Challenging features of left ventricular wall thickening in a young patient with multiple myeloma and shock: when magnetic resonance imaging makes the difference-a case report.

Background: Left ventricular walls may thicken for various reasons in patients with multiple myeloma, and identifying the cause is crucial for targeted treatment, especially in the context of cardiogenic shock. While echocardiography may not provide a definitive diagnosis, cardiac magnetic resonance imaging (MRI), which allows for specific characterization of structural changes in the myocardium, can be diagnostic. Case summary: A 44-year-old Caucasian man with multiple myeloma, recently undergone autologous stem cell transplantation with following medullary aplasia, developed cardiogenic shock. The identification of the underlying cause was challenging since echocardiographic imaging, showing severe thickening of left ventricle walls, was not able to discriminate between coexisting amyloid light-chain (AL) amyloidosis and myocarditis features. Conversely, cardiac MRI imaging played a major role in diagnosing myocarditis. Endomyocardial biopsy was not performed due to severe thrombocytopenia and increased bleeding risk. After initial circulatory support and empiric treatment, the patient ultimately experienced progressive myocardial recovery. Discussion: In patients with multiple myeloma and shock, acute myocarditis and AL cardiac amyloidosis can show similar echocardiographic features yet demand different treatments and lead to varying outcomes. Cardiac MRI plays a crucial role in the diagnostic workup, offering detailed insights that guide targeted management.