Genetic Evaluation of A Nation-Wide Dutch Pediatric DCM Cohort:The Use of Genetic Testing in Risk Stratification

BACKGROUND: This study aimed to describe the current practice and results of genetic evaluation in Dutch children with dilated cardiomyopathy and to evaluate genotype-phenotype correlations that may guide prognosis. METHODS: We performed a multicenter observational study in children diagnosed with dilated cardiomyopathy, from 2010 to 2017. RESULTS: One hundred forty-four children were included. Initial diagnostic categories were idiopathic dilated cardiomyopathy in 67 children (47%), myocarditis in 23 (16%), neuromuscular in 7 (5%), familial in 18 (13%), inborn error of metabolism in 4 (3%), malformation syndrome in 2 (1%), and "other" in 23 (16%). Median follow-up time was 2.1 years [IQR 1.0-4.3]. Hundred-seven patients (74%) underwent genetic testing. We found a likely pathogenic or pathogenic variant in 38 children (36%), most often in MYH7 (n = 8). In 1 patient initially diagnosed with myocarditis, a pathogenic LMNA variant was found. During the study, 39 patients (27%) reached study endpoint (SE: all-cause death or heart transplantation). Patients with a likely pathogenic or pathogenic variant were more likely to reach SE compared with those without (hazard ratio 2.8; 95% CI 1.3-5.8, P = 0.007), while transplant-free survival was significantly lower (P = 0.006). Clinical characteristics at diagnosis did not differ between the 2 groups. CONCLUSIONS: Genetic testing is a valuable tool for predicting prognosis in children with dilated cardiomyopathy, with carriers of a likely pathogenic or pathogenic variant having a worse prognosis overall. Genetic testing should be incorporated in clinical work-up of all children with dilated cardiomyopathy regardless of presumed disease pathogenesis

Clinical Course of TGA After Arterial Switch Operation in the Current Era

Background: The number of patients with an arterial switch operation (ASO) for transposition of the great arteries (TGA) is steadily growing; limited information is available regarding the clinical course in the current era. Objectives: The purpose was to describe clinical outcome late after ASO in a national cohort, including survival, rates of (re-)interventions, and clinical events. Methods: A total of 1,061 TGA-ASO patients (median age 10.7 years [IQR: 2.0-18.2 years]) from a nationwide prospective registry with a median follow-up of 8.0 years (IQR: 5.4-8.8 years) were included. Using an analysis with age as the primary time scale, cumulative incidence of survival, (re)interventions, and clinical events were determined. Results: At the age of 35 years, late survival was 93% (95% CI: 88%-98%). The cumulative re-intervention rate at the right ventricular outflow tract and pulmonary branches was 36% (95% CI: 31%-41%). Other cumulative re-intervention rates at 35 years were on the left ventricular outflow tract (neo-aortic root and valve) 16% (95% CI: 10%-22%), aortic arch 9% (95% CI: 5%-13%), and coronary arteries 3% (95% CI: 1%-6%). Furthermore, 11% (95% CI: 6-16%) of the patients required electrophysiological interventions. Clinical events, including heart failure, endocarditis, and myocardial infarction occurred in 8% (95% CI: 5%-11%). Independent risk factors for any (re-)intervention were TGA morphological subtype (Taussig-Bing double outlet right ventricle [HR: 4.9, 95% CI: 2.9-8.1]) and previous pulmonary artery banding (HR: 1.6, 95% CI: 1.0-2.2). Conclusions: TGA-ASO patients have an excellent survival. However, their clinical course is characterized by an ongoing need for (re-)interventions, especially on the right ventricular outflow tract and the left ventricular outflow tract indicating a strict lifelong surveillance, also in adulthood.</p

Bosutinib in Resistant and Intolerant Pediatric Patients With Chronic Phase Chronic Myeloid Leukemia:Results From the Phase I Part of Study ITCC054/COG AAML1921

PURPOSE Bosutinib is approved for adults with chronic myeloid leukemia (CML): 400 mg once daily in newly diagnosed (ND); 500 mg once daily in resistant/intolerant (R/I) patients. Bosutinib has a different tolerability profile than other tyrosine kinase inhibitors (TKIs) and potentially less impact on growth (preclinical data). The primary objective of this first-in-child trial was to determine the recommended phase II dose (RP2D) for pediatric R/I and ND patients. PATIENTS AND METHODS In the phase I part of this international, open-label trial (ClinicalTrials.gov identifier: NCT04258943), children age 1-18 years with R/I (per European LeukemiaNet 2013) Ph+ CML were enrolled using a 6 + 4 design, testing 300, 350, and 400 mg/m2 once daily with food. The RP2D was the dose resulting in 0/6 or 1/10 dose-limiting toxicities (DLTs) during the first cycle and achieving adult target AUC levels for the respective indication. As ND participants were only enrolled in phase II, the ND RP2D was selected based on data from R/I patients. Results Thirty patients were enrolled; 27 were evaluable for DLT: six at 300 mg/m2, 11 at 350 mg/m2 (one DLT), and 10 at 400 mg/m2 (one DLT). The mean AUCs at 300 mg/m2, 350 mg/m2, and 400 mg/m2 were 2.20 g h/mL, 2.52 g h/mL, and 2.66 g h/mL, respectively. The most common adverse event was diarrhea (93%; ≥grade 3: 11%). Seven patients stopped because of intolerance and eight because of insufficient response. Complete cytogenetic and major molecular response to bosutinib appeared comparable with other published phase I/II trials with second-generation TKIs in children. CONCLUSION Bosutinib was safe and effective. The pediatric RP2D was 400 mg/m2 once daily (max 600 mg/d) with food in R/I patients and 300 mg/m2 once daily (max 500 mg/d) with food in ND patients, which achieved targeted exposures as per adult experience.</p

