Diagnostics of cardiac amyloidosis

Abstract

The early diagnosis of cardiac amyloidosis is decisive for the success of treatment of affected persons. The thorough clinical investigation of the patient should be followed by appropriate diagnostics using modern procedures. The main symptoms are dyspnea, loss of performance and edema and in later stages cardiac arrhythmias in the form of atrioventricular conduction disturbances and atrial fibrillation but ventricular arrhythmias occur more rarely. During heart failure due to cardiac amyloidosis an increase of cardiac enzymes frequently occurs (e.g., creatine kinase, troponin, N‑terminal pro-brain natriuretic peptide), which can be included in the risk stratification and treatment monitoring, taking certain limitations into consideration. The investigation of light chains in serum and/or urine should be carried out immediately, as soon as there is a clinical and echocardiographic suspicion of cardiac amyloidosis. Subsequently, either cardiac magnetic resonance imaging (MRI) or bone scintigraphy should be carried out, depending on the locally available options. Depending on the results of these two imaging procedures, a decision must be made as to whether further diagnostic steps (e.g., endomyocardial biopsy) are necessary. In the last decade bone scintigraphy has proven to be a blessing for the diagnostics of cardiac amyloidosis but many partial aspects and limitations necessitate special and careful consideration. A Perugini score of 2 or 3 is initially "indicative" of cardiac amyloidosis but not yet "confirmative" for a specific subtype. Only after an additional negative result of the light chain determination, can the diagnosis of ATTR amyloidosis be noninvasively made. Cardiac amyloidosis shows a particularly characteristic contrast enhancement in cardiac MRI, which mostly begins in the inner (subendocardial) layers of the basal left ventricular (LV) wall and frequently appears to be circular in the cross-sectional view of the left ventricle. Supplementary T1 and extracellular volume fraction mapping results, which are shown as color-coded maps, enable the rapid and elegant assessment of the myocardial structure and the extent of amyloid deposition. An additional investigation of the TTR gene is recommended in the case of ATTR amyloidosis for a differentiation between hereditary and acquired ATTR, as from this, further therapeutic consequences can be derived.