P1707 Strain imaging - resolving the diagnostic conundrum of cardiac amyloidosis

Abstract

Abstract Introduction Cardiac amyloidosis is a common cardiac condition and is still significantly underdiagnosed. Autopsy studies revealed that myocardial tranthyretin amyloid deposition is found in up to 30% of patients with HFpEF (heart failure with preserved ejection fraction). A study in 2015 reported that 13% of patients hospitalised due to HFpEF (older than 60 years old and with left ventricular hypertrophy - LVH) had moderate to severe uptake on the Technetium DPD scintigraphy. Strain imaging through Echocardiography can be a useful diagnostic tool and can provide valuable clues towards the aetiology of LVH. Relative "apical sparing" pattern of longitudinal strain has been reported to have good sensitivity and specificity in differentiating patients with cardiac amyloidosis from controls. Case A 66 year old man presented with progressive breathlessness and peripheral oedema. His past medical history included peripheral neuropathy, bilateral decompression procedures for carpal tunnel syndrome and IgM Monoclonal Gammopathy of Undetermined Significance (MGUS). His B-type natriuretic peptide levels were elevated and his ECG showed normal sinus rhythm, RsR" pattern on the anterior leads and no evidence of LVH. The transthoracic echocardiogram showed moderate concentric LVH, normal left ventricular systolic function and mildly impaired left ventricular diastolic function. No evidence of pericardial effusion. Urine protein:creatinine ratio findings were consistent with nephrotic range proteinuria. He had a cardiac MRI that confirmed normal biventricular wall motion and systolic function and a moderate increase in the wall thickness of both ventricles, but showed no evidence of late gadolinium enhancement. At this point, we repeated his transthoracic echocardiogram with the use of strain imaging and it revealed a pattern of apical sparing suggestive of cardiac amyloidosis. After collaboration with the Haematology team, a bone marrow biopsy was performed that showed that the MGUS had progressed to IgM multiple myeloma. There was however no evidence of amyloid deposits. He was subsequently referred to the national amyloidosis centre (as per family request), where a SAP (serum amyloid P) scan showed renal and splenic amyloid deposits confirming Light-chain Amyloidosis. To exclude the possibility of TTR Amyloidosis, he also had a 99mTc-DPD scintigraphy which did not detect any amyloid deposits. He was treated under the care of the Haematology team with Velcade/Cyclophosphamide/Dexamethasone chemotherapy. Conclusion In patients with a clinical suspicion of cardiac amyloidosis, Echocardiography with strain imaging can be very useful and should be performed routinely. Furthermore, in patients with high clinical suspicion of cardiac amyloidosis, diagnostic investigations should persist even if the initial workup does not yield specific findings. Abstract P1707 Figure. Strain imaging findings