Bosutinib in Resistant and Intolerant Pediatric Patients With Chronic Phase Chronic Myeloid Leukemia:Results From the Phase I Part of Study ITCC054/COG AAML1921

PURPOSE Bosutinib is approved for adults with chronic myeloid leukemia (CML): 400 mg once daily in newly diagnosed (ND); 500 mg once daily in resistant/intolerant (R/I) patients. Bosutinib has a different tolerability profile than other tyrosine kinase inhibitors (TKIs) and potentially less impact on growth (preclinical data). The primary objective of this first-in-child trial was to determine the recommended phase II dose (RP2D) for pediatric R/I and ND patients. PATIENTS AND METHODS In the phase I part of this international, open-label trial (ClinicalTrials.gov identifier: NCT04258943), children age 1-18 years with R/I (per European LeukemiaNet 2013) Ph+ CML were enrolled using a 6 + 4 design, testing 300, 350, and 400 mg/m2 once daily with food. The RP2D was the dose resulting in 0/6 or 1/10 dose-limiting toxicities (DLTs) during the first cycle and achieving adult target AUC levels for the respective indication. As ND participants were only enrolled in phase II, the ND RP2D was selected based on data from R/I patients. Results Thirty patients were enrolled; 27 were evaluable for DLT: six at 300 mg/m2, 11 at 350 mg/m2 (one DLT), and 10 at 400 mg/m2 (one DLT). The mean AUCs at 300 mg/m2, 350 mg/m2, and 400 mg/m2 were 2.20 g h/mL, 2.52 g h/mL, and 2.66 g h/mL, respectively. The most common adverse event was diarrhea (93%; ≥grade 3: 11%). Seven patients stopped because of intolerance and eight because of insufficient response. Complete cytogenetic and major molecular response to bosutinib appeared comparable with other published phase I/II trials with second-generation TKIs in children. CONCLUSION Bosutinib was safe and effective. The pediatric RP2D was 400 mg/m2 once daily (max 600 mg/d) with food in R/I patients and 300 mg/m2 once daily (max 500 mg/d) with food in ND patients, which achieved targeted exposures as per adult experience.</p

Determinants of exercise limitation in contemporary paediatric Fontan patients with an extra cardiac conduit

Background: Although various determinants of exercise limitation in Fontan patients have been studied, most research has been performed in patients who underwent different surgical procedures with differing haemodynamic characteristics. The aim of the current study was to evaluate non-invasively measured cardiovascular parameters and their influence on exercise performance in paediatric Fontan patients with an extracardiac conduit and moderate-good systolic ventricular function. Methods: Fontan patients, between 8 and 18 years of age, with moderate to good systolic ventricular function and an extracardiac conduit were included. Exercise performance and cardiovascular assessment, comprising echocardiography, aortic stiffness measurement and ambulatory measurement of cardiac autonomous nervous activity were performed on the same day. Healthy subjects served as controls. Results: Thirty-six Fontan patients (age 14.0 years) and thirty-five healthy subjects (age 12.8 years) were included. Compared to controls, Fontan patients had reduced diastolic ventricular function and increased arterial stiffness. No differences were found in heart rate (HR) and cardiac parasympathetic nervous activity. In Fontan patients, maximal as well as submaximal exercise capacity was impaired, with the percentage of predicted capacity ranging between 54 and 72%. Chronotropic competence, however, was good with a peak HR of 174 (94% of predicted). Lower maximal and submaximal exercise capacity was correlated with a higher HR at rest, higher pulse wave velocity of the aorta and a lower ratio of early and late diastolic flow velocity. Conclusion: Contemporary paediatric Fontan patients have an impaired exercise capacity with preserved chronotropic competence. Exercise performance correlates with heart rate at rest, diastolic function and aortic stiffness

Does Repeated Measurement of a 6-Min Walk Test Contribute to Risk Prediction in Children with Dilated Cardiomyopathy?

