Cardiac Fibroblastoma Presenting as NSTEMI

Abstract

Background

Myocardial infarction with nonobstructive coronary arteries (MINOCA) represents ∼8% of acute myocardial infarctions, with causes including myocarditis, coronary spasm, and embolization from cardiac tumors.

Case Summary

A 59-year-old woman presented with exertional chest pain and elevated troponins, consistent with non–ST-segment elevation myocardial infarction. Coronary angiography showed normal coronaries. Cardiac magnetic resonance imaging revealed a small ischemic infarct, prompting review of prior computed tomography, which identified a small aortic valve mass. Transesophageal echocardiography confirmed a mobile lesion. Surgical excision revealed a benign fibroblastoma, an extremely rare cardiac tumor.

Conclusions

This case highlights the importance of thorough imaging review in MINOCA and expands the spectrum of cardiac tumors implicated in coronary embolization. This is to our knowledge one of the first reports of a cardiac fibroblastoma.

Visual Summary

History of Presentation

A 59-year-old healthy woman with a family history of coronary artery disease presented to the emergency room with a report of exertional chest pain, which lasted for 4 hours. She also reported a prior history of substernal nonradiating chest pain that exacerbated on walking long distances and climbing stairs. She endorsed occasional alcohol use and denied smoking and illicit substance use. She was on finasteride owing to postmenopausal hair loss. In the emergency room, vital signs were significant for elevated blood pressure at 144/90 mm Hg; other vitals were within normal limits. Her physical examination was unremarkable.

Past Medical History

The patient had no significant medical history.

Differential diagnosis

Considerations included myocardial infarction, pulmonary embolism, and pneumothorax.

Investigations

Electrocardiogram showed normal sinus rhythm. Blood work-up was normal except for abnormally elevated high-sensitivity troponin at 339 ng/L that trended up to 997 ng/L. The electrocardiogram showed normal sinus rhythm, with no ischemic changes. Chest x-ray was unremarkable, and there was no acute cardiopulmonary process. Computed tomography pulmonary embolism protocol (Figure 1) ruled out pulmonary embolism. Echocardiography showed normal left ventricular ejection fraction, wall motion, and heart valves.

Figure 1.

Computed Tomography Angiography Showing a Filling Defect of the Aortic Side of the Aortic Valve (Arrow)

Management

A diagnosis of non–ST-segment elevation myocardial infarction was made, and the patient was started on goal-directed medical therapy with a plan for early invasive angiography. A coronary angiogram revealed normal coronaries with no evidence of coronary dissection. At that time, our differential diagnoses were stress cardiomyopathy, myocarditis, embolization, thrombophilia, or myocardial infarction with a normal coronary artery. Hence, immunological and hypercoagulable work-ups were obtained, but they were unremarkable. Cardiac magnetic resonance imaging (CMR) (Video 1, Figure 2) ruled out any evidence of cardiac inflammation; however, it showed a small region (1-2 myocardial segments) of near-transmural subendocardial and mid-myocardial delayed enhancement in the anterior apex, compatible with ischemic infarct and mild distal anterior wall hypokinesis. Upon retrospective review of the computed tomography scans for pulmonary embolism, a filling defect on the aortic side of the aortic valve was found, suggestive of a possible mass of uncertain etiology. There was a high suspicion of distal embolization resulting in myocardial infarction, and transesophageal echocardiography (Figure 3) demonstrated a small mass suspicious of fibroelastoma. The patient was subsequently discharged on apixaban and dual antiplatelet therapy, with close follow-up with cardiothoracic surgery as an outpatient.

Figure 2.

Cardiac Magnetic Resonance Imaging Depicting Area of Apical Hypokinesis and a Small Infarct (Arrow)

Figure 3.

Transesophageal Echocardiography Showing the Mass (Arrow)

Outcome and Follow-Up

Upon follow-up with cardiothoracic surgery, the decision for minimally invasive surgery was decided. Intraoperatively, the tumor was friable and delicate with a frond-like appearance. It was approximately 0.5 cm in diameter and was attached by a thin stalk to the left coronary cusp along the coaptation line with the noncoronary cusp. On gross examination, it was a red-tan soft tissue. Microscopic pathology (Figures 4 and 5) of the specimen revealed a benign fibroblastoma of the aortic valve.

