Multisystem inflammatory syndrome in children (MIS-C) and "Near MIS-C": A continuum?

Introduction: Reports of multisystem inflammatory syndrome in children (MIS-C), following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, have been increasing worldwide, with an incidence varying significantly across studies based on the definition used for the diagnosis. At our tertiary medical center in Lebanon, we encountered several cases that presented a diagnostic challenge because they mimicked MIS-C but did not meet the US Centers for Disease Control and Prevention (CDC) definition. We decided to review these cases and describe their features in comparison with cases that met the CDC criteria of MIS-C and those that had an alternative diagnosis. Methods: This is a retrospective chart review of subjects aged <19 years old admitted to the American University of Beirut Medical Center (AUBMC) between March 1, 2020, and May 31, 2021, with suspected or confirmed MIS-C, following documented COVID-19 infection, with sufficient or insufficient criteria for diagnosis. Subjects were classified into 3 groups: "MIS-C", "Near MIS-C" and "Alternative Diagnosis". Results: A total number of 29 subjects were included in our cohort. Fever was present in all subjects. In the MIS-C group, evidence for cardiovascular system involvement was the most common feature followed by the mucocutaneous and gastrointestinal systems. In the "Near MIS-C" and "Alternative Diagnosis" group, gastrointestinal symptoms were the most common with only one patient with cardiac abnormalities and none with coagulopathy. Subjects with typical MIS-C presentation had higher inflammatory markers when compared to subjects in the other groups. Almost all the subjects had positive IgG for SARS-CoV-2. Of the 29 subjects, the Royal College of Paediatrics and Child Health (RCPCH) case definition would have identified all suspected cases without an alternative diagnosis as MIS-C, whereas the World Health Organization (WHO) and the CDC definitions would have excluded 6 and 10 subjects, respectively. Conclusion: MIS-C presents a diagnostic challenge due to the nonspecific symptoms, lack of pathognomonic findings, and potentially fatal complications. More research is needed to fully understand its pathogenesis, clinical presentation spectrum, and diagnostic criteria. Based on our experience, we favor the hypothesis that MIS-C has a continuum of severity that necessitates revisiting and unifying the current definitions.

Balloon Valvuloplasty for Congenital Aortic Stenosis: Experience at a Tertiary Center in a Developing Country.

BACKGROUND: Aortic valve stenosis accounts for 3-6% of congenital heart disease. Balloon aortic valvuloplasty (BAV) is the preferred therapeutic intervention in many centers. However, most of the reported data are from developed countries. MATERIALS AND METHODS: We performed a retrospective single-center study involving consecutive eligible neonates and infants with congenital aortic stenosis admitted for percutaneous BAV between January 2005 and January 2016 to our tertiary center. We evaluated the short- and mid-term outcomes associated with the use of BAV as a treatment for congenital aortic stenosis (CAS) at a tertiary center in a developing country. Similarly, we compared these outcomes to those reported in developed countries. RESULTS: During the study period, a total of thirty patients, newborns (n = 15) and infants/children (n = 15), underwent BAV. Left ventricular systolic dysfunction was present in 56% of the patients. Isolated AS was present in 19 patients (63%). Associated anomalies were present in 11 patients (37%): seven (21%) had coarctation of the aorta, two (6%) had restrictive ventricular septal defects, one had mild Ebstein anomaly, one had Shone's syndrome, and one had cleft mitral valve. BAV was not associated with perioperative or immediate postoperative mortality. Immediately following the valvuloplasty, a more than mild aortic regurgitation was noted only in two patients (7%). A none-to-mild aortic regurgitation was noted in the remaining 93%. One patient died three months after the procedure. At a mean follow-up of 7 years, twenty patients (69%) had more than mild aortic regurgitation, and four patients (13%) required surgical intervention. Kaplan-Meier freedom from aortic valve reintervention was 97% at 1 year and 87% at 10 years of follow-up. CONCLUSION: Based on outcomes encountered at a tertiary center in a developing country, BAV is an effective and safe modality associated with low complication rates comparable to those reported in developed countries.

