Australian National Standards of Care for Childhood-onset Heart Disease (CoHD Standards). 1st Edition.

These first Australian National Standards of Care for Childhood-onset Heart Disease (CoHD Standards) have been developed to inform the healthcare requirements for CoHD services and enable all Australian patients, families and carers impacted by CoHD (paediatric CoHD and adult congenital heart disease [ACHD]) to live their best and healthiest lives. The CoHD Standards are designed to provide the clarity and certainty required for healthcare services to deliver excellent, comprehensive, inclusive, and equitable CoHD care across Australia for patients, families and carers, and offer an iterative roadmap to the future of these services. The CoHD Standards provide a framework for excellent CoHD care, encompassing key requirements and expectations for whole-of-life, holistic and connected healthcare service delivery. The CoHD Standards should be implemented in health services in conjunction with the National Safety and Quality Health Service Standards developed by the Australian Commission on Safety and Quality in Health Care. All healthcare services should comply with the CoHD Standards, as well as working to their organisation's or jurisdiction's agreed clinical governance framework, to guide the implementation of structures and processes that support safe care.

TBX20 loss-of-function variants in families with left ventricular non-compaction cardiomyopathy.

TBX20 encodes a cardiac transcription factor that is associated with atrial septal defects. Recent studies implicate loss-of-function TBX20 variants with left ventricular non-compaction cardiomyopathy (LVNC), although clinical and genetic data in families are limited. We report four families with TBX20 loss-of-function variants that segregate with LVNC. Genetic testing using genome or exome sequencing was performed in index cases, variants were validated with Sanger sequencing, and cascade genetic testing was performed in family members. A multi-exon deletion, small deletion, essential splice site variant and nonsense variant in TBX20 were found in four families. The index cases in two families were symptomatic children with identical congenital heart diseases and LVNC who developed different cardiomyopathy phenotypes with one developing heart failure requiring transplantation. In another family, the child index case had LVNC and congestive heart failure requiring heart transplantation. In the fourth family, the index case was a symptomatic adult with LVNC. In all families, the variants segregated in relatives with isolated LVNC, or with congenital heart disease or cardiomyopathy. Family members displayed a clinical spectrum from asymptomatic to severe presentations including heart failure. Our data strengthen TBX20 loss-of-function variants as a rare cause of LVNC and support TBX20 inclusion in genetic testing of LVNC.

The burden of splice-disrupting variants in inherited heart disease and unexplained sudden cardiac death.

There is an incomplete understanding of the burden of splice-disrupting variants in definitively associated inherited heart disease genes and whether these genes can amplify from blood RNA to support functional confirmation of splicing outcomes. We performed burden testing of rare splice-disrupting variants in people with inherited heart disease and sudden unexplained death compared to 125,748 population controls. ClinGen definitively disease-associated inherited heart disease genes were amplified using RNA extracted from fresh blood, derived cardiomyocytes, and myectomy tissue. Variants were functionally assessed and classified for pathogenicity. We found 88 in silico-predicted splice-disrupting variants in 128 out of 1242 (10.3%) unrelated participants. There was an excess burden of splice-disrupting variants in PKP2 (5.9%), FLNC (2.7%), TTN (2.8%), MYBPC3 (8.2%) and MYH7 (1.3%), in distinct cardiomyopathy subtypes, and KCNQ1 (3.6%) in long QT syndrome. Blood RNA supported the amplification of 21 out of 31 definitive disease-associated inherited heart disease genes. Our functional studies confirmed altered splicing in six variants. Eleven variants of uncertain significance were reclassified as likely pathogenic based on functional studies and six were used for cascade genetic testing in 12 family members. Our study highlights that splice-disrupting variants are a significant cause of inherited heart disease, and that analysis of blood RNA confirms splicing outcomes and supports variant pathogenicity classification.

Risk of Sudden Death in Patients With RASopathy Hypertrophic Cardiomyopathy.

