Clinical introduction
A man in his 50s was admitted for recurrent syncope over 4 months. ECG demonstrated sinus rhythm, peripheral low voltage and T wave inversions in V3–V6 (figure 1A). Holter ambulatory monitoring showed normal sinus rhythm with atrial and ventricular premature beats. Electroencephalogram was normal. N-terminal pro-brain natriuretic peptide was elevated at 4631 ng/L, and troponin-T was elevated at 105 ng/L. Coronary angiography showed no obstructive disease. Transthoracic echocardiogram displayed increased wall thickness, dilated atria and decreased ejection fraction (48%) (figure 1B). Cardiac MRI was performed (figure 1C,D).
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(A) ECG; (B) apical four-chamber transthoracic echocardiogram; (C) cardiac MRI, late gadolinium enhancement image; (D) cardiac MRI, T1 mapping (extracellular volume=54.7%).
Question
Which is the most likely diagnosis of this patient?
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Hypertrophic cardiomyopathy
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Cardiac amyloidosis
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Arrhythmogenic right ventricular cardiomyopathy
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Diffuse subendocardial infarction
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Aortic stenosis
Answer: B
In this report, the patient presented with syncope without cardiac symptoms. Cardiac MRI revealed subendocardial late gadolinium enhancement which led to suspicion of cardiac amyloidosis. Further examinations were performed. Serum protein electrophoresis detected γ M-protein and immunofixation electrophoresis showed IgG λ pattern. Serum-free λ light chains were 166 mg/L, with a κ/λ ratio of 0.174. Bone marrow examination detected 3% immature clonal plasma cells. Finally, this patient underwent an abdominal fat aspiration, and electron microscope confirmed amyloid deposition (figure 2).
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Electron microscope showed amyloid deposition.
Light-chain (AL) amyloidosis is a plasma cell dyscrasia characterised by the pathological production of amyloid fibrils formed by misfolded monoclonal light chains that are deposited in tissues and cause organ dysfunction.1 Syncope could be the first symptom in patients with AL amyloidosis and related to arrhythmia, conduction disturbance or orthostatic hypotension in AL amyloidosis.2
Syncope could be the initial and only symptom in patients with cardiac amyloidosis and is an ominous sign of poor prognosis.2 Careful evaluation is needed for these patients and cardiac MRI can provide valuable clues for the diagnosis.
The other answers are less correct as hypertrophic cardiomyopathy and aortic stenosis would be expected to have high voltage on ECG and would not demonstrate a pattern of diffuse subendocardial late gadolinium enhancement. Diffuse subendocardial infarction and arrhythmogenic cardiomyopathy would not demonstrate diffuse wall thickening or such a markedly elevated extracellular volume on T1 mapping.
Ethics statements
Patient consent for publication
Ethics approval
This study involves human participants and was approved by the Ethics Committee of West China Hospital (2016(335)). Participants gave informed consent to participate in the study before taking part.
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- Source: http://heart.bmj.com/cgi/content/short/110/2/107?rss=1