Atrial Myxoma in a Patient with Hypertrophic Cardiomyopathy

Abstract

Atrial myxoma is the most common primary cardiac tumor. Patients with atrial myxoma typically present with obstructive, embolic, or systemic symptoms; asymptomatic presentation is very rare. To our knowledge, isolated association of atrial myxoma with hypertrophic cardiomyopathy has been reported only once in the English-language medical literature. We report the case of an asymptomatic 71-year-old woman with known hypertrophic cardiomyopathy in whom a left atrial mass was incidentally identified on cardiac magnetic resonance images. After surgical excision of the mass and partial excision of the left atrial septum, histopathologic analysis confirmed the diagnosis of atrial myxoma. The patient was placed on preventive implantable cardioverter-defibrillator therapy and remained asymptomatic. The management of asymptomatic cardiac myxoma is a topic of debate, because no reports definitively favor either conservative or surgical measures.

Primary cardiac tumors are rare entities, with a prevalence on autopsy of less than 1%.¹ Approximately three quarters of primary heart tumors are benign, and approximately 75% of those are myxomas. The remainder are lipomas, papillary fibroelastomas, and rhabdomyomas.² Cardiac myxomas usually develop in the atria—the vast majority in the left atrium, specifically from the interatrial septum at the border of the fossa ovalis.³ Patients with atrial myxoma typically present with cardiovascular symptoms such as heart failure and pulmonary hypertension, secondary to mitral valve obstruction. They can also present with neurologic deficits, transient or permanent visual loss, or involvement of internal viscera secondary to embolic phenomena. Constitutional symptoms include fatigue, fever, erythematous rash, arthralgia, myalgia, and weight loss.³ An asymptomatic presentation is extremely rare. Hypertrophic cardiomyopathy (HCM) is often diagnosed incidentally, and it can also present with obstructive symptoms similar to those of myxoma.⁴ We describe and discuss the case of an asymptomatic elderly patient with known HCM and an incidentally diagnosed atrial myxoma.

Case Report

In July 2010, a 71-year-old woman was referred for echocardiographic screening after her daughter had been diagnosed with HCM. The woman was asymptomatic, and her medical history was unremarkable except for well-controlled hypertension and hyperlipidemia. Physical examination yielded only a grade 1/6, early-peaking, short systolic murmur, faintly heard at the upper left sternal border.

A transthoracic echocardiogram showed asymmetric hypertrophy of the basal and mid-anteroseptal wall, consistent with HCM. Cardiac magnetic resonance images showed asymmetric left ventricular hypertrophy with a thickened interventricular septum (Fig. 1A) and a 1.7-cm mass in the left atrium along the interatrial septum (Fig. 1B). Transesophageal echocardiograms showed a 1.2 × 2.2-cm, broad-based, irregular mass in the left atrium, arising from the interatrial septum near the foramen ovale and protruding into the left atrial lumen (Figs. 2 and 3).

Fig. 1 Cardiac magnetic resonance T2-weighted, fat-saturated images. A) Short-axis view shows asymmetric left ventricular hypertrophy and a thickened interventricular septum (maximal thickness, 2.7 cm) with no evident outflow tract obstruction. B) Long-axis view shows a hyperintense 1.7-cm lesion in the left atrium along the interatrial septum. The increased signal intensity on T2 weighting is consistent with myxoma.

Fig. 2 Transesophageal echocardiogram shows an irregular, hyperechoic, broad-based mass arising from the interatrial septum and protruding into a moderately enlarged left atrium. Despite the atypical appearance of the mass, its location suggests atrial myxoma.

Fig. 3 Three-dimensional transesophageal echocardiogram (long-axis view of longitudinal cut through the left atrium) shows the mass protruding into the lumen of the left atrium.

AV = aortic valve; LAA = left atrial appendage; TV = tricuspid valve

The patient underwent complete surgical excision of the left atrial mass and partial excision of the left atrial septum (Fig. 4A). Histopathologic analysis of the excised mass confirmed the diagnosis of atrial myxoma (Fig. 4B). Because of the subsequent sudden cardiac death of her younger sister, the patient was placed on preventive implantable cardioverter-defibrillator therapy. She remained asymptomatic.

Fig. 4 A) Photograph shows the excised mass. B) Photomicrograph shows features of cardiac myxoma: minimal cellularity, only scattered spindle cells, and scant pink cytoplasm in a loose myxoid stroma (H & E, orig. ×10).

Discussion

To our knowledge, the association of atrial myxoma with HCM has been reported only once in the English-language medical literature,⁵ in a 67-year-old man who presented with exertional dyspnea. Left atrial myxomas and HCM have been independently described in patients who have progressive cardiomyopathic lentiginosis (LEOPARD syndrome), a rare autosomal dominant disease with complex features that involve the skin, skeletal structure, and cardiovascular system.⁶ Our patient had no features of lentiginosis. Moreover, she did not report that any direct relatives exhibited spotty pigmentation or had a myxoma. Her case is most likely an example of 2 relatively rare and unrelated conditions. This association is so rare that its pathophysiologic relevance, clinical course, and management have not been defined.

The management of asymptomatic cardiac myxomas remains a topic of debate, because no reports clearly favor either conservative or surgical measures. As with the previously described patient,⁵ our patient underwent tumor excision. The decision to proceed surgically was made because of her underlying and familial HCM, which increased her risk of complications.^7,8