Clinical and imaging profiling of restrictive cardiomyopathies: insights into amyloid, sarcoid, and iron overload phenotypes.

Restrictive cardiomyopathy is a rare and heterogeneous group of myocardial disorders characterized by increased myocardial stiffness, impaired diastolic filling, and elevated ventricular pressures. Infiltrative diseases are among the most common etiologies of RCM. This review highlights the importance of recognizing characteristic clinical patterns and the role of multimodality imaging in cardiac amyloidosis, cardiac sarcoidosis, and iron overload cardiomyopathy. Heart failure and cardiac arrhythmias are frequent manifestations of these diseases, often resulting in poor prognosis and death if left untreated. Early and accurate diagnosis is crucial for effective management; however, these diseases are often underdiagnosed or misdiagnosed due to overlapping features with other forms of cardiomyopathies, such as hypertrophic cardiomyopathy, hypertensive heart disease, ischemic cardiomyopathy, heart failure with preserved ejection fraction, and other nonischemic cardiomyopathies. With the development of novel therapies that are most effective when initiated early, accurate and prompt diagnosis has become increasingly important to optimize outcomes in these patients. Despite some shared features, each of these conditions has distinct "red flag" clinical characteristics that can raise suspicion for the disease. Advances in multimodality imaging have further improved diagnostic accuracy. Echocardiography can reveal features consistent with restrictive physiology, which is common across all infiltrative diseases, but it has limited ability to differentiate between them. Cardiac magnetic resonance imaging, with detailed tissue characterization, can identify unique and disease-specific characteristics for each of these conditions. Finally, radionuclide imaging can play a pivotal role, not only as a confirmatory test but also in monitoring the response to therapy.