• Barbara Withers, Georgia McCaughan, Christopher Hayward, Eugene Kotlyar, Andrew Jabbour, Stephen Rainer, Enzo De Angelis, Noemi Horvath, Sam Milliken, Ahmet Dogan, Peter MacDonald, and John Moore.
• Department of Haematology, St Vincent's Hospital, Sydney, New South Wales, Australia.
• Intern Med J. 2022 Jan 1; 52 (1): 69-78.

BackgroundCardiac amyloidosis has a very poor prognosis, but it is the nature of the involved precursor protein that ultimately dictates treatment and survival.AimDefinitively characterise the amyloid subtype by mass spectrometry (MS) in an Australian cohort of patients with cardiac amyloidosis.MethodsWe report the clinical characteristics and survival of 47 cardiac amyloid patients across two Australian centres including 39 patients evaluated for definitive amyloid subtype utilising laser microdissection and tandem mass spectrometry.ResultsA quarter (n = 12) of patients were classified as wild-type transthyretin amyloidosis (ATTRwt), 33 patients as light or heavy chain amyloidosis (AL or AH) and two as hereditary mutant transthyretin amyloidosis. Greater left ventricular hypertrophy (interventricular septum 22 vs 15 mm; P = 0.005) and history of cardiac arrhythmia (75% vs 31%; P = 0.016) were significantly associated with ATTRwt patients compared with AL/AH patients. AL patients demonstrated significantly shorter median survival compared with ATTRwt patients (3.5 vs 37 months; P = 0.007). New York Heart Association class III-IV symptoms or plasma cells ≥10% at diagnosis, were the only independent predictors of worse survival in AL patients on multivariate analysis.ConclusionsAL amyloidosis accounted for 68% of our cohort of patients with cardiac amyloidosis while ATTR accounted for 26%. In the era of novel therapies for both AL amyloid and ATTR, identification of the correct amyloid subtype is essential in making therapeutic decisions and providing accurate prognostic information to patients. Laser microdissection and tandem mass spectrometry plays an important role in identifying amyloid subtype, particularly in complex cases.© 2020 Royal Australasian College of Physicians.

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