Noonan Syndrome With Multiple Lentigines Mimicking Obstructive Hypertrophic Cardiomyopathy Treated by Septal Myectomy

Noonan syndrome with multiple lentigines (NSML) is a rare RASopathy characterized by lentigines, craniofacial anomalies, and cardiac involvement. Hypertrophic cardiomyopathy (HCM) with left ventricular outflow tract obstruction is a frequent phenotype and may require interventional therapy.

We present a 43-year-old woman with NSML and obstructive HCM. Despite optimized pharmacologic therapy and implantable cardioverter-defibrillator implantation, she developed progressive dyspnea and palpitations. Multidisciplinary heart team evaluation favored surgical septal myectomy with papillary muscle plasty, given unfavorable anatomy for alcohol septal ablation. Postoperative echocardiography showed marked gradient reduction and symptom relief.

Approximately 5% to 10% of patients with HCM remain refractory to medical therapy. In phenocopies such as NSML, therapeutic decisions should be individualized. Surgical myectomy is a safe alternative when septal anatomy precludes alcohol septal ablation.

Septal reduction therapies may be considered in NSML with left ventricular outflow tract obstruction. Heart team discussion is essential. Surgical myectomy can provide sustained functional improvement.