart rate) stress after PAB showed only a 22% increase in rate‐pressure product from baseline before atrial pacing and limited carbohydrate oxidation rate in the right ventricle. Intracoronary infusion of dichloroacetate, a pyruvate dehydrogenase agonist, produced higher rate‐pressure product (59% increase) in response to increased workload by atrial pacing in association with a marked increase in lactate oxidation.

Conclusions

The immature hypertrophied right ventricle shows limited ability to increase carbohydrate oxidation in response to tachycardia stress leading to energy supply/utilization imbalance and decreased systolic function. Enhanced pyruvate dehydrogenase activation by dichloroacetate increases energy supply and preserves hypertrophied RV contractile function during hemodynamic stress.

Incidence and effect of early postoperative ventricular arrhythmias after congenital heart surgery

BACKGROUND

Postoperative arrhythmias after pediatric congenital heart disease (CHD) surgery are a known cause of morbidity and are associated with mortality. A comprehensive evaluation of early postoperative ventricular arrhythmias (VAs) after CHD surgery has not been reported.

OBJECTIVES

We sought to determine the incidence of in-hospital VAs after CHD surgery and assess the clinical relevance of this arrhythmia during the postoperative hospital course.

METHODS

Patients undergoing CHD surgery at our center from September 2007 through December 2016 were prospectively enrolled. Univariate and multivariate analysis was used to assess the association between postoperative VAs and in-hospital mortality, adjusting for postoperative extracorporeal membrane oxygenation and stage 1 single ventricle palliation operations.

RESULTS

A total of 2503 postoperative courses in 1835 patients were included. In all, 464 (18.5%) had VAs, of whom 135 (29.1%) received treatment. Monomorphic ventricular tachycardia was the most frequently treated ventricular arrhythmia (TVA; n=91 [62.3%]). TVAs were associated with increased postoperative extracorporeal membrane oxygenation (13.3% vs 5.5%; P < .001) and in-hospital mortality (14.9% vs 4.0%; P < .001). In multivariate analysis, TVA was an independent risk factor for in-hospital mortality (adjusted odds ratio 2.44; 95% confidence interval 1.21-4.92).

CONCLUSION

Early postoperative VAs after CHD surgery are more common than previously reported. Postoperative VAs are associated with increased in-hospital mortality, and the subgroup of TVAs is an independent risk factor for in-hospital mortality.

Analysis of clinical and candidate genetic risk factors for postoperative atrial tachycardia after congenital heart surgery in infants

BACKGROUND

Atrial tachycardia (AT) after infant congenital heart disease (CHD) surgery is associated with increased mortality. Polymorphisms in PITX2 (rs2200733) and IL6 (rs1800795) are associated with postoperative atrial fibrillation in adults but have not been studied in CHD. The objective was to test the hypothesis that clinical factors and variants in PITX2 and IL6 are associated with postoperative AT in infants with CHD.

METHODS

Infants (<1 year of age) undergoing CHD surgery between September 2007 and May 2016 were included. Subjects had daily assessment of telemetry and were genotyped for the 2 variants. Univariate and multivariate analyses were performed to test for factors independently associated with AT.

RESULTS

Of 1,067 enrolled infants, 164 had postoperative AT (15.4%); 95 required treatment (8.9%). AT was associated with risk for extracorporeal membrane oxygenation, operative mortality, and longer duration of ventilation, as well as intensive care unit and hospital stays. PITX2 and IL6 genotypes were not associated with AT or AT requiring treatment. In multivariate analysis, use of 2 or more inotropes, age ≤ 28 days; Risk Adjusted classification for Congenital Heart Surgery, Version 1, score ≥ 3; and bypass time were all independently associated with AT. Factors independently associated with treated AT include use of 2 or more inotropes; age ≤ 28 days; and Risk Adjusted classification for Congenital Heart Surgery, Version 1, score ≥ 3.

CONCLUSION

AT occurs in 15% of infants after CHD surgery and is associated with increased morbidity and mortality. Risk factors include use of 2 or more inotropes, neonatal age, and higher surgical complexity score. We observed no association between common genetic variants in PITX2 and IL6 and AT in infants after CHD surgery.

Tell me once, tell me soon: parents' preferences for clinical genetics services for congenital heart disease

PURPOSE

As the molecular basis of congenital heart disease (CHD) comes into sharper focus, cardiac genetics services are likely to play an increasingly important role. This study aimed to identify parents' preferences for, and willingness to participate in, clinical genetics services for CHD.

