Table 1: Characteristics of transthyretin amyloidosis cardiomyopathy.

Characteristics	Notes
Demographics	ATTRwt: age of onset >65 years ATTRv: age of onset between 30 and 80 years (dependant on the mutation) Male predominance
Prevalence	True prevalence is unknown: In autopsy studies, ATTR deposits have been demonstrated in 25% of myocardial samples in elderly patients p.(Val142Ile) variant is carried by 3-4% of African Americans p.(Thr80Ala) variant is carried by ~1% of Irish descentp. (Val50Met) variant is carried by ~0.1% in endemic areas of Portugal, Sweden and Japan
Cardiac manifestations	Restrictive cardiomyopathy Systolic and diastolic dysfunction Atrial fibrillation Aortic stenosis Conduction disease
Extra-cardiac manifestations	Carpal tunnel syndrome Biceps tendon rupture Lumbar spine stenosis Peripheral/autonomic neuropathy in patients with ATTRv and a mixed phenotype
Serum cardiac enzymes	Elevated N-terminal pro B-type natriuretic peptide Elevated troponin
Electrocardiographic findings	Small voltage QRS complexes Pseudo infarct pattern Ischaemic or non-specific T-wave abnormalities Left anterior hemiblock Heart block
Echocardiographic findings	Increased biventricular wall thickness Increased relative wall thickness Small left ventricular cavity Elevated left ventricular filling pressures (increased E/A ratio and E/e’) Reduced mitral and tricuspid annular systolic plane excursion Bull's eye strain pattern with apical sparing
Cardiac magnetic resonance findings	Increased left ventricular mass Increased native T1 Diffuse subendocardial/transmural late gadolinium enhancement Increased extracellular volume
Bone scintigraphy	Grade 2 or 3 cardiac uptake in the majority of cases*
Diagnosis	The presence of heart failure symptoms, and characteristic features of cardiac amyloidosis on echocardiography or CMR imaging and one of the following: Direct endomyocardial biopsy proof of ATTR deposits Cardiac uptake on bone scintigraphy and non-cardiac histology demonstrating ATTR deposits Non-biopsy criteria: grade 2-3 cardiac uptake on bone scintigraphy and the absence of a biochemical evidence of a plasma cell dyscrasia in the plasma or urine

*Certain forms of ATTRv-CM produce disproportionately low cardiac uptake on bone scintigraphy such as p.(Ser97Tyr), p.(Phe84Leu) and p.(Tyr134Cys).

ATTR = transthyretin amyloidosis; CMR = cardiac magnetic resonance; v = variant; wt = wild type.