BACKGROUND: Genetic defects in the RAS/mitogen-activated protein kinase pathway are an important cause of hypertrophic cardiomyopathy (RAS-HCM). Unlike primary HCM (P-HCM), the risk of sudden cardiac death (SCD) and long-term survival in RAS-HCM are poorly understood. OBJECTIVES: The study's objective was to compare transplant-free survival, incidence of SCD, and implantable cardioverter-defibrillator (ICD) use between RAS-HCM and P-HCM patients. METHODS: In an international, 21-center cohort study, we analyzed phenotype-positive pediatric RAS-HCM (n = 188) and P-HCM (n = 567) patients. The between-group differences in cumulative incidence of all outcomes from first evaluation were compared using Gray's tests, and age-related hazard of all-cause mortality was determined. RESULTS: RAS-HCM patients had a lower median age at diagnosis compared to P-HCM (0.9 years [IQR: 0.2-5.0 years] vs 9.8 years [IQR: 2.0-13.9 years], respectively) (P < 0.001). The 10-year cumulative incidence of SCD from first evaluation was not different between RAS-HCM and P-HCM (4.7% vs 4.2%, respectively; P = 0.59). The 10-year cumulative incidence of nonarrhythmic deaths or transplant was higher in RAS-HCM compared with P-HCM (11.0% vs 5.4%, respectively; P = 0.011). The 10-year cumulative incidence of ICD insertions, however, was 5-fold lower in RAS-HCM compared with P-HCM (6.9% vs 36.6%; P < 0.001). Nonarrhythmic deaths occurred primarily in infancy and SCD primarily in adolescence. CONCLUSIONS: RAS-HCM was associated with a higher incidence of nonarrhythmic death or transplant but similar incidence of SCD as P-HCM. However, ICDs were used less frequently in RAS-HCM compared to P-HCM. In addition to monitoring for heart failure and timely consideration of advanced heart failure therapies, better risk stratification is needed to guide ICD practices in RAS-HCM.

Long-term Outcomes of Transatrial-Transpulmonary Repair of Tetralogy of Fallot With Anomalous Coronary Arteries.

Repair of tetralogy of Fallot (TOF) can be complicated by the presence of an anomalous coronary artery (ACA) crossing the right ventricular outflow tract (RVOT). This study sought to evaluate the late outcomes of a policy of transatrial-transpulmonary repair for this condition. The transatrial-transpulmonary approach was used in 864 consecutive TOF repairs between 1993 and 2018 at a single institution, of which 55 (6%) patients had an ACA. Nineteen (35%,19/55) patients underwent prior palliation. Late survival and freedom from reoperations were compared with the general cohort of 809 patients who underwent complete repair during the same period. Early mortality was 2% (1/55). Median follow-up was 15.6 years. Late mortality was 6% (3/54). Absence of a preoperative diagnosis of ACA was not a risk factor for worse outcomes in terms of late re-interventions, acute coronary syndrome, residual RVOT gradient, and late mortality. Survival was 91% (95% confidence interval [CI]: 77-96%) at 20 years and was comparable to the general TOF cohort (95%, 95% CI: 90-98%, P = 0.12). Actuarial freedom from any re-intervention was 46% (95% CI: 27-62%) at 20 years, which was also comparable to the general cohort (31%, 95% CI: 20-42%, P = 0.19). The presence of an ACA does not appear to affect late survival or re-intervention rates in patients undergoing transatrial-transpulmonary repair of TOF.

The Prevalence and Association of Exercise Test Abnormalities With Sudden Cardiac Death and Transplant-Free Survival in Childhood Hypertrophic Cardiomyopathy.

