Perez, Yalile

Introduction: Long QT syndrome (LQTS) is an autosomal dominant disorder characterized by a prolonged QT interval on a 12-lead electrocardiogram (ECG). Cascade genetic testing for LQTS is standard of care, including in infants, but takes 2-4 weeks for return of results. For newborns of parent with confirmed LQTS, the ECG is obtained after birth as an initial assessment, but QTc values during the immediate newborn period may be misleading. Thus, our objective was to determine the ECG’s diagnostic accuracy in the first 48 hours of life for neonates born to a parent with LQTS. Methods: We performed a retrospective review of the electronic medical records of neonates born to a parent with ≥ 1 pathogenic variant in a LQTS-causative gene for which at least 1 ECG in the first 48 hours of life was obtained. Clinical data was collected on all neonates with focus on the 12-lead ECG, family history, and genetic testing results. The sensitivity and specificity of the diagnostic ECG were calculated using QTc thresholds of 440, 460, and 470 ms. Results: Overall, 70 infants (35 [50%] females) met inclusion criteria and the mean QTc on the first ECG was 484 ± 61 ms. Following genetic testing, a LQTS-causing variant was identified in 46 infants (66%), including 22 (48%) with LQT1 ( KCNQ1 ), 12 (26%) with LQT2 ( KCNH2 ), and 8 (17%) with LQT3 ( SCN5A ). Mean QTc in the first 48 hours of life for neonates that ultimately were genotype-positive was 502 ± 59 ms compared to 451 ± 50 ms (p < 0.001) for genotype-negative neonates. When using a recommended threshold QTc of ≥ 440 ms, 6/46 genotype-positive neonates (13%) were missed (underdiagnosed) and 13/24 genotype-negative neonates (54%) were overdiagnosed (sensitivity: 87%, specificity: 45%). At a QTc threshold ≥ 460 ms, 15 (21%) were classified erroneously (sensitivity: 85%, specificity: 67%) while at a threshold of ≥ 470 ms, 18 (26%) were misclassified (sensitivity: 76%, specificity: 71%). Conclusions: Although a baseline ECG should still be obtained before a newborn’s dismissal, reliance solely on the QTc for diagnosing LQTS and initiating therapy will result in an unacceptable number of misclassifications. Thus, genetic testing must be initiated prior to the baby’s discharge and proper anticipatory guidance is vital while awaiting genetic test results.

Aortic dissection is often a fatal condition if not recognized and treated emergently. Fortunately, it is extremely rare in children and adolescents. We report a case of an adolescent boy who survived an aortic dissection due to severe aortic root dilation. A comprehensive history and physical examination, including family history, can facilitate an early diagnosis of connective tissue diseases, such as Loeys-Dietz syndrome (LDS).

Abstract Background Myocarditis following coronavirus disease 2019 (COVID-19) mRNA vaccines (Pfizer-BioNTech and Moderna) has been increasingly reported. Incidence rates in the general population are lacking, with pericarditis rather than myocarditis diagnostic codes being used to estimate background rates. This comparison is critical for balancing the risk of vaccination with the risk of no vaccination. Methods A retrospective case series was performed using the Mayo Clinic COVID-19 Vaccine Registry. We measured the incidence rate ratio (IRR) for myocarditis temporally related to COVID-19 mRNA vaccination compared with myocarditis in a comparable population from 2016 through 2020. Clinical characteristics and outcomes of the affected patients were collected. A total of 21 individuals were identified, but ultimately 7 patients met the inclusion criteria for vaccine-associated myocarditis. Results The overall IRR of COVID-19–related myocarditis was 4.18 (95% confidence interval [CI], 1.63–8.98), which was entirely attributable to an increased IRR among adult males (IRR, 6.69; 95% CI, 2.35–15.52) compared with females (IRR 1.41; 95% CI, .03–8.45). All cases occurred within 2 weeks of a dose of the COVID-19 mRNA vaccine, with the majority occurring within 3 days (range, 1–13) following the second dose (6 of 7 patients, 86%). Overall, cases were mild, and all patients survived. Conclusions Myocarditis is a rare adverse event associated with COVID-19 mRNA vaccines. It occurs in adult males with significantly higher incidence than in the background population. Recurrence of myocarditis after a subsequent mRNA vaccine dose is not known at this time.