Enormous Pulmonary Arteries and a Late Diagnosis of a Common Congenital Cardiac Issue: A Case Report

Background: Noonan’s syndrome is the second most common congenital cardiac syndrome after Down syndrome. Classically it is associated with pulmonary stenosis, Hypertrophic Cardiomyopathy (HCM), and Atrial Septal Defects (ASD). Late presentations, milder phenotypes and atypical presentations can occur in adult life and have cardiovascular implications. Case Summary: A 62-year-old presented to the emergency department with chest pain and atrial fibrillation with fast ventricular rate and RBBB morphology. A transthoracic echocardiogram demonstrated a massive Pulmonary Artery (PA), concerning for pulmonary hypertension and an atrial septal defect (ASD). Right heart catheterization indicated enormous coronary artery ectasia but normal PA pressures and wedge pressures. He was identified as a late presentation of Noonan’s syndrome on subsequent genetic testing. Discussion: Some series indicate a prevalence of 1 in 100 for mild Noonan’s syndrome phenotypes, highlighting the importance of understanding its cardiac presentations. In this case, we present a man with minimal symptoms but gross pathologies of his pulmonary and coronary arteries. Furthermore, pulmonary artery dilatation without pulmonary valve pathology has not been reported in the literature, and only a few reports of coronary artery ectasia are reported.