Clinical History An 87-year-old man with a history of coronary artery disease and previous coronary artery bypass graft (CABG) surgery was admitted to Mass General with congestive heart failure. A TTE (transthoracic echocardiogram) revealed moderate left ventricular systolic dysfunction and severe aortic stenosis. TTE also revealed a restrictive filling pattern in diastole, suggestive of an infiltrative myopathy. Prior to proceeding with high-risk repeat cardiac surgery, a cardiac MRI (CMR) was requested to further explore the possibility of infiltrative disease.
Findings TTE revealed moderate concentric left ventricular (LV) hypertrophy with normal left ventricular chamber dimensions (Figure 1). The LV myocardium demonstrated increased reflectivity, suggestive of an infiltrative cardiomyopathy, and the transmitral Doppler filling pattern was "restrictive," suggestive of elevated left-atrium filling pressures and/or a non-compliant LV. The estimated left ventricular ejection fraction (LVEF) was 38%. Non-specific thickening of both anterior and posterior mitral leaflets was noted, together with marked biatrial enlargement.
CMR (Figures 2 and 3) demonstrated diffuse sub-endocardial abnormal delayed enhancement involving all coronary artery territories, with relative sparing of only small portions of the mid-inferior and septal wall. The resting LVEF was confirmed to be significantly impaired at 33%. The overall findings were consistent with diffuse amyloid infiltration of the myocardium.
(Click on image to enlarge)
Figure 1:The left ventricular cavity size is normal. The left ventricular systolic function is impaired. There is significant left ventricular hypertrophy. The LV is echo bright and suggestive of an infiltrative cardiomyopathy.
Figure 2,3:Paraseptal long axis (2) and short axis (3) cardiac MRI demonstrates diffuse subendocardial abnormal delayed enhancement involving all coronary artery territories and nearly the entire left ventricle with relative sparing of only small portions of the mid inferior and septal wall.
Discussion Amyloidosis is a common cause of restrictive cardiomyopathy in octogenarians. It arises due to deposition of proteinaceous material in the interstitium, leading to atrophy of myocardium. The classic imaging appearance includes concentric wall thickening, reduced ejection fraction, and biatrial enlargement 1-3. CMR findings include global or sub-endocardial delayed gadolinium enhancement, with heterogeneous patchy enhancement in the myocardium. The prognosis for patients with amyloidosis is poor, with senile amyloidosis being a more favourable subtype. In our patient, a myocardial biopsy confirmed the diagnosis of cardiac amyloidosis, and surgery was deferred. The characteristic delayed enhancement pattern makes MR a valuable imaging modality in the workup of amyloidosis.
Wood MJ and Picard MH. Utility of echocardiography in the evaluation of individuals with cardiomyopathy. Heart, 2004; 90: 707-712