Association of Noonan Syndrome, Noncompaction of the Myocardium, Hypertrophic Cardiomyopathy, and Long QT Syndrome: A Case Series

Background: The Noonan syndrome (NS) is a rare genetic disorder characterized by manifestations such as short stature, a webbed neck, micrognathia, and hypertelorism.Although NS predisposes to cardiac disorders such as hypertrophic cardiomyopathy (HCM), it has only rarely been associated with noncompaction cardiomyopathy (NCCM), an embryonic anomaly defined by excessive trabeculation and formation of deep myocardial recesses.The clinical presentation of NCCM ranges from asymptomatic to severe thromboembolic events.This study aims to describe cardiovascular changes and outcomes in patients with NS and NCCM followed at the cardiology department of a Brazilian hospital.Methods: Observational, longitudinal, prospective follow-up of three adult patients with the NS phenotype.All underwent echocardiography and cardiac magnetic resonance imaging (CMR).Data such as age, sex, family history, symptom onset, and outcomes of interest, such as thromboembolic events, heart transplantation (HTx), and death, were analyzed.Results: All three patients followed (one male-female sibling pair and one unrelated male) had NCCM with ventricular dysfunction.The female patient also had the long QT syndrome (LQTS).All developed apical thrombi, in the left ventricle in two cases.The female patient underwent successful HTx, while the two males died after decompensation of heart failure (HF) progressing to cardiogenic shock.Conclusion: This case series highlights the need for early diagnosis and family screening of patients with NS to optimize treatment and improve prognosis.There is no prior record in the literature of the association of all conditions described herein in the same patient.