Cardiac Amyloidosis

Caused by deposition of misfolded precursor proteins as fibrillary amyloid deposits in cardiac tissues. The two primary subtypes of systemic amyloidosis causing cardiac involvement are immunoglobulin light chain (AL), a plasma cell dyscrasia, and transthyretin (ATTR).

Clinical Manifestations

Both have a similar phenotype, notable for increased left ventricular (LV) wall thickness and an ability to disguise itself clinically as common cardiovascular disease states, including HF, atrial arrhythmias, and aortic stenosis (AS).

AL Amyloidosis

ATTR Amyloidosis

Diagnostic Workup for Cardiac Amyloidosis

Consider diagnostic workup for cardiac amyloidosis for patients with HF who have 1+ of the following (Strong Recommendation, Moderate-Quality Evidence)

• Unexplained increased LV wall thickness
• Age > 60 with low-flow low-gradient AS and LVEF > 40%
• Unexplained peripheral sensorimotor neuropathy and/or dysautonomia
• History of bilateral carpal tunnel syndrome
• Established AL or ATTR amyloidosis

Lab Investigations

1. Troponin: chronically elevated, AL > ATTR due to myotoxic effect of light chains. Has prognostic value.
2. NT-proBNP: chronically elevated, elevated out of proportion of degree of clinical HF.
3. Amyloid labs: SPEP and UPEP with immunofixation, sFLC. Indicated in all suspected cases.

Imaging

1. Echocardiogram: incr RV/LV thickness, preserved ventricular size, BiAE, diastolic dysfunction, increased valvular and IAS thickness, small PCE, and reduced LV GLS with preserved apical strain
2. Cardiac MR: diffuse trasmural or subendocardial pattern of LGE, etc
3. Pyrophosphate nuclear scintigraphy: perform this if AL amyloid is ruled out and ATTR cardiac amyloidosis is suspected

Management of Cardiac Amyloidosis