Background: Understanding the clinical course and short-term outcomes of suspected myocarditis following COVID-19 vaccination has important public health implications in the decision to vaccinate youth. Methods: We retrospectively collected data on patients <21 years-old presenting before 7/4/2021 with suspected myocarditis within 30 days of COVID-19 vaccination. Lake Louise criteria were used for cardiac magnetic resonance imaging (cMRI) findings. Myocarditis cases were classified as confirmed or probable based on the Centers for Disease Control and Prevention definitions. Results: We report on 139 adolescents and young adults with 140 episodes of suspected myocarditis (49 confirmed, 91 probable) at 26 centers. Most patients were male (N=126, 90.6%) and White (N=92, 66.2%); 29 (20.9%) were Hispanic; and median age was 15.8 years (range 12.1-20.3, IQR 14.5-17.0). Suspected myocarditis occurred in 136 patients (97.8%) following mRNA vaccine, with 131 (94.2%) following the Pfizer-BioNTech vaccine; 128 (91.4%) occurred after the 2nd dose. Symptoms started a median of 2 days (range 0-22, IQR 1-3) after vaccination. The most common symptom was chest pain (99.3%). Patients were treated with nonsteroidal anti-inflammatory drugs (81.3%), intravenous immunoglobulin (21.6%), glucocorticoids (21.6%), colchicine (7.9%) or no anti-inflammatory therapies (8.6%). Twenty-six patients (18.7%) were in the ICU, two were treated with inotropic/vasoactive support, and none required ECMO or died. Median hospital stay was 2 days (range 0-10, IQR 2-3). All patients had elevated troponin I (N=111, 8.12 ng/mL, IQR 3.50-15.90) or T (N=28, 0.61 ng/mL, IQR 0.25-1.30); 69.8% had abnormal electrocardiograms and/or arrythmias (7 with non-sustained ventricular tachycardia); and 18.7% had left ventricular ejection fraction (LVEF) <55% on echocardiogram. Of 97 patients who underwent cMRI at median 5 days (range 0-88, IQR 3-17) from symptom onset, 75 (77.3%) had abnormal findings: 74 (76.3%) had late gadolinium enhancement, 54 (55.7%) had myocardial edema, and 49 (50.5%) met Lake Louise criteria. Among 26 patients with LVEF <55% on echocardiogram, all with follow-up had normalized function (N=25). Conclusions:Most cases of suspected COVID-19 vaccine myocarditis occurring in persons <21 years have a mild clinical course with rapid resolution of symptoms. Abnormal findings on cMRI were frequent. Future studies should evaluate risk factors, mechanisms, and long-term outcomes.

Failure to thrive is common in infants with hypoplastic left heart syndrome and its variants and those with poor growth may be at risk for worse surgical and neurodevelopmental outcomes. The etiology of growth failure in this population is multifactorial and complex, but may be impacted by nutritional intervention. There are no consensus guidelines outlining best practices for nutritional monitoring and intervention in this group of infants. The Feeding Work Group of the National Pediatric Cardiology Quality Improvement Collaborative performed a literature review and assessment of best nutrition practices from centers participating in the collaborative in order to provide nutritional recommendations and levels of evidence for those caring for infants with single ventricle physiology.

Objectives To describe growth patterns in infants with single ventricle physiology and determine factors influencing growth. Study design Data from 230 subjects enrolled in the Pediatric Heart Network Infant Single Ventricle Enalapril Trial were used to assess factors influencing change in weight-for-age z-score (Δz) from study enrollment (0.7 ± 0.4 months) to pre-superior cavopulmonary connection (SCPC) (5.1 ± 1.8 months, period 1), and pre-SCPC to final study visit (14.1 ± 0.9 months, period 2). Predictor variables included patient characteristics, feeding regimen, clinical center, and medical factors during neonatal (period 1) and SCPC hospitalizations (period 2). Univariate regression analysis was performed, followed by backward stepwise regression and bootstrapping reliability to inform a final multivariable model. Results Weights were available for 197/230 subjects for period 1 and 173/197 for period 2. For period 1, greater gestational age, younger age at study enrollment, tube feeding at neonatal discharge, and clinical center were associated with a greater negative Δz (poorer growth) in multivariable modeling (adjusted R2 = 0.39, p < 0.001). For period 2, younger age at SCPC and greater daily caloric intake were associated with greater positive Δz (better growth) (R2 = 0.10, p = 0.002). Conclusions Aggressive nutritional support and earlier SCPC are modifiable factors associated with a favorable change in weight-for-age z-score.

Objectives The Single Ventricle Reconstruction trial randomized 555 subjects with a single right ventricle undergoing the Norwood procedure at 15 North American centers to receive either a modified Blalock-Taussig shunt or right ventricle-to-pulmonary artery shunt. Results demonstrated a rate of death or cardiac transplantation by 12 months postrandomization of 36% for the modified Blalock-Taussig shunt and 26% for the right ventricle-to-pulmonary artery shunt, consistent with other publications. Despite this high mortality rate, little is known about the circumstances surrounding these deaths. Methods There were 164 deaths within 12 months postrandomization. A committee adjudicated all deaths for cause and recorded the timing, location, and other factors for each event. Results The most common cause of death was cardiovascular (42%), followed by unknown cause (24%) and multisystem organ failure (7%). The median age at death for subjects dying during the 12 months was 1.6 months (interquartile range, 0.6 to 3.7 months), with the highest number of deaths occurring during hospitalization related to the Norwood procedure. The most common location of death was at a Single Ventricle Reconstruction trial hospital (74%), followed by home (13%). There were 29 sudden, unexpected deaths (18%), although in retrospect, 12 were preceded by a prodrome. Conclusions In infants with a single right ventricle undergoing staged repair, the majority of deaths within 12 months of the procedure are due to cardiovascular causes, occur in a hospital, and within the first few months of life. Increased understanding of the circumstances surrounding the deaths of these single ventricle patients may reduce the high mortality rate. (J Thorac Cardiovasc Surg 2012;144:907-14)