Avoiding misdiagnosis: expert consensus recommendations for the suspicion and diagnosis of transthyretin amyloidosis for the general practitioner

Table 3 Clinical Tests and Findings Potentially Suggestive of ATTR Amyloidosis

Heart
ECG	Normal or low ECG voltage^a often discrepant from ECHO findings, pseudo-infarct pattern, atrioventricular block, bundle branch block
ECHO	Increased left and/or right ventricular wall thickness, increased atrial septal thickness, impaired longitudinal strain, apical sparing pattern by longitudinal strain, thickened valve leaflets, increased LV filling pressures, pericardial effusion
CMR	Increased biventricular wall thickness, increased LV mass, diffuse subendocardial or transmural late gadolinium enhancement, increased native noncontrast T1 and ECV
^99mTc bone scintigraphy (DPD/PYP/HMDP)	Grade 2/3 myocardial uptake; note, this test should always be ordered with serum FLC/serum and urine immunofixation electrophoresis to rule out the presence of a monoclonal protein. If any of these are abnormal, endomyocardial biopsy with typing of amyloid fibril may be necessary for an accurate diagnosis
Serum cardiac biomarkers	Increased BNP or NT-proBNP levels, increased troponin T or troponin I levels
Peripheral nerves
Nerve conduction study	Axonal sensorimotor neuropathy, CTS
Neuro MRI	Swelling of dorsal ganglia
Autonomic nerves
Schellong test	Neurologic orthostatic hypotension
CVRR	Decreased CVRR
Sweat test Laser Doppler flowmetry	Anhidrosis, hypohidrosis

ATTR Transthyretin amyloid, ATTRwt Wild-type transthyretin amyloidosis, BNP Brain natriuretic peptide, CMR Cardiovascular magnetic resonance, CT Computed tomography, CTS Carpal tunnel syndrome, CVRR Coefficient of variation in electrocardiographic R-R interval variability, DPD 3,3-diphosphono-1,2-propanodicarboxylic acid, ECG Electrocardiography, ECHO Echocardiography, ECV Extracellular volume, FLC Free light chain, HMDP Hydroxymethylene diphosphonate, LV Left ventricular, LVWT Left ventricular wall thickness, MR Magnetic resonance, MRI Magnetic resonance imaging, NT-proBNP N-terminal probrain natriuretic peptide, PYP Pyrophosphate, TTR Transthyretin
^aCriteria for low voltage is present in only 25% of patients with ATTRwt; most patients, however, will have a low “voltage to mass” ratio

ISSN: 2731-4553