Large free-floating right atrial mass presenting as intermediate-high risk pulmonary embolism: is reperfusion a better definite strategy?
- 1 Cardiology Department, Hospital Garcia de Orta EPE, Almada, Portugal
- 2 Cardiovascular Center of the University of Lisbon, Lisbon, Portugal
- 3 Academic Medical Center of Lisbon, Faculty of Medicine, University of Lisbon, Lisbon, Portugal
- Correspondence to Professor Helder Pereira; hhpereira@gmail.com
Abstract
We present a woman in her 60s diagnosed with an intermediate-high risk acute pulmonary embolism and a large, non-serpiginous right atrial (RA) mass. Conservative therapy with unfractionated heparin was started and further assessment of the mass with cardiac MRI suggested thrombus as the most likely diagnosis. Despite 1 month of anticoagulation, mass size remained stable and surgical RA embolectomy and left pulmonary endarterectomy was performed. Histopathology confirmed thrombus. The patient died 10 weeks after surgery.
Background
Free-floating right atrial (RA) thrombi are rare in acute pulmonary embolism (PE) and are associated with increased early mortality, especially in patients with right ventricular dysfunction. Atypical non-serpiginous thrombi can be differentiated from other masses with a multimodality imaging approach, with cardiac magnetic resonance (CMR) being the gold standard method. Although not clear for haemodynamically stable patients, early first-line reperfusion therapy is potentially a more adequate strategy.
Case presentation
This is the case of a Caucasian woman in her 60s, with a medical history of obesity (body mass index 34 kg/m2) and allergic rhinitis for which she took cetirizine. She began a 2-week history of progressive fatigue and cough and was referred to our emergency department by her general physician due to dyspnoea and hypoxaemia. She denied fever, myalgias, headache, thoracic pain, presyncope or syncope, haemoptysis, palpitations or lower limb oedema. Besides obesity, she had no other predisposing factors for venous thromboembolism, no weight loss or anorexia, no night sweats and no gastrointestinal symptoms.
At admission, the patient was haemodynamically stable (blood pressure 150/96 mm Hg, heart rate 88 beats per minute), had polypnoea (respiratory rate of 29 cycles per minute) and required oxygen supplementation (fraction of inspired oxygen (Fio2) of 24%) for an arterial oxygen saturation of 90%–94%. She had no jugular venous distention and cardiac auscultation revealed arrhythmic heart sounds. Pulmonary auscultation was normal. Abdomen observation was normal, without distention, pain, palpable masses or organomegaly. Lower extremities were well perfused, and she had no signs of oedema or deep vein thrombosis.
Arterial blood gas was compatible with respiratory alkalosis with partial respiratory failure (Pao2/Fio2 ratio of 241) and lactates of 1.4 mmol/L. Blood tests showed increased d-dimers 1.54 µg/mL and N-terminal pro-B-type natriuretic peptide 1750 pg/mL with low high-sensitivity troponin T 19 ng/L. A 12-lead ECG revealed new-onset atrial fibrillation with no signs of right ventricular strain.
Investigation and treatment
Further investigation with thorax CT was performed in line with our hospital protocol for COVID-19 suspected patients. It was done without intravenous contrast due to history of atopy and revealed multiple and bilateral areas of pulmonary infarct. On suspicion of acute PE, ventilation/perfusion scintigraphy confirmed 30% of global pulmonary perfusion defects with preserved ventilation scan and immediate anticoagulation with weight-adjusted enoxaparin was started.
A second thorax CT with pulmonary angiography performed after a desensitisation protocol revealed extensive signs of bilateral PE, in central and lobar topography for the left and right pulmonary arteries, respectively. It also showed a single, large RA mass. It did not identify thoracic lymphadenopathies (figure 1).
CT pulmonary angiography confirming pulmonary embolism diagnosis. Axial slice at the level of pulmonary bifurcation showing enlarged pulmonary arteries and central left pulmonary thrombus (A) and a single right atrial mass at the level of the atria (B).
First transthoracic echocardiogram showed pulmonary artery distention associated with right chambers’ dilation and impaired right ventricle function, shown by a tricuspid annular plane systolic excursion of 12 mm and a fractional area change of 20%. Systolic flattening of the interventricular septum and a left ventricle eccentricity index above 1 (in systole and diastole) were also present suggesting pressure overload of right ventricle. Pulmonary systolic arterial pressure was estimated in 43 mm Hg. Furthermore, there was a large (4.0 × 3.1 cm), non-serpiginous and highly mobile RA mass, showing diastolic protrusion to the right ventricle, with a possible adhesion point to the coronary sinus ostium (figure 2, video 1).
