Supraventricular Tachycardia Associated with Cardiac Hemangioma on the Anterior Mitral Valve Leaflet: A Case Report

Background: Cardiac hemangiomas are exceedingly rare benign vascular tumors, representing <2% of primary cardiac tumors. Case Presentation: A 65-year-old female patient with a history of palpitations, hypothyroidism, and hypoparathyroidism presented with an acute onset of palpitations and dyspnea. On physical examination, the patient had regular tachycardia with clear and equal bilateral air entry. Initial laboratory tests and chest X-ray showed no acute abnormalities. An electrocardiogram (ECG) showed narrow-complex supraventricular tachycardia (SVT) with a heart rate of 170 bpm and a QRS duration of 80 ms, consistent with atrioventricular nodal reentrant tachycardia (AVNRT), which was unresponsive to vagal maneuvers but was successfully converted with 6 mg of intravenous adenosine. Multimodality imaging, including transthoracic echocardiography (TTE), transesophageal echocardiography (TEE), and cardiac magnetic resonance imaging (CMR), was performed. TTE showed a fixed, normoechoic mass (1-1.2 cm) at the aortomitral junction involving the A2 segment of the anterior mitral leaflet; TEE described a nonobstructive heterogeneous echodensity (17 × 6 mm) at the leaflet base near the intervalvular fibrosa; CMR showed a 13 × 11 mm arched structure on the anterior mitral leaflet, beneath the aortic valve, with cavity-like perfusion, T2 hyperintensity, and late gadolinium enhancement. Surgical resection was performed 3 weeks after the diagnosis, and histopathology showed a remodeled remnant hemangioma. Postoperatively, continuous telemetry and long-term clinical and serial ECG follow-up confirmed complete resolution of the arrhythmia without tumor recurrence. Conclusion: We report a cardiac hemangioma on the left atrial side of the anterior mitral leaflet, extending slightly into the left atrial cavity without obstructing blood flow, in a patient with episodes of supraventricular tachycardia. She recovered well after tumor resection, with no clinical signs of arrhythmia recurrence.