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An unusual case of multiple infarcts

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Q1: What are the differential diagnoses before imaging?

Conditions which may present as a simultaneous stroke and apparent myocardial infarction include subarachnoid haemorrhage, a vasculitis (such as polyarteritis nodosa), drug abuse (for example, cocaine, ecstasy), infective endocarditis, mechanical valve failure, and cardiac tumours. Although coronary arterial embolism is a recognised complication of left sided cardiac tumours simultaneous myocardial and cerebral infarction from such lesions is very rare.1,2

Q2: What does the echocardiogram show (see p 431)?

Echocardiography revealed a large pedunculated tumour arising from the left atrium. The typical features can be seen of the tumour obstructing the mitral orifice at diastole. Doppler echocardiography demonstrated a degree of associated mitral incompetence.

Q3: What is the final diagnosis?

Cerebral and myocardial infarcts due to emboli (either thrombus or tumour fragments) arising from a large left sided cardiac tumour—an atrial myxoma.

Atrial myxoma is the commonest primary cardiac tumour. It may occur at any age but is most common in middle age. The prevalence is estimated at up to five per 10 000 from autopsy series, with a 2:1 female preponderance. Much fewer are recognised during life with an estimated prevalence of two per 100 000 in the general population. They are usually solitary, pedunculated, and typically occur in the left atrium, arising from the interatrial septum near the fossa ovalis.

Myxomata may present with obstructive, embolic, or constitutional manifestations. Most commonly it may mimic mitral valve disease, both stenosis (due to tumour obstruction of valve orifice) and regurgitation (due to valve trauma). The symptoms and signs may be positional in nature, and classically a “tumour plop” (a low pitched sound during early/mid-diastole) is heard. It should be noted, however, that as a cause of left atrial obstruction, myxomata are approximately 200 times less common than mitral stenosis. Embolic phenomena occur in 40% and may be simply thrombus or contain tumour. Constitutional effects include fever, weight loss, Raynaud’s phenomenon, finger clubbing, anaemia, polycythaemia, thrombocytopenia, leucocytosis, a raised erythrocyte sedimentation rate, and raised immunoglobulin levels. It is therefore often misdiagnosed as conditions such as endocarditis, connective tissue disorders, and non-cardiac malignancy.

Q4: What is the treatment?

Surgical resection is almost mandatory. Ideally this should be an urgent elective procedure. This case necessitated emergency resection within 24 hours of presentation. At surgery a very large gelatinous tumour mass (7 × 6 × 5 cm) was removed from the inferior margin of the fossa ovalis and the inferior wall of the left atrium. Histology showed an extensively myxoid stroma (fig 3; see p 431). Immunohistochemistry was positive for CD34, S100, neuron specific enolase, and vimentin consistent with a diagnosis of atrial myxoma.

Q5: What is the prognosis?

Surgical resection is usually successful, with a mortality rate <3% for elective procedures, but higher for emergency resections. The main perioperative risks are embolisation to the cardiac or cerebral circulation. Rarely the tumours recur.3 The patient described improved rapidly after surgery and made an excellent neurological and cardiological recovery.

Q6: Is there any risk to her children?

Autosomal dominant inheritance of atrial myxomata may occur as part of Carney’s syndrome, characterised by multiple myxomata (from anywhere in the heart, and elsewhere), lentiginosis, and various endocrine hyperactivity.4 In contrast the patient described here had a typical sporadic myxoma.

Q7: How could the diagnosis have been made earlier?

In this case the degree of haemodynamic embarrassment pointed towards the need for emergency reperfusion of the heart by angioplasty. Cardiac catheterisation and coronary angiography were therefore performed and provided the diagnosis almost by serendipity. However, in the context of a simultaneous stroke and myocardial infarction, early transthoracic echocardiography should be performed since this has a high degree of sensitivity and specificity, and is applicable even in critically ill patients. Coronary angiography would still be required in the work up for surgical resection if the presence of a left atrial myxoma was confirmed.

Final diagnosis

Atrial myxoma.

References

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