Founder Mutation in N Terminus of Cardiac Troponin I Causes Malignant Hypertrophic Cardiomyopathy.

BACKGROUND: Cardiac troponin I (TNNI3) gene mutations account for 3% of hypertrophic cardiomyopathy and carriers have a heterogeneous phenotype, with increased risk of sudden cardiac death (SCD). Only one mutation (p.Arg21Cys) has been reported in the N terminus of the protein. In model organisms, it impairs PKA (protein kinase A) phosphorylation, increases calcium sensitivity, and causes diastolic dysfunction. The phenotype of this unique mutation in patients with hypertrophic cardiomyopathy remains unknown. METHODS: We sequenced 29 families with hypertrophic cardiomyopathy enriched for pediatric-onset disease and identified 5 families with the TNNI3 p.Arg21Cys mutation. Using cascade screening, we studied the clinical phenotype of 57 individuals from the 5 families with TNNI3 p.Arg21Cys-related cardiomyopathy. We performed survival analysis investigating the age at first SCD in carriers of the mutation. RESULTS: All 5 families with TNNI3 p.Arg21Cys were from South Lebanon. TNNI3 p.Arg21Cys-related cardiomyopathy manifested a malignant phenotype-SCD occurred in 30 (53%) of 57 affected individuals at a median age of 22.5 years. In select carriers without left ventricular hypertrophy on echocardiogram, SCD occurred, myocyte disarray was found on autopsy heart, and tissue Doppler and cardiac magnetic resonance imaging identified subclinical disease features such as diastolic dysfunction and late gadolinium enhancement. CONCLUSIONS: The TNNI3 p.Arg21Cys mutation has a founder effect in South Lebanon and causes malignant hypertrophic cardiomyopathy with early SCD even in the absence of hypertrophy. Genetic diagnosis with this mutation may be sufficient for risk stratification for SCD.

Premature Valvular Heart Disease in Homozygous Familial Hypercholesterolemia.

Valvular heart disease frequently occurs as a consequence of premature atherosclerosis in individuals with familial hypercholesterolemia (FH). Studies have primarily focused on aortic valve calcification in heterozygous FH, but there is paucity of data on the incidence of valvular disease in homozygous FH. We performed echocardiographic studies in 33 relatively young patients (mean age: 26 years) with homozygous FH (mean LDL of 447 mg/dL, 73% on LDL apheresis) to look for subclinical valvulopathy. Twenty-one patients had evidence of valvulopathy of the aortic or mitral valves, while seven subjects showed notable mitral regurgitation. Older patients were more likely to have aortic valve calcification (>21 versus ≤21 years: 59% versus 12.5%; p = 0.01) despite lower LDL levels at the time of the study (385 versus 513 mg/dL; p = 0.016). Patients with valvulopathy were older and had comparable LDL levels and a lower carotid intima-media thickness. Our data suggests that, in homozygous FH patients, valvulopathy (1) is present across a wide age spectrum and LDL levels and (2) is less likely to be influenced by lipid-lowering treatment. Echocardiographic studies that focused on aortic root thickening and stenosis and regurgitation are thus likely an effective modality for serial follow-up of subclinical valvular heart disease.

Low-density lipoprotein levels and not mutation status predict intima-media thickness in familial hypercholesterolemia.

BACKGROUND: Intima-media thickness (IMT) is a well-described marker of cardiovascular disease. In this study we aim to determine whether low-density lipoprotein (LDL) levels and disease-related mutation status can predict IMT in patients with severe familial hypercholesterolemia (FH) referred for or on LDL apheresis. METHODS: Genetic screening, lipid profile testing, and IMT measurements were performed on a series of 33 severe FH patients (19 homozygous) on LDL apheresis treatments (LDL 447 ± 151 mg/dL, age range 6-60 years). Data were then compared with literature IMT-LDL data for normal subjects, mild FH patients, and severe FH patients (18, 41, and 6 studies, respectively). RESULTS: Age-adjusted IMT was linearly related to LDL levels over a wide range of values (<500 mg/dL), except for the severe FH no-apheresis cohort. Alternatively, our severe FH population (mostly on apheresis) did follow the mild FH/control age-adjusted IMT-LDL relation. CONCLUSIONS: In severe FH, measuring LDL levels is more predictive of increased IMT than genetic screening.