BACKGROUND: Hypertrophic cardiomyopathy (HCM) can be associated with an abnormal exercise response. In adults with HCM, abnormal results on exercise stress testing are predictive of heart failure outcomes. Our goal was to determine whether an abnormal exercise response is associated with adverse outcomes in pediatric patients with HCM. METHODS: In an international cohort study including 20 centers, phenotype-positive patients with primary HCM who were <18 years of age at diagnosis were included. Abnormal exercise response was defined as a blunted blood pressure response and new or worsened ST- or T-wave segment changes or complex ventricular ectopy. Sudden cardiac death (SCD) events were defined as a composite of SCD and aborted sudden cardiac arrest. Using Kaplan-Meier survival, competing outcomes, and Cox regression analyses, we analyzed the association of abnormal exercise test results with transplant and SCD event-free survival. RESULTS: Of 724 eligible patients, 630 underwent at least 1 exercise test. There were no major differences in clinical characteristics between those with or without an exercise test. The median age at exercise testing was 13.8 years (interquartile range, 4.7 years); 78% were male and 39% were receiving beta-blockers. A total of 175 (28%) had abnormal test results. Patients with abnormal test results had more severe septal hypertrophy, higher left atrial diameter z scores, higher resting left ventricular outflow tract gradient, and higher frequency of myectomy compared with participants with normal test results (P<0.05). Compared with normal test results, abnormal test results were independently associated with lower 5-year transplant-free survival (97% versus 88%, respectively; P=0.005). Patients with exercise-induced ischemia were most likely to experience all-cause death or transplant (hazard ratio, 4.86 [95% CI, 1.69-13.99]), followed by those with an abnormal blood pressure response (hazard ratio, 3.19 [95% CI, 1.32-7.71]). Exercise-induced ischemia was also independently associated with lower SCD event-free survival (hazard ratio, 3.32 [95% CI, 1.27-8.70]). Exercise-induced ectopy was not associated with survival. CONCLUSIONS: Exercise abnormalities are common in childhood HCM. An abnormal exercise test result was independently associated with lower transplant-free survival, especially in those with an ischemic or abnormal blood pressure response with exercise. Exercise-induced ischemia was also independently associated with SCD events. These findings argue for routine exercise testing in childhood HCM as part of ongoing risk assessment.

Long-term Outcomes of Staged Complete Repair of Pulmonary Atresia With Ventricular Septal Defect.

BACKGROUND: The optimal strategy for pulmonary atresia with ventricular septal defect (PA-VSD) without major aortopulmonary collateral arteries is yet to be defined. It remains unclear how primary complete repair compares with staged repair. METHODS: This study reviewed the records of 107 patients with PA-VSD who were managed with systemic-to-pulmonary shunts from February 1989 to November 2019. Tables presenting summary statistics of patient and surgical data and Kaplan-Meier curves showing repair, mortality, and reoperation were created. Logistic regression analysis was performed to identify risk factors for repair, morbidity, and mortality. RESULTS: A total of 91 (85%) patients achieved complete repair at a median age of 1 year (interquartile range [IQR], 8-20 months). Survival was as follows: 97 (90%) patients at 6 months, 91 (85%) at 20 months, and 87 (81%) at 10 years. A shunt diameter of 3.5 mm or less (P = .006) and shunt after 2009 (P < .001) were associated with earlier progression to complete repair. A shunt diameter of 3.5 mm or less was an independent risk factor for interstage morbidity (hazard ratio, 4.5; IQR, 1.1-18.5; P = .039), but it was not associated with complete repair (P = .75) or mortality (P = .62). The median follow-up period was 10.5 years (IQR, 3.6-18.8 years) from birth. CONCLUSIONS: The complete repair and long-term survival rates of staged PA-VSD repair are high. The use of smaller shunts has resulted in earlier complete repair and is associated with increased risk of morbidity but not mortality.

Long-term outcomes of staged repair of tetralogy of Fallot.

