Diagnostic imaging of cardiac amyloidosis

Systemic amyloidosis encompasses a debilitating, under-diagnosed but increasingly recognized group of disorders characterized by the extracellular deposition of misfolded proteins in one or more organs. Cardiac amyloid deposition leads to an infiltrative or restrictive cardiomyopathy and is the major contributor to poor prognosis in patients with systemic amyloidosis. In total, >30 proteins can form amyloid fibrils, but the two main types of amyloid that can infiltrate the heart are monoclonal immunoglobulin light-chain amyloid and transthyretin amyloid. Cardiac amyloidosis can be acquired in older individuals or inherited from birth. Given the nonspecific symptoms of these disorders, a high index of suspicion is paramount in making the correct diagnosis, which can involve the use of non-invasive imaging methods such as echocardiography, bone scintigraphy and cardiovascular MRI. In the past decade, the use of cardiovascular MRI with tissue characterization and bone scintigraphy to diagnose cardiac amyloidosis has revolutionized our understanding of the disease, leading to changes in patient care. However, a need remains for improved awareness and expertise, and greater clinical suspicion, because the initial clues provided by electrocardiography and echocardiography might not be typical. With specific treatments now available, timely diagnosis of cardiac amyloidosis is more important than ever. In this Review, we discuss the current and novel approaches for the diagnostic imaging of cardiac amyloidosis.