Interventricular septum mass presenting as a late acute coronary syndrome with ST-segment elevation: a case report.

BACKGROUND: Intracardiac masses are relatively rare but the diagnosis can be challenging for the cardiologist and the clinical presentation can be misleading. While most of the cardiac masses are benign, malignant masses are mostly metastatic tumours. CASE
SUMMARY: An 81-year-old man was admitted to the cardiology department for congestive heart failure with the complaint of recent dyspnoea. The initial electrocardiogram was suggestive of a late presentation of an anterior myocardial infarction. Blood test showed mild and stable elevation of troponin and brain natriuretic peptide. Doppler-echocardiography revealed an interventricular septal thickening. Contrast echocardiography revealed a mass with a possibly necrotic centre and peripheral hypervascularization. Cardiac computed tomography (CT) confirmed the existence of a cardiac tumour with a hypodense centre and also revealed the presence of a large tumour of the lung's left lower lobe with multiple enlarged lymph nodes associated with possible left adrenal gland metastasis. Computed tomography-guided percutaneous biopsy of the pulmonary mass demonstrated a squamous cell lung cancer which was likely the primary cancer. The patient was discharged home waiting for chemotherapy to start but died a few days later at home of an unknown cause. DISCUSSION: Diagnosis of intracardiac mass is difficult, often requiring multiple imaging modalities. Contrast-enhanced echocardiography may help early diagnosis and can be easily implemented with other imaging modalities such as cardiac magnetic resonance imaging or CT.

Intracardiac masses are a challenging diagnosis, often multimodal, with wide therapeutic implications (from abstention to cardiac surgery).

Diagnostic accuracy of standard echocardiography can be easily enhanced at the bedside with a contrast agent, and an even greater amount of information can be obtained by a myocardial perfusion study which can be processed at the same time by lowering the mechanical index.

Not all ST-segment elevation is an indication of ischaemia and differential diagnosis should be evocated when the presentation is atypical.

Introduction

Intracardiac tumours are relatively rare and more often benign. Among malignant tumours, metastatic tumours are the most common neoplasm of the heart.,

The clinical presentation ranges from asymptomatic to dyspnoea, chest pain, or arrhythmia.

Transthoracic echocardiography (TTE) is the first-line examination tool and can assess intracardiac masses with a diagnostic sensitivity of 93.3%. Its performance can be enhanced by the addition of a contrast agent, helping to better discriminate endothelial borders, myocardium and may help to better characterize the myocardial tumour.

However, initial diagnosis may be difficult and is often multimodal thanks to other cardiac imaging techniques such as cardiac magnetic resonance imaging (CMR) and computed tomography (CT)-scan.

Authors report here an atypical case of lung cancer with cardiac metastasis presenting initially as a late acute coronary syndrome.

Case presentation

An 81-year-old man, former smoker, was admitted to our cardiology department for congestive heart failure with the complaint of recent onset of dyspnoea. He had a history of ischaemic heart disease with stenting of the mid-left anterior descending artery. Two months before his admission, the patient received an implantable cardioverter-defibrillator (ICD) for sustained ventricular tachycardia.

Upon arrival, blood pressure was 130/70 mmHg, heart rate 72 b.p.m., and oxygen saturation 95% with 3 L/min of oxygen. Physical examination demonstrated signs of decompensated heart failure with no evidence of any heart murmur.

The initial electrocardiogram (ECG) (Figure ) showed a sinus rhythm with abnormal R-wave progression and ST-segment elevation in leads V2–V5 and II, III, aVF, suggesting a late presentation of an acute myocardial infarction. The previous ECG, performed 2 months before, showed only negative T-waves in V2–V3 with normal R-wave progression (Figure ).

Twelve-leads electrocardiogram performed 2 months before the event (A) showing negative T-waves in V2–V3 and at the time of presentation (B) showing abnormal R-waves progression in precordial leads, ST-segment elevation and negatives T-waves in anteroseptal, and inferior territories.

Blood tests demonstrated mild elevation of cardiac enzymes with ultrasensitive troponin I at 83 ng/L (normal <26 ng/L) and brain natriuretic peptide at 1400 pg/L (normal <100 pg/L). A moderate systemic inflammatory response syndrome was noted with an elevated C-reactive protein at 93 mg/L (normal <4 mg/L) and white blood cell counts at 14 G/L (normal <10 G/L).