BACKGROUND: The optimal management strategy for symptomatic young infants with tetralogy of Fallot (TOF) is yet to be determined. We aimed to evaluate the long-term outcomes of a staged approach with initial shunt palliation followed by complete repair. METHODS: Between January 1993 and July 2021, 160 children with TOF underwent a systemic-to-pulmonary shunt at our institution, including 65 neonates (41%). The mean duration of follow-up was 12.3 ± 8.1 years. RESULTS: Hospital mortality was 3% (4 of 160), all occurring in patients with a shunt size-to-weight ratio ≥1.2 mm/kg. Composite morbidity-defined as cardiac arrest, postoperative mechanical circulatory support, or unplanned reoperation-occurred in 21% (33 of 160). On multivariable analysis, a shunt size-to-weight ratio ≥1.2 mm/kg and prematurity were independent predictors of composite morbidity. Interstage mortality was 3% (4 of 156). A limited transannular patch was used in 75% (113 of 150) of TOF repairs. Actuarial survival at 20 years after shunt was 90% (95% confidence interval [CI], 79%-95%). Actuarial freedom from reinterventions at 20 years after TOF repair was 40% (95% CI, 28%-52%). Neonates had comparable composite morbidity, mortality, and late risk of reinterventions to older children. CONCLUSIONS: Staged repair of TOF in symptomatic young infants results in low mortality but high rates of reinterventions at long-term follow-up. A shunt size-to-weight ratio ≥1.2 mm/kg is a significant risk factor for mortality and morbidity prior to complete repair. Neonates undergoing shunt insertion have comparable outcomes to older children.

Genetic Basis of Childhood Cardiomyopathy.

BACKGROUND: The causes of cardiomyopathy in children are less well described than in adults. We evaluated the clinical diagnoses and genetic causes of childhood cardiomyopathy and outcomes of cascade genetic testing in family members. METHODS: We recruited children from a pediatric cardiology service or genetic heart diseases clinic. We performed Sanger, gene panel, exome or genome sequencing and classified variants for pathogenicity using American College of Molecular Genetics and Genomics guidelines. RESULTS: Cardiomyopathy was diagnosed in 221 unrelated children aged ≤18 years. Children mostly had hypertrophic cardiomyopathy (n=98, 44%) or dilated cardiomyopathy (n=89, 40%). The highest genetic testing diagnostic yields were in restrictive cardiomyopathy (n=16, 80%) and hypertrophic cardiomyopathy (n=65, 66%), and lowest in dilated cardiomyopathy (n=26, 29%) and left ventricular noncompaction (n=3, 25%). Pathogenic variants were primarily found in genes encoding sarcomere proteins, with TNNT2 and TNNI3 variants associated with more severe clinical outcomes. Ten children (4.5%) had multiple pathogenic variants. Genetic test results prompted review of clinical diagnosis in 14 families with syndromic, mitochondrial or metabolic gene variants. Cascade genetic testing in 127 families confirmed 24 de novo variants, recessive inheritance in 8 families, and supported reclassification of 12 variants. CONCLUSIONS: Genetic testing of children with cardiomyopathy supports a precise clinical diagnosis, which may inform prognosis.

Long-term outcomes of primary aortic valve repair for isolated congenital aortic stenosis in children.

