Multi-modality imaging of cardiac amyloidosis: Contemporary update

Table 4 Contemporary diagnostic criteria for cardiac amyloidosis, modified from expert consensus recommendations[61]

Category	Criteria
Endomyocardial biopsy	Apple-green birefringence with Congo red staining and polarized light, immunohistochemistry and/or mass spectrometry typing confirmed
Extracardiac biopsy	ATTR: Biopsy proven and typical imaging findings
	AL: biopsy proven and typical imaging features or abnormal cardiac biomarkers (N-terminus B-type natriuretic peptide or troponins if other causes excluded)
Non-biopsy (or ATTR)	Grade 2 or 3 myocardial uptake of radiotracer
	Serum free light chains, serum and urine immune-fixation not finding clonal plasma cell process
	Typical imaging findings
Typical imaging findings: echocardiography	Left ventricular wall thickness > 12mm
	Relative apical sparing of left ventricular longitudinal strain ratio (apical average/basal and mid average > 1)
	Grade 2 or higher diastolic dysfunction
Typical imaging findings: magnetic resonance imaging	Left ventricular wall thickness > upper limit normal for sex
	Global extracellular volume > 0.40
	Abnormal gadolinium kinetics, myocardial nulling prior to blood pool nulling or difficulty in nulling the myocardium because of diffuse amyloid infiltration
	Diffuse, subendocardial or patchy late gadolinium enhancement patterns may be observed
Typical imaging findings: Positron emission tomography	18F-florbetapir or 18F-florbetabem
	Left ventricular myocardium to blood pool ratio > 1.5
	Retention index > 0.030/min

ATTR: Transthyretin amyloidosis; AL: Light chain amyloidosis.