As coronary angiography 2 months before, prior to his ICD implantation, had shown no new significant stenosis, it has been decided not to perform an emergency coronary angiography.

Transthoracic echocardiography (TTE) was performed and showed a known impaired left ventricular ejection fraction of 40% due to inferior and posterior wall akinesia. Transthoracic echocardiography also demonstrated a thickening or a mass of the apical and median portion of the interventricular septum (IVS) (Video 1, Figure ) measured 5 cm × 3 cm, associated with moderate pericardial effusion. Contrast-enhanced TTE using low mechanical index (MI) imaging settings (MI at 0.23) revealed a myocardial mass involving the apex of both left and right ventricles (Video 2, Figure ). Mechanical index was then decreased to 0.07 with an intermittent flash of a high mechanical index to assess the vascularization of the tumour (Video 3), demonstrating a peripheral contrast enhancement suggestive of a necrotic centre with peripheral hypervascularization, consistent with a myocardial malignant tumour (Figure ).

Transthoracic echocardiography, apical four-chamber view without contrast agent (A) of the mass (arrows), after contrast injection using low mechanical index (B), and late perfusion using very low mechanical index (C) suggestive of a necrotic central area (arrow).

To better characterize the cardiac mass, cardiac CT was preferred as a second line exam to CMR, considering the recent ICD implantation. An ECG-gated cardiothoracic contrast-enhanced CT-scanner was performed (Figure ) demonstrating an important thickening of the apical part of the IVS at the arterial phase (Figure ) and moderate pericardial effusion. Delayed acquisition at 2 min confirmed an intra-septal apical mass of 6 cm × 4 cm × 8 cm with a hypodense centre and peripheral enhancement consistent with the diagnosis of a malignant tumour with a necrotic central area (Figure ).

Axial views of the cardiac electrocardiogram-gated computed tomography scanner of the patient, without contrast (A), at arterial phase (B) and 2 min (C) after iodine contrast media injection. Moderate pericardial effusion (thick arrow) is seen mostly next to the lateral left ventricular wall (A–C). Slightly spontaneously hypodense (A) apical mass (thin arrow) inducing a thickening of the interventricular septum is demonstrated (B) with a central necrotic hypodense component at the delayed phase (C). Interestingly on the same slice a voluminous suspicious lower left lobular pulmonary mass of 9 cm × 6 cm is demonstrated (*).

Interestingly, cardiac-CT also revealed a voluminous mass of the lung’s left lower lobe (LLL) measured at 9 cm × 6 cm with multiple mediastinal lymph nodes and a possible left adrenal gland involvement. Computed tomography-guided percutaneous biopsy of the LLL mass demonstrated a squamous cell lung cancer (Figure 4).

Figure 4

Computed tomography-guided percutaneous biopsy of the left lower lobe mass (A) haematoxylin and eosin stain showing extensive tumoral infiltration (★) with low (B) and high magnification (×200) with cells with large eosinophilic cytoplasm and intercellular bridges (C). Positive immunostaining of P40 antigen confirming the squamous nature of the tumour (D) (arrow, brown coloration).

The final diagnosis was a Stage IVB (according to the Union for International Cancer Control) large squamous cell lung cancer possibly spreading to the heart and the left adrenal gland.

The signs of decompensated heart failure resolved after low-dose intravenous furosemide therapy and the patient was discharged home before chemotherapy with Carboplatin and Paclitaxel. He unfortunately died 2 days later at home from an unknown cause. We could not perform autopsy nor device interrogation because of the family’s opposition to further investigate the cause of death.

Discussion

Incidental finding of a cardiac mass is challenging for cardiologists. Initial transthoracic echocardiography plays a central role and therapeutic consequences may range from conservative management to more invasive management, i.e. cardiac surgery.

