Left Main Coronary Artery Embolus

Abstract

The usual cause of left main coronary artery obstruction is atherosclerotic occlusion resulting from plaque rupture and subsequent thrombus formation. In previously reported cases, tumor embolization into the coronary arteries caused sudden death and was detected only at autopsy. Herein, we report an unusual presentation of cardiac papillary fibroelastoma of the aortic valve in a 62-year-old man. The fibroelastoma caused a left main coronary artery embolus and symptoms of acute coronary syndrome. The fibroelastoma was successfully excised during a valve-sparing surgical procedure. We believe that this is the 1st report of tumor embolization to the left main coronary artery—and in a living patient.

Papillary fibroelastomas are histologically benign neoplasms. These avascular tumors are small (mean diameter, 3–10 mm) and almost always occur singly. Often, they are mobile and have a thin stalk.¹ They have multiple papillary fronds, so that they resemble sea anemones. Papillary fibroelastomas consist of a core of dense connective tissue, an intermediate layer of loose connective tissue, and a covering of hyperplastic endothelial cells. Although cardiac papillary fibroelastoma is rare, it is the 2nd most common primary benign cardiac tumor (myxoma has been reported more often),² and it is the most common primary tumor of the heart valves. As with myxoma, its origin is not clear. Papillary fibroelastomas can develop on any cardiac valve or cardiac endothelial surface.³ Most are diagnosed incidentally.

Clinical manifestations of cardiac papillary fibroelastomas include syncope, angina pectoris, transient ischemic attack, stroke, myocardial infarction, pulmonary embolism, congestive heart failure, and sudden death. Coronary ischemia has been caused by the prolapse of pedunculated coronary cusp tumors into the coronary ostia,⁴ and, alternatively, by the direct embolization of organized thrombus from a cusp lesion to a coronary artery.^3,5 In previously reported cases,^5-7 tumor embolization into the coronary arteries caused sudden death and was detected only at autopsy. Here, we present the case of a patient who presented with symptoms of acute coronary syndrome. The diagnosis was a left main coronary artery (LMCA) embolus from a cardiac papillary fibroelastoma.

Case Report

In May 2008, a 62-year-old man with no known medical risk factors presented with symptoms of acute coronary syndrome. An electrocardiogram showed transient ST-segment elevation in the anterior leads that reverted within 2 hours. The patient's cardiac enzyme levels were normal. An echocardiogram showed moderate left ventricular (LV) dysfunction with hypokinesia of the anterior and lateral walls of the LV. Coronary angiography revealed that the LMCA and left anterior descending coronary artery were partially obstructed and that the right coronary artery and left circumflex coronary artery were normal (Fig. 1). The patient was placed on oral warfarin therapy and was discharged from the hospital. No thrombolytic agents were prescribed.

Fig. 1 Coronary angiogram of the left main coronary artery shows a filling defect—a possible tumor embolus.

In February 2009, the patient presented with excessive fatigue and sweating of 1 month's duration. He had not experienced fever or recurrent angina. On evaluation, he was afebrile, and findings on cardiac examination were normal. Blood and biochemistry test results were within normal limits. The results of electrocardiography and chest radiography were normal. An echocardiogram showed a 19 × 8-mm mobile pedunculated structure attached to the left and right coronary cusps of the aortic valve, no aortic stenosis or regurgitation, and moderate LV dysfunction with hypokinesia of the septum, anterior wall, and apical lateral wall (Fig. 2).

Fig. 2 Two-dimensional echocardiogram shows a pedunculated structure on the aortic valve cusp (arrow).

Because conventional coronary angiography was contraindicated, 128-slice computed tomography was used to delineate the exact morphology of the lesion and to evaluate the anatomy of the coronary arteries. It showed a 15 × 10-mm mobile mass attached to the left coronary cusp; the LMCA and the other coronary arteries were normal (Fig. 3).

Fig. 3 A 128-slice computed tomogram shows a lesion on the left coronary cusp of the aortic valve, and normal coronary arteries.

The patient underwent excision of the aortic valve tumor. After midline sternotomy, conventional cardiopulmonary bypass was instituted, and a right superior pulmonary vein vent was placed. After hypothermic fibrillatory arrest was established, the aorta was cross-clamped and then opened by low transverse incision. A small papillomatous lesion was attached to the rim of the left coronary cusp of the aortic valve. The LV outflow tract and mitral valve leaflets were normal, and no other lesion was seen (Fig. 4).

Fig. 4 Intraoperative photograph shows a papillomatous lesion on the rim of the left coronary cusp of the aortic valve.

The lesion was completely shaved from the left coronary cusp. The aortic valve leaflets were preserved with no regurgitation. The coronary ostia were normal. Histopathologic results were consistent with papillary fibroelastoma of the aortic valve (Fig. 5). The patient's postoperative course was uneventful, and he was doing well at his 1-year follow-up examination.

Fig. 5 Photomicrograph shows a central core of dense connective tissue that is covered by hyperplastic endothelial cells, consistent with papillary fibroelastoma (H & E, orig. ×400).

Discussion

Although cardiac papillary fibroelastomas can develop on the endothelial surface of the heart, most are attached to valves, chiefly the aortic valve¹; the mitral, tricuspid, and pulmonary valves are less often involved.⁸ When the tumors are attached to the aortic side of the aortic valve, dynamic coronary ostial obstruction can lead to myocardial ischemia. Fibroelastomas of the left side of the heart have been frequently associated with serious cardiovascular and neurologic symptoms.

These tumors may provide a nidus for a platelet fibrin clot that subsequently embolizes.^9,10 To the best of our knowledge, all reported cases of coronary emboli due to aortic papillary tumors resulted in sudden death, and all were necropsy findings: we found no reports of a cardiac papillary fibroelastoma that caused a LMCA embolus in a patient who survived. Plaque rupture with subsequent thrombus formation (atherothrombosis) is the most common cause of LMCA obstruction. Our patient had an unusual presentation of a coronary embolus that was caused by a tumor, which was detected later.

To circumvent problems that are associated with conventional angiography in patients who have potentially fragile aortic valve tumors, transesophageal echocardiography or 128-slice computed tomography can be used noninvasively to evaluate the nature of lesions and determine the status of the coronary arteries. During valve-sparing tumor excision of an aortic valve lesion, fibrillatory arrest is a very useful method of myocardial protection (as is retrograde cardioplegia).

The optimal surgical procedure for treating pedunculated cardiac papillary fibroelastoma is valve-sparing resection with thorough inspection of all areas during primary surgery.¹¹ Although thrombi have been reported on the surface of tumors, there are no guidelines regarding the use of anticoagulant or antiplatelet therapy.¹² Surgical resection is recommended when the tumor is mobile or pedunculated, increases in size, or causes symptoms. In asymptomatic patients, excision is prudent if the tumor involves the left-sided heart valves. Prophylactic anticoagulation therapy should be initiated in order to guard against thrombi until the patient can undergo surgical resection. Although tumoral regrowth is rare after surgical excision, long-term follow-up is essential.