Abstract
Background: Diagnosis of cardiac involvement in amyloid A (AA) amyloidosis is challenging since AA amyloidosis is a rare disease and cardiac involvement even less frequent. The diagnostic yield of currently available non-invasive imaging methods is not well-studied and rather limited, and invasive endomyocardial biopsy (EMB) is rarely performed due to the potential risk of this procedure. Cardiovascular magnetic resonance (CMR)-based myocardial tissue characterization by late-gadolinium-enhancement (LGE) imaging and novel-mapping approaches may increase the diagnostic yield in AA amyloidosis.Methods: Two patients with AA amyloidosis in whom cardiac involvement was suspected based on CMR findings and subsequently proven by biopsy work-up are presented. CMR studies were performed on a 1.5-T system and comprised a cine steady-state free precession pulse sequence for ventricular function and a late-gadolinium-enhancement (LGE) sequence for detection of myocardial pathology. Moreover, a modified Look-Locker inversion recovery (MOLLI) T1-mapping sequence was applied in basal, mid and apical short-axes prior to contrast agent administration and ~20 min thereafter to determine native T1 and ECV values.Results: Both patients showed slightly dilated left ventricles (LV) with mild to moderate LV hypertrophy and preserved systolic function. Only a very subtle pattern of LGE was observed in both patients with AA amyloidosis. However, markedly elevated native T1 (max. 1,108 and 1,112 ms, respectively) and extracellular volume fraction (ECV) values (max. 39 and 48%, respectively) were measured in the myocardium suggesting the presence of cardiac involvement - with subsequent EMB-based proof of AA amyloidosis.Conclusion: We recommend a multi-parametric CMR approach in patients with AA amyloidosis comprising both LGE-based contrast-imaging and T1-mapping-based ECV measurement of the myocardium for non-invasive work-up of suspected cardiac involvement. The respective CMR findings may be used as gatekeeper for additional invasive procedures (such as EMB) and as a non-invasive monitoring tool regarding assessment and modification of ongoing treatments.
Highlights
Amyloidosis is a family of multifaceted, heterogenous diseases based on abnormally folded proteins characterized by pathological accumulation of insoluble, polymeric protein fibrils in the extracellular space of various tissues and organs— sometimes leading to organ dysfunction, organ failure, and death
Secondary or amyloid A (AA) amyloidosis is caused by overproduction and accumulation of the acute-phase protein “serum amyloid A” (SAA) that can be highly expressed in patients with chronic inflammation, cancers orinflammatory diseases [4]
The incidence of AA amyloidosis, in particular in developed countries, is low since this disorder only occurs as a long-term complication of rather severe chronic inflammatory disorders that in turn are mostly wellmanaged in developed countries—in case of timely detection
Summary
Amyloidosis is a family of multifaceted, heterogenous diseases based on abnormally folded proteins characterized by pathological accumulation of insoluble, polymeric protein fibrils in the extracellular space of various tissues and organs— sometimes leading to organ dysfunction, organ failure, and death. There are more than 30 different proteins, which have been identified as amyloidogenic—out of which at least 17 can cause systemic disease [1]. Secondary or amyloid A (AA) amyloidosis is caused by overproduction and accumulation of the acute-phase protein “serum amyloid A” (SAA) that can be highly expressed in patients with chronic inflammation, cancers or (auto)inflammatory diseases [4]. To identify the underlying inflammatory process in newly diagnosed AA amyloidosis, several factors ranging from genetic variation to ancestral history of patients have to be taken into consideration. Cardiovascular magnetic resonance (CMR)-based myocardial tissue characterization by late-gadolinium-enhancement (LGE) imaging and novel-mapping approaches may increase the diagnostic yield in AA amyloidosis
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