Transthoracic echocardiogram (TTE) with a right atrial mass. Four-chamber view TTE showing the right atrial mass with a possible adhesion point to the coronary sinus ostium (A) and its dimensions (B).
Intermediate-high risk acute PE associated with a large RA mass was diagnosed. The pulmonary embolism response team was contacted, and due to haemodynamic stability and high embolisation risk for performing percutaneous catheter-direct treatment, a switch of anticoagulant therapy to unfractionated heparin perfusion was started and the response adjusted to achieve the target activated partial thromboplastin time. This decision was based on the possibility of imminent clinical deterioration. The patient maintained atrial fibrillation throughout hospital stay. Conversion to sinusal rhythm was not planned before the RA mass resolution due to fear of further embolisation.
Despite remaining haemodynamically stable and with progressive respiratory relief, subsequent transthoracic echocardiograms performed 1 week and 1 month after hospital admission revealed a decrease in pulmonary hypertension signs but no variation in the mass size. These findings, along with the absence of the typical serpiginous aspect of a thrombus, increased the suspicion of a neoplasia, namely a myxoma. Consequently, further assessment was performed aiming to better characterise the mass and posterior referral to surgery.
CT of the thorax, abdomen and pelvis was not suggestive of a possible metastatic origin for the mass. For the differential diagnosis of the mass, we performed cardiac MRI, that showed a 2.7 cm diameter mass, isointense in T1-weighted (and in T1 with fat suppression) and iso/hyperintense T2-weighted imaging, with no uptake in first pass and late gadolinium enhancement study (figure 3). It also confirmed the persistence of the left pulmonary artery thrombus. Positron emission tomography was not compatible with malignancy.
Cardiac MRI (slices at the level of the right atrium (RA)), with RA mass characteristics compatible with thrombus (arrows): hypointense in cine image (A); isointense in T1-weighted image (B) and T1 with fat suppression (C); iso/hyperintense in T2-weighted image (D); resting perfusion showing an absence of first-pass contrast enhancement (E); recovery image post gadolinium showing a mass with uniformly low signal which is a feature of thrombus (F).
Considering these characteristics, an atrial thrombus was the most likely diagnosis and the patient underwent surgical RA embolectomy and left pulmonary endarterectomy, under cardiopulmonary bypass (figure 4, video 2). The postoperative period was uneventful. Histopathology of the retrieved masses confirmed thrombus. Detailed workup for genetic and acquired causes of thrombophilia was not performed.
Retrieved masses of the right atrium (A) and the left pulmonary artery (B).
Outcome and follow-up
The patient was discharged 5 days after surgery, asymptomatic and under oral anticoagulation with edoxaban 60 mg, once daily. She had a booked surgery appointment 1 month after the intervention, which did not happen due to the COVID-19 contingency plan. She also had a booked appointment in our pulmonary embolism clinic to exclude post-PE syndromes and plan thrombophilia screening. However, the patient died 2 weeks before this consultation.
According to the patient’s family, although there was recurrence of progressive cough, dyspnoea and thoracic pressure after hospital discharge, she did not seek medical assistance due to fear of COVID-19 pandemic. She died suddenly 10 weeks after surgery in her home. Autopsy was not performed.
Discussion
Free-floating RA masses are a rare phenomenon in acute PE patients and are associated with increased early mortality.1 2 Although the most common causes of intracardiac masses are pseudotumours, such as thrombus or normal anatomic variants,3 a thorough investigation based on a multimodality imaging approach is essential to perform the differential diagnosis and guide therapeutic decisions.4 Considering its diagnostic value, CMR is now positioned as one of the methods of choice for the assessment of intracardiac masses,3 and the performance of CT and positron emission tomography add sensitivity and specificity to CMR findings.4 Despite the diagnostic accuracy of this approach, sometimes histopathology is the only way to achieve the definite diagnosis,4 especially (and as in this case) if the suspected cause is not responding to medical treatment.
