Table 1.

Diagnostic Criteria for Cardiac Amyloidosis (Dorbala, 2019)

Diagnostic Criteria	Subtype
Histology of Endomyocardial biopsy
1.   Endomyocardial biopsy showing birefringent amyloid deposition in apple green to polarized light in Congo red. Immunohistochemistry and/or mass spectrometry may be preferred for subtyping.	AL, ATTR, other subtype
Histology of Extracardiac biopsy
1.   The following conditions should be sought in the diagnosis of ATTR amyloidosis: a)   Demonstration of ATTR amyloidosis on extracardiac biopsy, and b)  Presence of typical cardiac imaging features described below	ATTR
2.   The following conditions should be sought for the diagnosis of AL amyloidosis: a)   Demonstration of AL amyloidosis on extracardiac biopsy, and b)  Presence of typical cardiac imaging features described below c)   Abnormality of age-adjusted NT pro BNP or abnormal Troponin T/I/HS Troponin levels; after exclusion of all causes to explain the abnormality of these markers	AL
Clinical Diagnosis of ATTR Cardiac Amyloidosis: 99m Tc-PYP/DPD/HMDP
3.   The diagnosis of ATTR amyloidosis can be made in the presence of the following conditions: a)   Presence of Grade 2 or 3 myocardial involvement in 99m Tc-PYP/DPD/HMDP, and b)  Demonstration of clonal plasma cell absence by serum FLCs and serum and urine immunofixation, and c)   Presence of typical cardiac imaging features described below	ATTR
Typical Imaging Features in the Diagnosis of Cardiac Amyloidosis
Typical cardiac echocardiography or CMR or PET features: All other diseases (including hypertension) that may produce the following imaging findings should be excluded
1.   Echocardiography •     Left ventricular wall thickness >12mm •     Relative apical preservation of global LS ratio (apical LS mean/combined mean+basal LS >1 mean) •     ≥ Grade 2 diastolic dysfunction	ATTR/AL
2.   Cardiac MRI a)   LV wall thickness above the upper limit of normal for gender in unstable condition b)  Overall ECV >0.40 c)   Diffuse late gadolinium increase d)  Abnormal gadolinium kinetics typical for amyloidosis, resetting myocardium before blood pool reset	ATTR/AL
3. PET: 18F-florbetapir or 18F-florbetaben PET a)   Target - background (LV myocardium - blood pool) ratio >1.5 b)  b. Retention index >0.030 min-1	ATTR/AL