The role of echocardiography and 99mTc-HDP scintigraphy in non-invasive diagnosis of cardiac amyloidosis

RATIONALE: Cardiac amyloidosis, considered for the last years to be a rare disease, is one of the determinants of HFpEF. The non-specific clinical presentation and the difficulties related to endomyocardial biopsy have made cardiac amyloidosis an underdiagnosed clinical entity. Improvement of non-invasive diagnostic techniques and the development of new therapies increased clinical awareness for this form of restrictive cardiomyopathy. We here summarize echocardiography and Tc-HDP scintigraphy findings in 6 cases of cardiac amyloidosis and review the literature data of this progressive and fatal cardiomyopathy. PATIENTS CONCERNS: The main clinical manifestations were fatigue, low exercise tolerance and edemas. The right heart failure symptoms usually dominated the clinical picture. DIAGNOSES: All cases were evaluated by echocardiography; 3 cases were further examined by bone scintigraphy and 4 cases a peripheral biopsy was performed. Electrocardiography showed low-voltage QRS complexes and "pseudo-infarct" pattern in the precordial leads, contrary to the echocardiographic aspect, which revealed thickening of ventricle walls. Biatrial dilation and diastolic disfunction were observed. Impaired systolic function was detected in advanced stages of the disease. Tc-HDP scintigraphy revealed cardiac uptake of radiopharmaceutical and managed to confirm the diagnosis in 1 case of cardiac amyloidosis in which salivary gland biopsy was negative. INTERVENTIONS: The treatment was based on managing fluid balance, with the mainstream therapy represented by diuretics. Neurohormonal agents, usually used in heart failure treatment were avoided, due to poor tolerance and worsening of disease course. The management of these 6 cases was challenging due to the refractory manifestation of congestive heart failure. OUTCOMES: During follow-up, 4 of the 6 patients from the current study died in the first year after the final diagnosis was established. LESSONS: Nuclear imaging of cardiac amyloidosis has a revolutionary development nowadays. Bone scintigraphy presents promising results for identifying patients at early stages of disease and to differentiate between cardiac amyloidosis types. Further studies are necessary for the standardization of imaging protocol and development of non-invasive diagnostic tools, especially in assessing the response to treatment and disease progression, for which little is known.