Potential use of cardiac magnetic resonance imaging in differential diagnosis of cardiomyopathies due to light-chain amyloidosis and transthyretin amyloidosis

BACKGROUND: Cardiac amyloidosis is a serious progressive disease with a high mortality rate. The differential diagnosis of cardiomyopathies due to amyloid light-chain (AL) amyloidosis and transthyretin (ATTR) amyloidosis is important for selecting the optimal treatment strategy. AIM: The aim of this study was to evaluate the capabilities of cardiac magnetic resonance imaging in the differential diagnosis of cardiomyopathies due to AL and ATTR amyloidosis. MATERIALS AND METHODS: A retrospective analysis of the medical records of 25 patients with a confirmed diagnosis of amyloid cardiomyopathy was performed. Patients were divided into two groups according to the type of amyloidosis, with group 1 including patients with cardiomyopathy due to AL amyloidosis and group 2 including patients with cardiomyopathy due to ATTR amyloidosis. All patients underwent contrast-enhanced cardiac magnetic resonance imaging. Volumetric and linear cardiac parameters, ventricular function, and late gadolinium enhancement patterns were assessed. Standard statistical methods were used, and differences were considered significant at p 0.05. RESULTS: Group 2 showed a more significant thickening of the myocardial walls compared to group 1 (interventricular septum: 18 [17; 18] vs. 14.5 mm [12.8; 16.0], p 0.01, posterior wall of the left ventricle: 14 [13; 17] vs. 10.5 mm [10; 12.3], p 0.01). The indexed mass of the left ventricle myocardium was 110 [92; 125] in group 2 and 85 mm [69.3; 91.8] in group 1 (p 0.01). In group 2, late gadolinium enhancement with a transmural left ventricle pattern was more frequently observed in the basal and mid-lower-lateral segments, whereas in group 1, a subendocardial pattern of late gadolinium enhancement was more frequent in the mid-anterior and lower-lateral segments (p 0.05). In addition, frequency of simultaneous contrast enhancement in the subendocardial layers of the interventricular septum on the left ventricle and right ventricle sides was higher in group 2 (100% of cases vs. 50%, p 0.01). Late gadolinium enhancement of the right ventricle was also more common in group 2 (100 vs. 58%, p 0.05), especially in the interventricular septum and inferior wall area (p 0.05). Semi-quantitative assessment of LGE using the Query Amyloid Late Enhancement (QALE) showed greater contrast enhancement in group 2: 13 [12; 14] vs. 10.5 [1.75; 12], p 0.01), and a score greater than 13 differentiated between cardiomyopathy due to AL amyloidosis and ATTR amyloidosis with a sensitivity of 69% and a specificity of 83%. CONCLUSIONS: Cardiac MRI identifies typical features of cardiomyopathies due to AL amyloidosis and ATTR amyloidosis for their differential diagnosis. Further research is needed to confirm diagnostic accuracy of the patterns identified.