OBJECTIVE: We aimed to assess the long-term outcomes of children with isolated congenital aortic stenosis who underwent primary aortic valve repair. METHODS: Records of all children (n = 111) with isolated congenital aortic stenosis who underwent primary aortic valve repair between 1980 and 2016 were reviewed. An optimal operative outcome consisted of a residual left ventricular outflow tract peak systolic gradient <35 mm Hg and trivial or less aortic insufficiency. RESULTS: Median age at surgery was 0.4 years (interquartile range, 1 month-7.9 years) and median weight at surgery was 7.0 kg (interquartile range, 3.7-25.0 kg). Fifty-two patients (46.8%; 52/111) underwent aortic valve repair with the use of patch material. Early mortality was 0.9% (1/111). Late mortality was 0.9% (1/110). Freedom from aortic valve reoperation was 52.1% (95% CI, 38.7-63.8) at 10 years. Freedom from aortic valve replacement was 67.9% (95% CI, 55.4-77.5) at 10 years. An optimal outcome was achieved in 48 patients (43.2%; 48/111). At 10 years, freedom from aortic valve reoperation was 78.2% (95% CI, 63.1-87.8) in patients with an optimal outcome, compared with 39.4% (95% CI, 22.8-55.6) in those with a suboptimal outcome (P = .03). Tricuspid aortic valve was associated with a suboptimal outcome (P = .01). CONCLUSIONS: Aortic valve repair achieves relief of congenital aortic stenosis with very low early mortality and excellent long-term survival, even in neonates. Although nearly half of the patients required aortic valve reoperation by 10 years, two-thirds of the patients remain free from aortic valve replacement. An optimal outcome was more commonly achieved with bicuspid aortic valves compared with tricuspid aortic valves.

Outcomes of the arterial switch operation in patients with inverted coronary artery anatomy.

OBJECTIVE: Patients undergoing the arterial switch operation (ASO) with inverted coronary anatomy represent a technical challenge. We sought to determine the long-term outcomes of patients with inverted coronary anatomy who underwent an ASO. METHODS: A retrospective analysis of patients who underwent an ASO with inverted coronary anatomy at a single institution was performed and comparison was made between patients with inverted and normal coronary anatomy. RESULTS: There were 43 (5.1% [43 out of 844]) patients with inverted coronary anatomy. Twenty patients (46.5% [20 out of 43]) had a right coronary artery that arises from sinus 1 and the left anterior descending and circumflex coronaries arise from sinus 2 anatomy and 23 (53.5% [23 out of 43]) patients with right coronary artery that arises from sinus 1 and gives rise to the left anterior descending with the circumflex coronaries arising from sinus 2. Median follow-up was 17 years (interquartile range, 12-21 years). Overall early mortality was 7.0% (3 out of 43) compared with 3.1% (17 out of 556) in patients with normal coronary anatomy undergoing operation over the same time period (P = .17). There were 2 (10% [2 out of 20]) early deaths in the right coronary artery that arises from sinus 1 and gives rise to the left anterior descending with the circumflex coronaries arising from sinus 2 group and 1 (4.3% [1 out of 23]) early death in the right coronary artery that arises from sinus 1 and the left anterior descending and circumflex coronaries arise from sinus 2 group. There was 1 late death occurring at 40 days after ASO. Nine (23% [9 out of 39]) patients had 15 reinterventions occurring at median 3.6 years (interquartile range, 1.1-8.2 years). The most common cause of reintervention was main or branch pulmonary artery stenosis (15% [6 out of 39]). Freedom from reintervention was 78% (95% CI, 68%-93%) and 75% (95% CI, 56%-86%) at 10 and 15 years, respectively. At final follow-up, all surviving local patients except 1 was in New York Heart Association functional class I. CONCLUSIONS: Patients with inverted coronary anatomy who underwent an ASO had a higher mortality but this was not statistically significant. However, there were no coronary reinterventions in survivors.

Outcomes of aortic valve repair in children resulting in bicuspid anatomy: Is there a need for tricuspidization?

