Atrial Myxoma and Other Cardiac Tumors¶

Chapter 282 | Part 6: Disorders of the Cardiovascular System

KEY CLINICAL POINTS¶

Atrial myxoma is the most common primary cardiac tumor, accounting for 1/3–1/2 of all cases at postmortem examination.
Imaging modalities (TTE, TEE, MRI, CT) are critical for diagnosis, with MRI offering superior tissue characterization and differentiation from thrombus.
Myxomas often present with obstructive symptoms (mitral valve obstruction), embolic phenomena, or constitutional symptoms due to cytokine release.
Surgical excision is the definitive treatment for myxomas and most benign tumors, with early intervention critical to prevent complications.
Familial myxomas (Carney complex) are associated with PRKAR1A gene mutations and may involve multiple organ systems.

1. DEFINITION & OVERVIEW¶

Cardiac tumors are broadly classified into primary (originating in the heart) and secondary (metastatic). Primary tumors include benign (e.g., myxomas, lipomas) and malignant (e.g., sarcomas) types. Atrial myxoma is the most common primary cardiac tumor in adults, while rhabdomyomas are common in infants. Secondary tumors are more common in patients with end-stage metastatic cancer.

Table 282-1: Imaging Modalities and Their Utility in the Evaluation of Cardiac Tumors¶

MODALITY	UTILITY IN CARDIAC TUMOR EVALUATION
Transthoracic echocardiography (TTE) (including 2D, 3D, and contrast)	Assessment of tumor location, size, and impact on adjacent structures (e.g., valves, pericandium)
Transesophageal echocardiography (TEE)	Improved tumor characterization and spatial resolution; aids in surgical planning
Cardiac magnetic resonance imaging (MRI) with gadolinium contrast	Tissue characterization, tumor size, and differentiation from thrombus
Gated cardiac CT	Anatomic assessment, calcified lesion evaluation, and extracardiac tumor involvement
Nuclear imaging (FDG-PET)	Detection of neuroendocrine tumors and extracardiac disease

1.1 Primary vs. Secondary Tumors¶

Primary tumors arise de novo in the heart; secondary tumors result from metastasis. Primary tumors are rare (~1 in 2000 patients), while secondary involvement occurs in ~20% of patients with end-stage cancer. Myxomas are the most common primary tumor, while sarcomas are the most common malignant type.

1.2 Familial Syndromes¶

Familial myxomas are associated with Carney complex (autosomal dominant), characterized by cardiac, cutaneous, and endocrine manifestations. PRKAR1A gene mutations are implicated in ~70% of cases.

2. EPIDEMIOLOGY¶

Primary cardiac tumors are rare (~1 in 2000 patients), with myxomas accounting for ~75% of cases. Atrial myxomas peak in the third through sixth decades, with female predilection. Familial myxomas occur in ~10% of cases, often as part of Carney complex. Secondary tumors are more common in patients with end-stage metastatic cancer (20% prevalence).

2.1 Demographics¶

Atrial myxomas peak in 3rd–6th decades, female predominance. Rhabdomyomas are common in infants (often associated with tuberous sclerosis). Sarcomas are more common in adults, with a male predominance.

2.2 Risk Factors¶

Genetic predisposition (Carney complex, tuberous sclerosis), radiation exposure, and chronic inflammation may contribute. Secondary tumors are associated with metastatic cancer.

3. ETIOLOGY & PATHOPHYSIOLOGY¶

Myxomas are benign, gelatinous tumors composed of myxoma cells in a glycosaminoglycan-rich stroma. Familial cases are linked to PRKAR1A mutations. Sarcomas are malignant, with angiosarcoma being the most common adult type and rhabdomyosarcoma the most common pediatric type. Secondary tumors result from metastasis.

3.1 Molecular Basis¶

Familial myxomas (Carney complex) involve inactivating PRKAR1A mutations. Tuberous sclerosis-associated rhabdomyomas are linked to TSC1/TSC2 mutations. Sarcomas may involve PTCH1 or other tumor suppressor genes.

3.2 Pathogenesis¶

Myxomas arise from mesenchymal cells; sarcomas from malignant transformation. Embolic risk is due to tumor fragmentation or thrombus formation. Constitutional symptoms result from cytokine release (e.g., IL-6).

4. CLINICAL FEATURES¶

Common presentations include obstructive symptoms (mitral valve obstruction), embolic phenomena (stroke, myocardial infarction), constitutional symptoms (fever, weight loss), and arrhythmias. A characteristic 'tumor plop' may be heard on auscultation. Myxomas may cause paradoxical embolism or mimic endocarditis.