Figure 4.

Hematoxylin and Eosin Stain on Histology

The aortic valve mass demonstrates numerous avascular branching papillary fronds with a proteoglycan-rich stroma lined by simple endothelium.

Figure 5.

Trichome Stain Highlights Dense Collagen Fibers Within the Cores

Discussion

Myocardial infarction with nonobstructive coronary arteries (MINOCA) is the presence of the universal acute myocardial infarction criteria, absence of obstructive coronary artery disease (≥50% stenosis), and no overt cause for the clinical presentation at the time of angiography.¹ Among 806,851 consecutive patients with acute myocardial infarction, the prevalence of MINOCA was estimated at 8.1%.²

The common causes of MINOCA are myocarditis, coronary microvascular dysfunction, Takotsubo cardiomyopathy, spontaneous coronary artery dissection, coronary spasm, or coronary artery embolization. Atrial fibrillation, cardiac tumors, prosthetic valves (mainly mechanical prostheses), and endocarditis are the usual culprits for coronary artery embolization. The diagnostic approach toward MINOCA is centered around CMR, per European Society of Cardiology guidelines.³ In our patient, CMR was performed with suspicion of myocarditis, which led to the discovery of ischemic changes secondary to probable cardioembolization from the tumor. With a revised differential, initial imaging was revisited to find the culprit tumor. Many leading cardiac societies recommend intracardiac imaging, including transesophageal echocardiography when clinically indicated, in patients with MINOCA with suspected cardioembolic mechanisms, such as atrial fibrillation, intracardiac thrombus, or paradoxical embolism.^1,4,5

Our first differential diagnosis, papillary fibroelastoma, well known to cause embolism, is the second most common cardiac tumor.⁶ However, histopathology unveiled a baffling result. Fibroblastomas—benign, fibrous soft tissue tumors—mainly occur in the subcutaneous tissues or skeletal muscle. There are only a few reports describing fibroblastomas within the heart.^7,8 Cardiac tumors may present with constitutional, thromboembolic, paraneoplastic, or mass effect–related symptoms. Once a cardiac mass is suspected (generally after transthoracic echocardiography), patients may undergo CMR for further evaluation of the mass. It also provides information about the extracardiac structures and their surrounding anatomy, which is often helpful in surgical planning.⁹ Depending on the size and symptom burden of the tumor, surgical excision is offered to the patient. Despite limited supporting data, if surgery is not undertaken given high surgical risk or patient preference, treatment with antiplatelet agents may be considered.¹⁰

In our case, we wish to highlight how reviewing initial imaging can be pivotal to diagnosis in cases of MINOCA. We also describe to our knowledge one of the initial instances of a fibroblastoma, typically located in skeletal muscle, to be discovered in the heart.

Conclusions

Fibroblastomas are exceedingly rare benign tumors, most often arising in skeletal muscle or subcutaneous tissue and only rarely reported within the heart. Their presentation as a cause of MINOCA is exceptionally uncommon, making prompt recognition challenging.

Visual Summary.

Overview of the Clinical Course, Highlighting Key Diagnostic Steps, Imaging Findings, and Treatment Decisions

CMR = cardiac magnetic resonance imaging; CTPE = computed tomography pulmonary embolism; CXR = chest x-ray; DAPT = dual antiplatelet therapy; ECHO = echocardiography; EKG = electrocardiogram; MINOCA = myocardial infarction with nonobstructive coronary arteries; TEE = transesophageal echocardiography.

Funding Support and Author Disclosures

The authors have reported that they have no relationships relevant to the contents of this paper to disclose.

Take-Home Messages

• •Keep a broad differential in MINOCA, including rare cardiac tumors, especially when initial investigations are inconclusive.
• •Reviewing prior imaging with a fresh diagnostic perspective can be pivotal in identifying unusual causes of myocardial infarction.

Appendix

Video 1

Cardiac Magnetic Resonance Imaging Depicting Area of Apical Hypokinesis and a Small Infarct (Arrow)