A single 6-min walk test (6MWT) can be used to identify children with dilated cardiomyopathy (DCM) with a high risk of death or heart transplantation. To determine if repeated 6MWT has added value in addition to a single 6MWT in predicting death or heart transplantation in children with DCM. Prospective multicenter cohort study including ambulatory DCM patients ≥ 6 years. A 6MWT was performed 1 to 4 times per year. The distance walked was expressed as percentage of predicted (6MWD%). We compared the temporal evolution of 6MWD% in patients with and without the study endpoint (SE: all-cause death or heart transplantation), using a linear mixed effects model. In 57 patients, we obtained a median of 4 (IQR 2–6) 6MWTs per patient during a median of 3.0 years of observation (IQR 1.5–5.1). Fourteen patients reached a SE (3 deaths, 11 heart transplantations). At any time during follow-up, the average estimate of 6MWD% was significantly lower in patients with a SE compared to patients without a SE. In both patients groups, 6MWD% remained constant over time. An absolute 1% lower 6MWD% was associated with an 11% higher risk (hazard) of the SE (HR 0.90, 95% CI 0.86–0.95 p < 0.001). Children with DCM who died or underwent heart transplantation had systematically reduced 6MWD%. The performance of all patients was stable over time, so repeated measurement of 6MWT within this time frame had little added value over a single test

Clinical Course of TGA After Arterial Switch Operation in the Current Era

Background: The number of patients with an arterial switch operation (ASO) for transposition of the great arteries (TGA) is steadily growing; limited information is available regarding the clinical course in the current era. Objectives: The purpose was to describe clinical outcome late after ASO in a national cohort, including survival, rates of (re-)interventions, and clinical events. Methods: A total of 1,061 TGA-ASO patients (median age 10.7 years [IQR: 2.0-18.2 years]) from a nationwide prospective registry with a median follow-up of 8.0 years (IQR: 5.4-8.8 years) were included. Using an analysis with age as the primary time scale, cumulative incidence of survival, (re)interventions, and clinical events were determined. Results: At the age of 35 years, late survival was 93% (95% CI: 88%-98%). The cumulative re-intervention rate at the right ventricular outflow tract and pulmonary branches was 36% (95% CI: 31%-41%). Other cumulative re-intervention rates at 35 years were on the left ventricular outflow tract (neo-aortic root and valve) 16% (95% CI: 10%-22%), aortic arch 9% (95% CI: 5%-13%), and coronary arteries 3% (95% CI: 1%-6%). Furthermore, 11% (95% CI: 6-16%) of the patients required electrophysiological interventions. Clinical events, including heart failure, endocarditis, and myocardial infarction occurred in 8% (95% CI: 5%-11%). Independent risk factors for any (re-)intervention were TGA morphological subtype (Taussig-Bing double outlet right ventricle [HR: 4.9, 95% CI: 2.9-8.1]) and previous pulmonary artery banding (HR: 1.6, 95% CI: 1.0-2.2). Conclusions: TGA-ASO patients have an excellent survival. However, their clinical course is characterized by an ongoing need for (re-)interventions, especially on the right ventricular outflow tract and the left ventricular outflow tract indicating a strict lifelong surveillance, also in adulthood.</p

Clinical Course of TGA After Arterial Switch Operation in the Current Era

Background: The number of patients with an arterial switch operation (ASO) for transposition of the great arteries (TGA) is steadily growing; limited information is available regarding the clinical course in the current era. Objectives: The purpose was to describe clinical outcome late after ASO in a national cohort, including survival, rates of (re-)interventions, and clinical events. Methods: A total of 1,061 TGA-ASO patients (median age 10.7 years [IQR: 2.0-18.2 years]) from a nationwide prospective registry with a median follow-up of 8.0 years (IQR: 5.4-8.8 years) were included. Using an analysis with age as the primary time scale, cumulative incidence of survival, (re)interventions, and clinical events were determined. Results: At the age of 35 years, late survival was 93% (95% CI: 88%-98%). The cumulative re-intervention rate at the right ventricular outflow tract and pulmonary branches was 36% (95% CI: 31%-41%). Other cumulative re-intervention rates at 35 years were on the left ventricular outflow tract (neo-aortic root and valve) 16% (95% CI: 10%-22%), aortic arch 9% (95% CI: 5%-13%), and coronary arteries 3% (95% CI: 1%-6%). Furthermore, 11% (95% CI: 6-16%) of the patients required electrophysiological interventions. Clinical events, including heart failure, endocarditis, and myocardial infarction occurred in 8% (95% CI: 5%-11%). Independent risk factors for any (re-)intervention were TGA morphological subtype (Taussig-Bing double outlet right ventricle [HR: 4.9, 95% CI: 2.9-8.1]) and previous pulmonary artery banding (HR: 1.6, 95% CI: 1.0-2.2). Conclusions: TGA-ASO patients have an excellent survival. However, their clinical course is characterized by an ongoing need for (re-)interventions, especially on the right ventricular outflow tract and the left ventricular outflow tract indicating a strict lifelong surveillance, also in adulthood.</p