Treatment of acute PE complicated with RA thrombi remains a matter of great debate given the absence of randomised clinical trials. According to the new 2019 European Society of Cardiology (ESC) guidelines for the diagnosis and management of acute PE, reperfusion treatment with fibrinolysis or surgical embolectomy becomes more intuitive for patients who present or develop haemodynamic instability.1 For haemodynamically stable patients, there is conflicting evidence regarding the best treatment strategies. While some studies suggest no significant differences of thrombolysis over anticoagulation,2 others suggest that in intermediate-high risk patients, anticoagulation alone might not be an adequate treatment.5–7 Furthermore, considering that both heparin and thrombolysis might potentiate the risk of further pulmonary or paradoxical embolisation, some authors propose surgical thrombectomy as the best management option in cases of isolated right chamber thrombus or its combination with patent foramen ovale, respectively.5 8 Recent reports have indicated favourable surgical outcomes in selected cases of intermediate-risk PE.1 Surgical treatment may be more suitable in cases of very large atrial thrombus9 and the results of embolectomy are better before the onset of cardiogenic shock.10
The recurrence of PE after surgical pulmonary embolectomy is estimated to be high, with studies reporting rates of 5%–7%11 12 and is associated with life-threatening outcomes in patients with previous RV failure.13 Given the risk of new embolic events, multiple centres are now advising the perioperative placement of inferior vena cava (IVC) filters because of its efficacy for the prevention of recurrent PE and 90-day mortality.11 13 It is nonetheless controversial if the filter should be retrieved and if so, the best timing to do so.13
In the present case, unfractionated heparin was started with the intention to better characterise the RA mass, but early surgical embolectomy and pulmonary endarterectomy might have been the best strategy considering findings of a large mobile thrombus, the proximal location of the pulmonary embolus, haemodynamic stability and the non-response to medical treatment. Also, looking back to our patient’s symptoms after surgery, she probably had recurrent PE, which makes us believe that a close surveillance is crucial in these patients. Moreover, we must consider that the exclusion of a thrombophilic condition was not possible because this investigation is more reliable 1 month after the acute event and also after oral anticoagulation suspension.14 15 Although the patient was given the recommended dose of edoxaban to prevent embolic events in atrial fibrillation and venous thromboembolism, and there is increasing evidence of direct oral anticoagulants efficacy for the treatment of intracardiac thrombus,16 its recommended dose for the management of an intracardiac mass is not well established. Therefore, perhaps anticoagulation with a vitamin K antagonist might have been more appropriate to prevent thromboembolism recurrence. Although it is still controversial to use IVC filters in patients with free-floating thrombi and no contraindication for therapeutic anticoagulation, we can argue that, in this particular case, the perioperative placement of an IVC filter could also have been an option to prevent early mortality.
In conclusion, this clinical case intends to illustrate that right chamber masses presenting with a pulmonary embolic event are associated with high in-hospital and postdischarge mortality and that there is still a great gap of evidence in terms of best therapeutic management and follow-up.
Learning points
-
In patients with suspected pulmonary embolism (PE) without haemodynamic instability, the diagnostic strategy should be based on clinical pretest probability.
-
Free-floating right chamber masses are a rare phenomenon in acute PE patients and are associated with increased mortality.
-
Cardiac magnetic resonance is considered the imaging technique of choice for the assessment of cardiac masses.
-
For haemodynamically stable patients with acute PE complicated with right chamber free-floating thrombi, there is a lack of consensus regarding the most adequate treatment strategy.
-
Particularly for intermediate-high risk patients with free-floating right atrial thrombus, early first-line reperfusion, specifically surgical thrombectomy, is potentially a more adequate strategy.
Ethics statements
Patient consent for publication
Footnotes
-
Contributors MM is the main author of this work and was involved in patient care, diagnosis and therapeutic discussion, and also in article conception, writing and literature review. RC and FF were involved in diagnosis and therapeutic discussion and also participated in article conception and review. HP participated in the case review.
-
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
-
Case reports provide a valuable learning resource for the scientific community and can indicate areas of interest for future research. They should not be used in isolation to guide treatment choices or public health policy.
-
Competing interests None declared.
-
Provenance and peer review Not commissioned; externally peer reviewed.
- © BMJ Publishing Group Limited 2022. No commercial re-use. See rights and permissions. Published by BMJ.
References
Use of this content is subject to our disclaimer