OBJECTIVE: We aimed to assess outcomes after aortic valve repair leading to bicuspid valve anatomy in children. METHODS: This is a retrospective study of patients who underwent aortic valve repair with creation/preservation of bicuspid aortic valve anatomy or tricuspidization of bicuspid valves between 1980 and 2016. RESULTS: Overall, 127 patients underwent bicuspid repair. Median age was 0.73 years (interquartile range, 0.1-8.9), and median weight was 8.15 kg (interquartile range, 3.9-31.7). The cohort included 22.8% neonates (n = 29), 28.3% infants (n = 36), and 48.8% children (n = 62). Repair was performed without a patch in 54.3% (n = 69). Survival at 10 years was 94.8% (95% confidence interval, 87.5-97.85). Freedom from aortic valve reoperation at 5 and 10 years was 79.9% (95% confidence interval, 71.2-86.2) and 65.6% (95% confidence interval, 53.4-75.3), respectively. Re-repair was undertaken in 53.7% (22/41). Freedom from aortic valve replacement at 5 and 10 years was 90.3% (95% confidence interval, 83.1-94.5) and 75.8% (95% confidence interval, 63-84.7), respectively. Risk factors for reoperation were age less than 1 year, unicuspid valve, and the presence of Shone complex and concomitant aortic arch repair. There were 107 patients (107/127, 84.25%) with preoperative bicuspid aortic valve morphology that was preserved. They were compared with a separate cohort of 44 patients who underwent tricuspidization of bicuspid aortic valve during the same period. There was no difference in survival or freedom from aortic valve reoperation. However, freedom from aortic valve replacement was lower after tricuspidization with 49.7% (95% confidence interval, 26.3-69.3) versus 75.8% (95% confidence interval, 62.1-85.1) after 10 years (P = .0118). CONCLUSIONS: Aortic valve repair leading to bicuspid valve anatomy in children has satisfactory long-term results. Reoperation remains common, but the need for early valve replacement can be effectively delayed.

Whole genome sequencing delineates regulatory, copy number, and cryptic splice variants in early onset cardiomyopathy.

Cardiomyopathy (CMP) is a heritable disorder. Over 50% of cases are gene-elusive on clinical gene panel testing. The contribution of variants in non-coding DNA elements that result in cryptic splicing and regulate gene expression has not been explored. We analyzed whole-genome sequencing (WGS) data in a discovery cohort of 209 pediatric CMP patients and 1953 independent replication genomes and exomes. We searched for protein-coding variants, and non-coding variants predicted to affect the function or expression of genes. Thirty-nine percent of cases harbored pathogenic coding variants in known CMP genes, and 5% harbored high-risk loss-of-function (LoF) variants in additional candidate CMP genes. Fifteen percent harbored high-risk regulatory variants in promoters and enhancers of CMP genes (odds ratio 2.25, p = 6.70 × 10-7 versus controls). Genes involved in α-dystroglycan glycosylation (FKTN, DTNA) and desmosomal signaling (DSC2, DSG2) were most highly enriched for regulatory variants (odds ratio 6.7-58.1). Functional effects were confirmed in patient myocardium and reporter assays in human cardiomyocytes, and in zebrafish CRISPR knockouts. We provide strong evidence for the genomic contribution of functionally active variants in new genes and in regulatory elements of known CMP genes to early onset CMP.

Long-term outcomes of the arterial switch operation.

OBJECTIVES: The arterial switch operation (ASO) has excellent early outcomes in the modern era. We sought to determine the long-term outcomes in patients who underwent an ASO at a single institution. METHODS: Patients who underwent an ASO between 1983 and 2015 were identified from the hospital database and retrospectively reviewed using hospital records. RESULTS: From 1983 to 2015, 844 patients with a biventricular circulation underwent an ASO. There were 28 (3.3%, 28/844) early deaths. Follow-up was available for 94% (729/774) of local patients after hospital discharge. Median follow-up was 15 years (interquartile range, 8-20 years). There were 187 (26%, 187/729) patients with more than 20 years of follow-up and 95 (13%, 95/729) patients with more than 25 years of follow-up. Overall survival was 95% (95% confidence interval [CI], 94%-97%) at 10 and 25 years after the ASO. At 25 years after ASO, freedom from overall reintervention was 77% (95% CI, 73%-81%), freedom from reoperation on the neoaortic root or neoaortic valve was 92% (95% CI, 88%-95%), and freedom from coronary reoperation was 99% (95% CI, 98%-99.7%). Left ventricular (LV) systolic function was normal in 595 of 609 (98%) of patients who had LV function quantified at latest follow-up. Of the 95 patients with more than 25 years of follow-up after ASO, 6 (6.3%) had at least moderate neoaortic valve regurgitation (AR) and 8 (8.4%) had undergone replacement of the neoaortic valve. CONCLUSIONS: Overall, survivors of ASO have excellent late survival and normal LV systolic function into adult life. However, AR and reoperation on the neoaortic valve remains an issue for older patients.