METHODS

A discrete choice experiment was developed to assess parents' preferences for pediatric cardiogenetics services based on four attributes: appointment format, health professionals involved, waiting time, and information format. Data were analyzed using a mixed logit model.

RESULTS

One hundred parents with a living child diagnosed with CHD requiring surgical intervention between 2000 and 2009 completed the discrete choice experiment. Parents expressed a clear preference for cardiac genetics services featuring (i) a single appointment, (ii) the presence of a clinical geneticist and a genetic counselor, (iii) both verbal (oral) and Web-based information about CHD and genetics, and (iv) availability of an appointment within 2 weeks. If offered such conditions, 93% of respondents indicated that they would attend. The choice of service was most strongly influenced by the presence of both a clinical geneticist and a genetic counselor.

CONCLUSION

Parents of children with CHD favor a single, timely genetics appointment with both a geneticist and a genetic counselor present. If appointments offered match these preferences, uptake is likely to be high.

Advances in the Genetics of Congenital Heart Disease: A Clinician's Guide

Our understanding of the genetics of congenital heart disease (CHD) is rapidly expanding; however, many questions, particularly those relating to sporadic forms of disease, remain unanswered. Massively parallel sequencing technology has made significant contributions to the field, both from a diagnostic perspective for patients and, importantly, also from the perspective of disease mechanism. The importance of de novo variation in sporadic disease is a recent highlight, and the genetic link between heart and brain development has been established. Furthermore, evidence of an underlying burden of genetic variation contributing to sporadic and familial forms of CHD has been identified. Although we are still unable to identify the cause of CHD for most patients, recent findings have provided us with a much clearer understanding of the types of variants and their individual contributions and collectively mark an important milestone in our understanding of both familial and sporadic forms of disease.

Heart Failure in Pediatric Patients With Congenital Heart Disease

Heart failure (HF) is a complex clinical syndrome resulting from diverse primary and secondary causes and shared pathways of disease progression, correlating with substantial mortality, morbidity, and cost. HF in children is most commonly attributable to coexistent congenital heart disease, with different risks depending on the specific type of malformation. Current management and therapy for HF in children are extrapolated from treatment approaches in adults. This review discusses the causes, epidemiology, and manifestations of HF in children with congenital heart disease and presents the clinical, genetic, and molecular characteristics that are similar or distinct from adult HF. The objective of this review is to provide a framework for understanding rapidly increasing genetic and molecular information in the challenging context of detailed phenotyping. We review clinical and translational research studies of HF in congenital heart disease including at the genome, transcriptome, and epigenetic levels. Unresolved issues and directions for future study are presented.

Genotypic and phenotypic predictors of complete heart block and recovery of conduction after surgical repair of congenital heart disease

BACKGROUND

Complete heart block (CHB) is a major complication that occurs after congenital heart surgery. We hypothesized that genetic and clinical factors are associated with the development of postoperative CHB and recovery of atrioventricular (AV) conduction.

OBJECTIVE

The purpose of this study was to identify predictors of CHB and recovery after congenital heart surgery.

METHODS

Patients undergoing congenital heart surgery at our institution from September 2007 through June 2015 were prospectively enrolled in a parent study of postoperative arrhythmias. Patients with onset of CHB within 48 hours postoperatively were included in the study. Daily rhythm assessment was performed until demonstration of 1:1 conduction or pacemaker implantation.

RESULTS

Of 1199 subjects enrolled, 56 (4.7%) developed postoperative CHB. In multivariate analysis, preoperative digoxin exposure (odds ratio [OR] 2.4, 95% confidence interval [CI] 1.3-4.4), aortic cross-clamp time (OR 1.08, 95% CI 1.04-1.11), ventricular septal defect closure (OR 2.2, 95% CI 1.2-4.1), and a common polymorphism in the gene encoding connexin-40 (GJA5 rs10465885 TT genotype; OR 2.1, 95% CI 1.2-3.8) were independently associated with postoperative CHB. Junctional acceleration (JA) (OR 4.0, 95% CI 1.1-15.1) and intermittent conduction noted during complete AV block (OR 9.1, 95% CI 1.0-80) were independently associated with 1:1 AV conduction recovery. Use of a multivariate model including both JA and intermittent conduction demonstrated good discrimination with a positive predictive value of 86% (95% CI 67%-96%) in predicting 1:1 conduction recovery.

CONCLUSION

Preoperative factors, including a missense polymorphism in GJA5, are independently associated with increased risk for CHB. JA and intermittent conduction may prove useful in predicting recovery of AV conduction among patients with CHB after congenital heart surgery.