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Hypertrophic cardiomyopathy (HCM), a common cardiomyopathy in children, is an important cause of morbidity and mortality. Early recognition and appropriate management are important. An electrocardiogram (ECG) is often used as a screening tool in children to detect heart disease. The ECG patterns in children with HCM are not well described.ECGs collected from an international cohort of children, and adolescents (≤ 21 years) with HCM were reviewed. 482 ECGs met inclusion criteria. Age ranged from 1 day to 21 years, median 13 years. Of the 482 ECGs, 57 (12%) were normal. The most common abnormalities noted were left ventricular hypertrophy (LVH) in 108/482 (22%) and biventricular hypertrophy (BVH) in 116/482 (24%) Of the patients with LVH/BVH (n = 224), 135 (60%) also had a strain pattern (LVH in 83, BVH in 52). Isolated strain pattern (in the absence of criteria for hypertrophy) was seen in 43/482 (9%). Isolated pathologic Q waves were seen in 71/482 (15%). Pediatric HCM, 88% have an abnormal ECG. The most common ECG abnormalities were LVH or BVH with or without strain. Strain pattern without hypertrophy and a pathologic Q wave were present in a significant proportion (24%) of patients. Thus, a significant number of children with HCM have ECG abnormalities that are not typical for "hypertrophy". The presence of the ECG abnormalities described above in a child should prompt further examination with an echocardiogram to rule out HCM., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Obesity is associated with additional left ventricular hypertrophy (LVH) in adults with hypertrophic cardiomyopathy (HCM). It is not known whether obesity can lead to further LVH in children with HCM. Echocardiographic LV dimensions were determined in 504 children with HCM. Measurements of interventricular septal thickness (IVST) and posterior wall thickness (PWT), and patients' weight and height were recorded. Obesity was defined as a body mass index (BMI) ≥ 99th percentile for age and sex. IVST data was available for 498 and PWT data for 484 patients. Patient age ranged from 2 to 20 years (mean ± SD, 12.5 ± 3.9) and 340 (68%) were males. Overall, patient BMI ranged from 7 to 50 (22.7 ± 6.1). Obesity (BMI 18-50, mean 29.1) was present in 140 children aged 2-19.6 (11.3 ± 4.1). The overall mean IVST was 20.5 ± 9.6 mm and the overall mean PWT was 11.0 ± 8.4 mm. The mean IVST in the obese patients was 21.6 ± 10.0 mm and mean PWT was 13.3 ± 14.7 mm. The mean IVST in the non-obese patients was 20.1 ± 9.5 mm and mean PWT was 10.4 ± 4.3 mm. Obesity was not significantly associated with IVST (p = 0.12), but was associated with increased PWT (0.0011). Obesity is associated with increased PWT but not IVST in children with HCM. Whether obesity and its impact on LVH influences clinical outcomes in children with HCM needs to be studied.

Little is known about lone atrial fibrillation (AF) in pediatrics and its risk factors due to low prevalence. We sought to determine risk factors and estimate recurrence rates in children with lone AF using a large clinical database. Using the Explorys clinical database, we retrospectively identified patients who were below 20 years of age at the time of their AF diagnosis. Patients with congenital heart disease, cardiomyopathy, prior open heart surgery, or thyroid disease were excluded. Out of 7,969,230 children identified, 1910 had AF and 1570 met the definition of lone AF. The prevalence of lone AF was 7.5 per 100,000 children. In comparison to young children (0-4 years), risk for lone AF increased with age (adjusted odds ratio (aOR) 1.2 [95% CI 0.9-1.5, P = 0.21] in those 5-9 years, aOR 1.7 [95% CI 1.3-2.1, P < 0.001] in those 10-14 years, and aOR 10.7 [95% CI 8.7-13.2, P < 0.001] in those 15-19 years). Risk of lone AF was also higher in males than females (aOR 1.7 [95% CI 1.5-1.9, P < 0.001]), and was higher in obese children (BMI ≥ 95th percentile) versus children with normal BMI (aOR 1.3 [95% CI 1.1-1.5], P < 0.001), but there was no difference between overweight (BMI = 85th-94th percentile) and normal (P = 0.14). One-month recurrence rate was 15%, and increased with age. In this large pediatric cohort, the prevalence of lone AF was low, but risk was higher in males and increased with age and obesity. Older children with lone AF had higher rates of recurrence.

Transient complete heart block (TCHB) is defined as complete interruption of atrioventricular conduction (AVC) after cardiac surgery followed by return of conduction. This study aimed to assess the risk for the development of late complete heart block (LCHB) after recovery of TCHB and to examine the electrocardiographic and electrophysiologic properties of the AVC system after TCHB. Of the 44 patients in this study who experienced TCHB, 37 recovered completely. Seven patients progressed from TCHB to intermittent CHB or LCHB requiring pacemaker implantation. Preoperative, early postoperative, and late postoperative electrocardiograms as well as postoperative atrial stimulation were obtained. The results showed that the median duration of TCHB was 5 days in the TCHB group compared with 9 days in the LCHB group (p = 0.01). All 37 subjects with TCHB recovered AVC within 12 days, but only two with LCHB did so (p = 0.02). The risk of LCHB for the patients with 7 days of postoperative TCHB or longer was 13 times greater than for the patients with fewer than 7 days of TCHB (p = 0.01). The median late postoperative PR interval was slightly but significantly longer in the LCHB group than in the TCHB group (p = 0.02). In contrast, the electrophysiologic properties between the two groups did not differ significantly. From those findings, we concluded that delayed recovery of AVC after surgical TCHB (≥7 days), but not electrophysiologic properties of recovered AVC assessed early in the postoperative period strongly, predicts risk of LCHB. Follow-up evaluation of AVC is particularly indicated for the delayed recovery group.