Illustrative review of cardiac amyloidosis by multimodality imaging

Cardiac involvement in amyloidosis is characterized by the extracellular deposition of misfolded proteins in the heart with the pathognomonic histological property of green birefringence when viewed under cross-polarized light after staining with Congo red. Although considered a rare disease, recent data suggest that cardiac amyloidosis is underappreciated as a cause of common cardiac diseases or syndromes. The prognosis for transthyretin (TTR) amyloidosis (ATTR) amyloidosis is better than that for amyloid light-chain amyloidosis; however, it is not as good as for other etiologies heart failure. Although there is no proven therapy for patients with ATTR cardiomyopathy (ATTR-CM), tafamidis meglumine, a TTR stabilizer, a study in 2018 found it was associated with reductions in all-cause mortality and cardiovascular-related hospitalizations, as well as with a reduction in the decline in functional capacity and quality of life compared with a placebo for patients with ATTR-CM. As a result of these findings, tafamidis meglumine is currently the only drug approved for patients with both wild-type and variant ATTR-CM, and should be considered for patients whose survival can be reasonably expected. In addition, recent advances in cardiac imaging, diagnostic strategies, and therapies have improved so that interest has been growing in the diagnosis of ATTR-CM by means of non-invasive imaging modalities as a potential means for better management of patients with ATTR-CM. This article reviews the efficacy of non-invasive imaging, especially echocardiography, cardiac magnetic imaging, and ^99mTc-pyrophosphate scintigraphy for diagnosis of cardiac amyloidosis.