A 59 year old man presents with worsening dyspnea on exertion. He has history of hypertension, atrial fibrillation, and prior echocardiogram demonstrated left ventricle wall thickening and decreased ejection fraction.
He underwent a cardiac MRI:
Delayed enhancement views after administration of IV Gadolinium-based contrast:
Cardiac MR images demonstrate diffuse myocardial thickening most pronounced in the septum and bi-atrial enlargement. There is moderate diffuse hypokinesis.
There is multifocal subendocardial delayed enhancement in the left ventricle. However septal delayed enhancement is nearly transmural, and additional delayed enhancement is seen in the right ventricle free wall.
This is a patient with cardiac amyloidosis. The cardiac MR images demonstrate multiple classic features, with the hallmark being diffuse/multifocal subendocardial delayed enhancement in a nonvascular distribution.
Another prominent feature of cardiac amyloidosis is abnormal suppression/nulling of the myocardium on the TI scout series. With increasing inversion times, the myocardium normally takes longer than blood pool to be nulled. However in this case portions of the myocardium (arrowheads) are nulled before blood pool.
This patient underwent further nuclear medicine imaging after intravenous injection of technetium-99 pyrophosphate (PYP).
While a normal patient would have no myocardial Tc99m-PYP activity, this patient has extensive uptake which is compatible with transthyretin cardiac amyloidosis (also known as ATTR cardiac amyloidosis).
This radiotracer has been shown to be an accurate modality for diagnosing ATTR cardiac amyloidosis and differentiating this from AL cardiac amyloidosis. This is an important distinction provided the treatment and prognosis differences between AL amyloidosis (hematopoietic disorder treated with chemotherapy, median survival <12 months) and ATTR amyloidosis (senile or hereditary buildup of plasma protein, treated with novel agents, median survival 3-5 years). On MRI, transmural delayed enhancement and right ventricle delayed enhancement have been suggested as signs of ATTR amyloidosis.
Patel AR, et al. Role of cardiac magnetic resonance in the diagnosis and prognosis of nonischemic cardiomyopathy. JACC: Cardiovasc Imaging 2017;10:1180-93. Castano A, et al. Multicenter study of planar technetium 99m pyrophosphate cardiac imaging: Predicting survival for patients with ATTR cardiac amyloidosis. JAMA Cardiol 2016;1:880-9. Dungu JN, et al. CMR-based differentiation of AL and ATTR cardiac amyloidosis. JACC: Cardiovasc Imaging 2014;7:133-42.