PPA2-associated sudden cardiac death: extending the clinical and allelic spectrum in 20 new families.

PURPOSE: Biallelic hypomorphic variants in PPA2, encoding the mitochondrial inorganic pyrophosphatase 2 protein, have been recently identified in individuals presenting with sudden cardiac death, occasionally triggered by alcohol intake or a viral infection. Here we report 20 new families harboring PPA2 variants. METHODS: Synthesis of clinical and molecular data concerning 34 individuals harboring five previously reported PPA2 variants and 12 novel variants, 11 of which were functionally characterized. RESULTS: Among the 34 individuals, only 6 remain alive. Twenty-three died before the age of 2 years while five died between 14 and 16 years. Within these 28 cases, 15 died of sudden cardiac arrest and 13 of acute heart failure. One case was diagnosed prenatally with cardiomyopathy. Four teenagers drank alcohol before sudden cardiac arrest. Progressive neurological signs were observed in 2/6 surviving individuals. For 11 variants, recombinant PPA2 enzyme activities were significantly decreased and sensitive to temperature, compared to wild-type PPA2 enzyme activity. CONCLUSION: We expand the clinical and mutational spectrum associated with PPA2 dysfunction. Heart failure and sudden cardiac arrest occur at various ages with inter- and intrafamilial phenotypic variability, and presentation can include progressive neurological disease. Alcohol intake can trigger cardiac arrest and should be strictly avoided.

Characterization of clinically relevant copy-number variants from exomes of patients with inherited heart disease and unexplained sudden cardiac death.

PURPOSE: Copy-number variant (CNV) analysis is increasingly performed in genetic diagnostics. We leveraged recent gene curation efforts and technical standards for interpretation and reporting of CNVs to characterize clinically relevant CNVs in patients with inherited heart disease and sudden cardiac death. METHODS: Exome sequencing data were analyzed for CNVs using eXome-Hidden Markov Model tool in 48 established disease genes. CNV breakpoint junctions were characterized. CNVs were classified using the American College of Medical Genetics and Genomics technical standards. RESULTS: We identified eight CNVs in 690 unrelated probands (1.2%). Characterization of breakpoint junctions revealed nonhomologous end joining was responsible for four deletions, whereas one duplication was caused by nonallelic homologous recombination between duplicated sequences in MYH6 and MYH7. Identifying the precise breakpoint junctions determined the genomic involvement and proved useful for interpreting the clinical relevance of CNVs. Three large deletions involving TTN, MYBPC3, and KCNH2 were classified as pathogenic in three patients. Haplotype analysis of a deletion in ACTN2, found in two families, suggests the deletion was caused by an ancestral event. CONCLUSION: CNVs infrequently cause inherited heart diseases and should be investigated when standard genetic testing does not reveal a genetic diagnosis.

Rare Association of an Intramural Coronary Artery and Truncus Arteriosus.

The association of truncus arteriosus (TA) and an intramural coronary artery is rare. Seven (7) patients had TA and an intramural coronary artery at the Royal Children's Hospital, Melbourne between 1996 and 2018. Four (4) patients underwent concomitant unroofing of their intramural coronary artery. One (1) patient who did not undergo concomitant unroofing had a cardiac arrest on postoperative day 1 and subsequently underwent reoperation for coronary unroofing. Given the potential for serious complications, patients with TA and an intramural coronary artery may benefit from coronary unroofing with creation of a generous neo-ostium.