The prevalence of cardiac tumours in the general population is very low, estimated between 0.001 and 0.3% in autopsy studies. About three out of four are benign tumours including myxoma, fibroelastoma, and lipoma. Malignant tumours are most frequently metastases, mostly from lung and blood cancer but remain often clinically silent and are often diagnosed post-mortem.,

In our report, the acute coronary syndrome (ACS) presentation of our patient was very atypical, even though, already described in the literature., Indeed, most cardiac masses are asymptomatic and are discovered during a routine examination or baseline echocardiography prior to chemotherapy, but our patient had no medical history of cancer. Nevertheless, some patients may present with dyspnoea, chest pain, ventricular arrhythmia, conduction disturbance or, similar to our patient, mimic an acute myocardial ischaemic event., Previous explanations have been proposed to better understand ACS presentation, including inflammation and potassium abnormalities inside and around the tumour and mechanical stress on fibres adjacent to the tumour mimicking ischaemic ECG patterns., In our case, we hypothesized that the electric abnormalities could be explained by the intra-tumoral necrosis.

Standard TTE is the first-line test enabling mass detection and providing information about its localization (pericardial, intramyocardial, or intracavitary), size, mobility, shape, echogenicity, and its relationship with other structures at the bedside.

The use of additional contrast agents may improve TTE performances enabling a better differentiation between different types of cardiac masses. In a prospective study aimed to assess the discrimination between thrombi, myxoma and malignant tumour, contrast echocardiography showed excellent sensitivity and specificity, improving interobserver variability. Both the European Association of Cardiovascular Imaging and the American Society of Echocardiography recommend the use of contrast echocardiography for the evaluation of intracardiac masses, in particular when MRI is unavailable., The use of contrast agent needs specific imaging settings including a low mechanical index (0.1–0.3) which are now widely available on all echocardiograms.

Using a very low mechanical index (near 0.1) after a high mechanical index flash, enable trained echocardiographers to assess tumoral vascularization and compare it with the adjacent myocardium. This may help to better discriminate between malignant and benign cardiac tumours, particularly when they are located inside the myocardium. Kirkpatrick et al. and Wang et al. demonstrated that by using semi-quantitative or quantitative measurements, operators could differentiate between malignant tumours (abnormal neovascularization, enhanced or hyper-enhanced tissular mass), benign tumours (poor vascularization, only partially enhanced), and thrombi and fibroelastoma (no vascularization at all).

Cardiac MRI and cardiac-CT are recognized modalities to characterize cardiac tumours. In our case, the presence of ICD limited the assessment by cardiac MRI. Cardiac CT-scanner confirmed contrast-enhanced echocardiography findings and more importantly, revealed a voluminous suspect pulmonary tumour with a high probability of adrenal gland metastasis.

Differential diagnoses have been suggested before contrast-enhanced TTE such as intracardiac thrombus and primitive hypertrophic cardiomyopathy, ruled out by the tumoral enhancement pattern of the mass after contrast injection. Haematoma from ischaemic or traumatic origin was also unlikely because of the perfusion pattern and the low levels of troponin.

Our case illustrates how a multimodality non-invasive approach using contrast perfusion echocardiography and cardiac-CT scanner enabled a rapid diagnostic shift from an acute coronary syndrome in a patient with no history of cancer to an unexpected cardiac metastasis of lung cancer.

Lead author biography

Lucas Coroyer graduated in medicine at Université de Paris in 2016 and is currently completing his internship in general cardiology in Paris.

Supplementary material

Supplementary material is available at European Heart Journal - Case Reports online.

Click here for additional data file.

Date	Events
Few years ago	Stress test is performed, showing anterior ischaemia. Coronary angiography demonstrated stenosis of the mid-left anterior descending artery and a calcified stenosis of the proximal circumflex artery. One drug-eluting stent was placed in the mid-left anterior descending artery.
Early October 2019	Sustained ventricular tachycardia. No new lesion on the coronary angiography. Implantable cardioverter-defibrillator implantation.
Mid-November 2019	One-month post-implantation consultation. No symptoms.
Late November 2019	Onset of moderate exertional dyspnoea
24 December 2019	Physician consultation for worsening of the dyspnoea. Electrocardiography shows anterior ST-segment elevation.
26 December 2019	Contrast-enhanced echocardiography reveals a mass of the septum wall. Computed tomography of the heart confirms the mass and shows voluminous pulmonary tumour.
30 December 2019	Computed tomography-guided percutaneous biopsy of the pulmonary tumour is performed. Pathology shows squamous cell lung cancer
03 January 2020	Patient is proposed with chemotherapy and discharged from hospital.
05 January 2020	Death from unknown cause.