Background: Left ventricular noncompaction (LVNC) is a hereditary cardiomyopathy that is associated with high morbidity and mortality rates. Recently, LVNC was classified into several phenotypes including congenital heart disease (CHD). However, although LVNC and CHD are frequently observed, the role and clinical significance of genetics in these cardiomyopathies has not been fully evaluated. Therefore, we aimed to evaluate the impact on the perioperative outcomes of children with concomitant LVNC and CHD using next-generation sequencing (NGS). Methods: From May 2000 to August 2018, 53 Japanese probands with LVNC (25 males and 28 females) were enrolled and we screened 182 cardiomyopathy-associated genes in these patients using NGS. Results: The age at diagnosis of the enrolled patients ranged from 0 to 14 years (median: 0.3 months). A total of 23 patients (43.4%) were diagnosed with heart failure, 14 with heart murmur (26.4%), and 6 with cyanosis (11.3%). During the observation period, 31 patients (58.5%) experienced heart failure and 13 (24.5%) developed arrhythmias such as ventricular tachycardia, supraventricular tachycardia, and atrioventricular block. Moreover, 29 patients (54.7%) had ventricular septal defects (VSDs), 17 (32.1%) had atrial septal defects, 10 had patent ductus arteriosus (PDA), and 7 (13.2%) had Ebstein’s anomaly and double outlet right ventricle. Among the included patients, 30 underwent surgery, 19 underwent biventricular repair, and 2 underwent pulmonary artery banding, bilateral pulmonary artery banding, and PDA ligation. Overall, 30 genetic variants were identified in 28 patients with LVNC and CHD. Eight variants were detected in MYH7 and two in TPM1. Echocardiography showed lower ejection fractions and more thickened trabeculations in the left ventricle in patients with LVNC and CHD than in age-matched patients with VSDs. During follow-up, 4 patients died and the condition of 8 worsened postoperatively. The multivariable proportional hazards model showed that heart failure, LV ejection fraction of < 24%, LV end-diastolic diameter z-score of > 8.56, and noncompacted-to-compacted ratio of the left ventricular apex of > 8.33 at the last visit were risk factors for survival. Conclusions: LVNC and CHD are frequently associated with genetic abnormalities. Knowledge of the association between CHD and LVNC is important for the awareness of clinical implications during the preoperative and postoperative periods to identify the populations who are at an increased risk of additional morbidity.

Background: Tachycardia-induced cardiomyopathy (TIC) is caused by prolonged tachycardia, leading to left ventricular dilatation and systolic dysfunction with heart failure. Although TIC is more common in adults, it is rare in early infancy. Methods: Clinical testing was performed as part of medical evaluation and management. Next-generation sequencing (NGS) was conducted for a patient with TIC. A literature review on TIC was also conducted. Results: The case involved a 5-month-old infant referred to the hospital due to symptoms of heart failure lasting at least two months. The infant’s heart rate was 200 beats per minute, the left ventricular ejection fraction fell below 14%, and electrocardiograms showed atrial flutter, suggesting TIC. After cardioversion, there was no recurrence of atrial flutter, and cardiac function improved 98 days after tachycardia arrest. The NGS did not identify any pathogenic variants. The literature review identified eight early infantile cases of TIC. However, no previous reports described a case with such a prolonged duration of TIC as ours. Conclusions: This is the first report of a case of prolonged TIC in a child with the documented time to recover normal cardiac function. The improvement of cardiac function depends on the duration of TIC. Early recognition and intervention in TIC are essential to improve outcomes for infantile patients, as timely treatment offers the potential for recovery.

Background: Left ventricular hypertrophy (LVH) is a well-recognized cardiac dysfunction in infants of mothers with gestational diabetes mellitus (GDM). Left ventricular noncompaction (LVNC) is a cardiomyopathy that is morphologically characterized by numerous prominent trabeculations and deep intertrabecular recesses on cardiovascular imaging. However, there have been no case reports on neonates of mothers with GDM showing LVH and LVNC. Case presentation: A patient, with LVH of a mother with GDM, was delivered at 36 weeks of gestation. Prominent trabeculations in the LV, suggesting LVNC, instead of LVH, were apparent 1 week after birth. A heterozygous deletion variant in the MYH7 gene (NM_000257.4: c.1090T>C, p.Phe364Leu) was discovered through genetic testing using a cardiomyopathy-associated gene panel in the patient and his father and the older brother who had LVNC. The patient is now 5 years old and does not have major cardiac events, although LVNC persisted. This is the first case of LVH secondary to a mother with GDM and LVNC with a novel variant in the MYH7 gene. Conclusion: Genetic testing should be conducted to obtain an accurate outcome and medical care in a patient with LVH and subsequently prominent hypertrabeculation in the LV.

Background: Tachycardia-induced cardiomyopathy (TIC) is caused by prolonged tachycardia leading to left ventricular dilatation and systolic dysfunction with heart failure. Although TIC is more common in adult, it is rare in early infant. Methods: Clinical testing was performed as part of medical evaluation and management. Next gene se-quencing (NGS) was performed for a patient with TIC. Literature review about TIC was con-ducted. Results: The case was a 5-month-old infant referred the hospital due to symptoms with heart failure at least lasting two months. Heart rate was 200 beats per minute, left ventricular ejection fraction fell below 14%, and electrocardiograms showed atrial flutter, suggesting TIC. After cardiover-sion, there was no recurrence of atrial flutter, and cardiac function was improved at 98 days after tachycardia arrest. There were no pathogenic variants identified according to NGS. Literature review identified 8 early infantile cases with TIC reported. However, there were no previous re-ports such as our case with longer duration of TIC. Conclusions: Improvement of cardiac function depends on the duration of TIC. TIC should be considered in all patients with a dilated cardiomyopathy of uncertain origin and who have tachycardias such as atrial flutter.