4.1 Obstructive Symptoms¶

Mitral valve obstruction (tumor prolapse), left ventricular outflow tract obstruction, or pulmonary stenosis. Symptoms may be positional due to gravity-dependent tumor displacement.

4.2 Embolic and Constitutional Symptoms¶

Embolic events (e.g., stroke, peripheral artery occlusion) due to tumor fragments. Constitutional symptoms (fever, cachexia) result from cytokine release (e.g., IL-6).

5. DIFFERENTIAL DIAGNOSIS¶

Constrictive pericarditis, restrictive cardiomyopathy, valvular heart disease, and cardiac masses (e.g., thrombus, vegetation). Myxomas may mimic mitral valve prolapse or endocarditis. Familial tumors may overlap with Carney complex or tuberous sclerosis.

5.1 Cardiac Masses¶

Differentiate from thrombus (nonmobile), vegetation (infective endocarditis), or inflammatory myofibroblastic tumors. Echocardiography and MRI are critical for distinction.

5.2 Systemic Syndromes¶

Carney complex (myxomas + lentigines + endocrine overactivity) vs. tuberous sclerosis (rhabdomyomas + seizures + renal angiomyolipomas).

6. INVESTIGATIONS & DIAGNOSIS¶

Echocardiography (TTE/TEE) is the initial modality for tumor localization. MRI provides detailed tissue characterization. CT evaluates calcifications and extracardiac involvement. FDG-PET may detect neuroendocrine tumors. Pericardiocentesis and biopsy are used for constrictive pericarditis differentiation.

6.1 Imaging Algorithms¶

Start with TTE for tumor location and size. 2. Use MRI for tissue characterization and differentiation from thrombus. 3. CT for calcifications and extracardiac assessment. 4. FDG-PET for neuroendocrine tumors. 5. Biopsy for constrictive pericarditis confirmation.

6.2 Diagnostic Criteria¶

Myxoma diagnosis requires echocardiographic visualization of a mobile, gelatinous mass with a stalk. Sarcomas are diagnosed via histopathology. Secondary tumors are confirmed by metastatic cancer history.

7. MANAGEMENT & TREATMENT¶

Surgical excision is the definitive treatment for all myxomas and most benign tumors. Malignant sarcomas require resection with chemotherapy. Embolic prophylaxis (anticoagulation) is used for high-risk patients. Asymptomatic small tumors may be monitored, but excision is recommended for any tumor >1 cm.

7.1 Surgical Considerations¶

Cardiopulmonary bypass is required for excision. Complete resection is critical to prevent recurrence. Preoperative coronary angiography is recommended for patients >50 years.

7.2 Chemotherapy¶

Neoadjuvant and adjuvant chemotherapy is used for sarcomas. For tuberous sclerosis-associated rhabdomyomas, surgical resection is preferred over medical management.

8. PROGNOSIS & COMPLICATIONS¶

Myxomas have an excellent prognosis with complete excision. Recurrence occurs in 12–22% of familial cases but <2% of sporadic cases. Complications include embolism, valvular dysfunction, and cardiac tamponade. Sarcomas have poor prognosis due to rapid progression and metastasis.

8.1 Complications¶

Embolic events (stroke, peripheral artery occlusion), valvular damage, arrhythmias, and sudden cardiac death. Myxomas may cause paradoxical embolism via right-to-left shunts.

8.2 Prognostic Factors¶

Complete resection improves outcomes. Sarcomas with metastasis have a median survival of <1 year. Familial myxomas require lifelong surveillance for new tumors.

9. SPECIAL CONSIDERATIONS¶

Pediatric cases (rhabdomyomas in tuberous sclerosis) require early surgical intervention. Pregnancy may complicate management due to increased cardiac workload. Elderly patients with comorbidities require careful risk-benefit analysis for surgery. Carney complex patients need multidisciplinary care for endocrine and cutaneous manifestations.

9.1 Pediatric Considerations¶

Rhabdomyomas in infants often regress spontaneously but may require resection if obstructive. Tuberous sclerosis-associated tumors are linked to seizures and renal angiomyolipomas.

9.2 Pregnancy¶

Myxomas may increase risk of paradoxical embolism. Anticoagulation is used cautiously due to bleeding risks. Surgical excision is recommended before pregnancy in symptomatic patients.

10. KEY POINTS & CLINICAL PEARLS¶

Atrial myxoma is the most common primary cardiac tumor; surgical excision is curative.
Use multimodal imaging (TTE, MRI, CT) for diagnosis.
Embolic risk is highest in myxomas and sarcomas; anticoagulation may be required.
Familial myxomas (Carney complex) require genetic counseling.
Complete resection is critical to prevent recurrence and complications.
Sarcomas have poor prognosis; early multidisciplinary management is essential.