Late Diagnosis of Noonan Syndrome Presenting With Infective Endocarditis: A Multidisciplinary Challenge in an Underserved Population.

BACKGROUND Noonan syndrome is a clinically diagnosed genetic disorder frequently associated with congenital and structural cardiac abnormalities such as valvular dysplasia and cardiomyopathy, which may predispose patients to infective endocarditis. Delayed recognition, particularly in underserved populations, can lead to advanced cardiac complications and complex presentations. CASE REPORT A 29-year-old woman from a rural area with no previous medical history presented with severe respiratory distress, weight loss, and newly detected cardiac murmurs. Physical examination revealed dysmorphic features suggestive of Noonan syndrome, including low-set ears, hypertelorism, short stature, and broad thorax, leading to a clinical diagnosis. Echocardiography demonstrated severe mitral regurgitation with mobile vegetations, a pedunculated mass in the right ventricular outflow tract, left atrial enlargement, reduced right ventricular systolic function (Tricuspid Annular Plane Systolic Excursion, 14 mm), and mild pericardial effusion. Blood cultures remained negative after prolonged incubation, consistent with blood culture-negative infective endocarditis. Concomitant hyperthyroidism contributed to heart failure decompensation. A multidisciplinary team initiated empirical antibiotics, heart failure therapy, thyroid control, and supportive care. The patient improved clinically and was discharged with a plan for elective valve surgery after infection control. CONCLUSIONS This case highlights infective endocarditis as a serious complication in late-diagnosed Noonan syndrome due to underlying structural cardiac abnormalities. Early recognition of Noonan syndrome and multidisciplinary management are essential to improve outcomes and ensure timely referral for definitive cardiac intervention.