Rupture of sinus of Valsalva aneurysm with aorto-biventricular fistulas and right-ventricular outflow tract obstruction: a unique association.

Sinus of Valsalva aneurysms are a rare entity. Rupture of such aneurysms is a major cause of aortocardiac fistulas usually occurring between the right sinus of Valsalva and right cardiac chambers. We report an exceptional case of a ruptured congenital sinus of Valsalva aneurysm with fistulas involving both the right- and left-ventricular outflow tracts and causing RVOT obstruction. We also demonstrate the utility of computed tomography angiography and transesophageal echocardiography in diagnosing these fistulas.

Homozygous familial hypercholesterolemia in Lebanon: a genotype/phenotype correlation.

Familial hypercholesterolemia (FH) is an inherited disease characterized by the deposition of LDL in tissues causing premature atherosclerosis. Many genes are implicated in FH resulting in a large variability in the phenotype. DNA sequencing of the LDLR gene was done for forty patients clinically diagnosed with homozygous FH and forty family members variably affected. Patients underwent noninvasive heart and vascular studies. Statistical and pedigree analyses were used to correlate the different genotypes with the phenotypes. The prevalence of homozygosity at the Lebanese allele (2043C>A) is 45%. However, 27.5% of the patients have no mutations at all in the LDLR gene, and 27.5% are either heterozygous for the 2043C>A mutation, heterozygous for a mutation in another exon of the LDLR gene, or combined heterozygous for two different mutations. We confirm previous reports on the higher prevalence of FH in Lebanon. Our results do, however contradict previous reports on an assumed higher prevalence among the Christian Lebanese. Mutations in the LDLR especially combined heterozygosity can cause a severe phenotype similar to the homozygous mutation in the Lebanese allele. This information is particularly important in targeting the more prevalent heterozygotes in the general population with early diagnosis and intervention.

Pulmonary hypertension in children and young adults with sickle cell disease: evidence for familial clustering.

BACKGROUND: Pulmonary hypertension (PHTN) is increasingly recognized as a serious complication of sickle cell disease (SCD). Our objective was to determine the prevalence of PHTN and identify factors associated with PHTN among children and young adults with SCD in Lebanon. PROCEDURE: From June 2004 to June 2008, 90 patients were studied. Correlation of TRV with LDH, mean corpuscular volume (MCV), fetal hemoglobin (HbF), hydroxyurea use, and G6PD deficiency was performed. Transthoracic Doppler echocardiography was performed during steady-state at each patient's initial visit and yearly thereafter. PHT was defined as a tricuspid regurgitant jet velocity (TRV) > or =2.5 m/sec. RESULTS: Twenty-seven patients (31.8%) were found to have PHTN. They had significantly higher LDH levels (P = 0.008) and MCV (P = 0.024). There was a higher percentage of patients on hydroxyurea in the group with PHTN (78% vs. 50%, P = 0.015). Furthermore, five children, mean age 9.8 years (range, 6-13 years), with initially normal TRV developed PHTN while on hydroxyurea for at least 3 years, at a mean dose of 19.2 mg/kg/day (range, 14-24). PHTN clustered in families and was found in all members with SCD in 7 of the 21 families studied; they contributed 16 of the 27 patients with PHTN. None of the 21 patients with PHTN were G6PD deficient compared to 4 of 36 without PHTN. CONCLUSIONS: PHTN was common, associated with increased hemolysis but not G6PD deficiency, and clustered in families. Moreover, PHTN developed despite hydroxyurea therapy in five patients.