CONGRESS ABSTRACT

A 72-year-old male, with a medical history of hypertension, remote bilateral carpal tunnel syndrome and smoldering IgG kappa multiple myeloma (MM), was referred for evaluation of suspected cardiac amyloidosis (CA) due to mild exertional intolerance. Electrocardiogram revealed sinus rhythm, left-axis deviation, low voltage QRS. A transthoracic echocardiogram revealed reduced left ventricular systolic function (ejection fraction of 40%), but the acoustic window was suboptimal. Therefore, a cardiac magnetic resonance was performed, which revealed moderate basal septal hypertrophy (13 mm), transmural late-enhancement in the lateral and inferior wall of the left ventricle and in the atrial walls, with a left ventricular ejection fraction of 36%. On laboratory evaluation high-sensitivity troponin I was normal (18 ng/L), N-terminal pro-B-type natriuretic peptide was mildly elevated (509 pg/ml). The presence of MM and imaging findings of CA led to high suspicion of AL-CA. A fat pad aspirated was negative for amyloid deposition. Radionuclide imaging showed grade 1 cardiac uptake. At that point, an endomyocardial biopsy was required, since CA was highly suspected in the presence of plasma cell dyscrasia: the endomyocardial biopsy was Congo red positive, and the immunoelectron microscopy was positive for transthyretin (TTR) amyloid deposition. TTR gene analysis did not reveal any pathogenic mutation. Taken together, these findings confirmed wild-type TTR-CA in a patient with concurrent smoldering multiple myeloma. The patient was referred to Padua cardiological clinic: given the limited burden of symptoms, the low level of cardiac biomarkers and the low grade of Perugini's score, it was decided a "wait and see" approach and a close clinical follow-up with a nuclear bone scintigraphy scan at 6 months. This case highlights several important teaching points: 1) TTR-CA can present with concomitant MM and should be on the list of differential diagnoses along with AL-CA when amyloid cardiomyopathy is suspected; 2) endomyocardial biopsy is required to make the diagnosis of TTR-CA for cases of suspected CA with plasma cell dyscrasia; 3) diagnosis of TTR-CA in MM patients is crucial to ensure appropriate treatment targeting TTR-CA. In addition, this case underscores the importance of a multidisciplinary approach, integrating hematology, pathology and cardiology expertise, to ensure accurate diagnosis and optimal management in this complex patient population.