Cardiac Mass Presenting as ST-Elevation Myocardial Infarction: Case Report and Review of the Literature

ABSTRACT: We discuss the case of a 71-year-old female patient who presented with findings suggestive of an acute myocardial infarction. Subsequent evaluation revealed an extrinsic cardiac mass encasing the left circumflex and right coronary arteries (RCA) which caused compression and spasticity of the RCA. Biopsy findings were consistent with a hematologic malignancy. Reports of extrinsic compression of epicardial coronary arteries are uncommon. Neoplasms, either primary cardiac tumors or metastatic disease, are a rare cause of extrinsic compression of coronary arteries. J INVASIVE CARDIOL 2008;20:628–630 Case Presentation A 71-year-old female presented to our institution with typical chest pain of 1 hour’s duration. Her past medical history was significant for hypertension, dyslipidemia, type II diabetes and tobacco use. She had been visiting a relative in the hospital when she began to experience substernal chest pain that was associated with nausea and diaphoresis and presented to our emergency department. Her initial electrocardiogram showed ST-elevation in the inferior leads and 2:1 atrioventricular block (Figure 1). She was treated with aspirin, morphine, nitroglycerin and unfractionated heparin and was sent for emergent cardiac catheterization and primary percutaneous intervention. Coronary angiography revealed a normal left coronary artery. The right coronary artery (RCA) showed severe diffuse narrowing of the distal vessel with extension to the bifurcation of the posterior descending artery (PDA) and posterolateral artery (Figure 2). Focal vasospasm was suspected because the remainder of the coronary tree appeared normal. The narrowing improved, but did not normalize after intracoronary nitroglycerin and verapamil administration. Low-pressure angioplasty for presumed refractory vasospasm was performed using a 7 Fr IMA guide and a Maverick 2.5 x 20 mm balloon (Boston Scientific Corp., Natick, Massachusetts) inflated to 2–4 atm. The proximal PDA and posterolateral artery also underwent angioplasty. The final outcome was defined as successful with minimal residual stenosis post intervention. The patient continued to experience chest pain and underwent an echocardiogram, which revealed an echodensity at the right atrium suspicious for a cardiac mass (Figures 3A and B). Cardiac magnetic resonance (CMR) imaging was performed and showed a cardiac mass involving the right atrium, tricuspid annulus and the atrioventricular groove with extension into the pericardium (Figures 4 and 5). CMR also showed enlarged mediastinal and right hilar lymph nodes as well as spinal lesions consistent with metastases. A computed tomography (CT)-guided biopsy of a spinal lesion was performed. The aspirate contained diffuse sheets of tumor cells with extensive necrosis. Immunoperoxidase stains were performed and showed the tumor cells to express the leukocyte common antigen (CD45). The B-cell marker CD 79a was also expressed focally and weakly. Other markers including CD3, vimentin, CD20, pankeratin, neuroendocrine markers (chromogranin and synatophysin) and a melanocytic marker (S100) were negative. Staining for kappa and lambda light chains was negative. The expression of CD45 is consistent with a hematolymphoid neoplasm. The differential diagnosis of a mass expressing the above-stated markers includes a plasma cell neoplasm or a lymphoma with plasmacytic differentiation.11 The patient was evaluated by our oncology services, which formulated plans for further therapy. She was discharged with plans to return to the oncology outpatient clinic. However, the patient decided not to pursue further care. Multiple attempts to persuade her failed. One month after discharge, the patient presented to a local hospital with acute shortness of breath, developed respiratory failure and expired. Discussion Our patient initially presented with findings thought to represent a classic acute myocardial infarction (AMI). Subsequent evaluation revealed a cardiac mass with encasement of the left circumflex and right coronary arteries and compression or spasticity of the RCA. Biopsy of a lumbar vertebral body lesion revealed a hematological malignancy. This case study is a rare, but interesting, presentation of ST-elevation myocardial infarction and is not to be considered a routine etiology of the clinical presentation of AMI. Coronary ischemia is usually due to preexisting coronary artery disease. Fewer than 5% of patients with AMI do not have atherosclerotic coronary disease. Reports of extrinsic compression of epicardial coronary arteries are uncommon. Neoplasms, either primary cardiac tumors or metastatic disease, can in rare cases cause extrinsic compression of coronary arteries.1 Pectus excavatum, disorders of the aortic root, coronary sinus aneurysms, enlarged pulmonary arteries and mediastinal tumors can also compress the coronary arteries.1–4 The RCA stenosis in our patient responded to vasodilators and low-pressure balloon inflations, suggesting that simple extrinsic compression was not the sole explanation for her angiographic stenosis. Potentially, mechanical factors from the mass coupled with local or systemic vasoactive mediators related to her malignancy, may have contributed to vasospasm at this site. Only about one-fourth of cardiac tumors are metastatic or invasive. Sarcomas and lymphomas are two of the most common non-metastatic malignancies. Cardiac sarcomas can display a variety of morphologies including angiosarcoma, rhabdomyosarcoma and fibrosarcoma, which likely reflect their mesenchymal origin. They usually occur in the third and fifth decades of life. In a small case series, mutations of K-ras were observed in most primary cardiac sarcomas. The clinical manifestations of these tumors depend on their location and the extent of intracavitary invasion.5–7 Rapid tumor growth predisposes patients to pericardial invasion and malignant pericardial effusion, with or without tamponade. Cardiac arrhythmias, conduction abnormalities and sudden death have all been reported. Transthoracic echocardiography (TTE) is useful for initial imaging, but transesophageal echocardiography (TEE), CT and CMR provide better depiction of tumor size, location and extent of invasion.5 Primary cardiac lymphomas involving only the heart are rare. These tumors are universally large B-cell lymphomas.8 In immunocompetent patients, the median age of presentation is 64 years, with a male-to-female predominance of 3:1. Affected patients can present with chest pain, heart failure, arrhythmias, pericardial effusion, hemodynamic instability secondary to tamponade and constitutional symptoms.5,9 TTE has only moderate sensitivity for cardiac lymphoma; TEE offers better diagnostic quality. Gallium-67 scans can show uptake in the heart, but findings are nonspecific. CMR seems to be the most sensitive of all imaging modalities, but the imaging findings at CMR (and CT) are non-specific.5,10 Sensitivities in the range of 14–67% have been reported for cytological analysis of pericardial fluid when malignant effusions are present. Transvenous endomyocardial biopsy has a sensitivity of 50%, with open biopsy being the gold standard.5 Median survival is less than 1 month without treatment. With chemoradiation therapy, the median survival increases to about 1 year.10 Long-term survival for patients with cardiac lymphoma is usually dismal, with arrhythmias, tumor lysis syndrome and cardiac rupture complicating therapy.11,12 Although rare, cardiac masses can extrinsically compress a coronary artery and cause an AMI. They should be considered in the differential diagnosis when the patient’s clinical picture does not correlate with the angiographic data. Echocardiography, MRI and CT imaging can provide useful diagnostic information on the existence, extent and likely prognosis of a cardiac neoplasm.

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