The SARS-CoV-2 (COVID-19) pandemic has challenged our initial predictions of its ramifications, both short and long term. Cardiovascular manifestations of COVID-19 in children remain a topic of investigation as literature is lacking. We describe new onset atrial fibrillation in a child with a history of COVID-19 infection. Understanding of cardiogenic effects of COVID-19 can help minimise the delay in diagnosis.

Background: Holt–Oram syndrome is characterised by CHD and limb anomalies. Mutations in TBX5 gene, encoding the T-box transcription factor, are responsible for the development of Holt–Oram syndrome, but such mutations are variably detected in 30–75% of patients. Methods: Clinically diagnosed eight Holt–Oram syndrome patients from six families were evaluated the clinical characteristics, focusing on the cardiac manifestations, in particular, and molecular aetiologies. In addition to the investigation of the mutation of TBX5, SALL4, NKX2.5, and GATA4 genes, which are known to regulate cardiac development by physically and functionally interacting with TBX5, were also analyzed. Multiple ligation-dependent probe amplification analysis was performed to detect exonic deletion and duplication mutations in these genes. Results: All included patients showed cardiac septal defects and upper-limb anomalies. Of the eight patients, seven underwent cardiac surgery, and four suffered from conduction abnormalities such as severe sinus bradycardia and complete atrioventricular block. Although our patients showed typical clinical findings of Holt–Oram syndrome, only three distinct TBX5 mutations were detected in three families: one nonsense, one splicing, and one missense mutation. No new mutations were identified by testing SALL4, NKX2.5, and GATA4 genes. Conclusions: All Holt–Oram syndrome patients in this study showed cardiac septal anomalies. Half of them showed TBX5 gene mutations. To understand the genetic causes for inherited CHD such as Holt–Oram syndrome is helpful to take care of the patients and their families. Further efforts with large-scale genomic research are required to identify genes responsible for cardiac manifestations or genotype–phenotype relation in Holt–Oram syndrome.

Acquired complete atrioventricular block that is caused by infectious myocarditis is usually transient and has a favourable outcome. We report the case of a 15-year-old girl who had complete infra-Hisian atrioventricular block due to adeno viral myocarditis and received a permanent pacemaker at the age of 10 months. The pacemaker lost its function at the age of 7 years. However, she experienced a late recurrence of complete atrioventricular block 10 years later. Complete atrioventricular block is rarely recovered if it persisted for 2 weeks. Even in the patients with late recovery, long-term follow-up and pacemaker therapy are still needed.