Cardiac amyloidosis: A diagnostic challenge

Abstract

Cardiac amyloidosis is indeed a condition characterized by the deposition of amyloid proteins in the myocardium, leading to thickening and stiffening of the heart muscle. These abnormal protein deposits can interfere with the heart's normal functioning and may pose diagnostic challenges due to its varied clinical presentation and resemblance to other heart condition. Here, we present a case of 55-year-old female patient of uncontrolled hypertensions for 15 years. About 15 years ago, she presented with chest pain and was diagnosed with cardiomyopathy (CM) characterized by low left ventricle (LV) function of unknown cause. Despite being on antihypertensive treatment, the patient continued to experience chest heaviness with persistent elevate blood pressure. An echocardiogram revealed increased LV septal wall thickness, valvular thickening, and biatrial dilation. Subsequently, cardiac magnetic resonance imaging (CMR) was performed, which revealed left atrium enlargement and asymmetrical myocardial wall thickening, particularly at the septum. White blood axial image revealed thickened inter atrial septum, while late gadolinium enhancement (LGE) magnetic resonance (LGE MR) images showed patchy LGE at the base relative to the apex of the myocardium, highlighting the base-to-apex gradient, subendocardial pattern enhancement at apical lateral wall, and transmural pattern enhancement of the mid anteroseptal and inferoseptal wall. Additionally, a short axis time to invert T1 scout image of left ventricle displayed an abnormal nulling pattern initially in the myocardium, followed by the blood pool, and finally the spleen. These findings collectively led to the diagnosis of cardiac amyloidosis.

Keywords: Cardiac amyloidosis; Cardiac magnetic resonance (CMR); Late gadolinium enhancement (LGE); Postcontrast invert T1 scout images Abnormal nulling pattern (ANP); Transthyretin amyloid cardiomyopathy (ATTR-CM).

Fig. 1

Echocardiography selected images (A and B) 4-chamber views showing increased LV septal wall thickness (arrow head on [A]), biatrial dilation (thick arrows on [A]), and valvular thickening are shown (arrows on [B]). (C) Pulsed wave Doppler of the mitral inflow: Mitral inflow demonstrates a high E-wave velocity (long arrow) with a small A-wave velocity, E/A >2, and short deceleration time of 100 msec (short arrow).

Fig. 2

4CH (Chamber view) steady state free precession image reveals: (A) left atrium enlargement (small arrow) and asymmetrical myocardial wall thickening particularly at the interventricular septum (arrow), (B) 2 CH (chamber view) steady state free precession image reveals left ventricular thick wall (arrow), trabeculated (star) with preserved cavity volume.

Fig. 3

(A) White blood axial image shows thickened inter atrial septum (arrow), (B) T2 4 chamber view with no evidence of hypersignal intensity of myocardial wall.

Fig. 4

LGE MR image (3 -chamber LV out flow (C), short axis views (A, D) and 4-chamber view (B) show patchy late gadolinium enhancement at the base relative to the apex of the myocardium, highlighting the base-to-apex gradient (arrows). In addition, there is diffuse enhancement of both atrial wall (C large arrows). In many parts. the enhancement is subendocardial, most pronounced on (E) short axis subendocardial pattern enhancement at apical lateral wall, (F) short axis view small focal transmural pattern and additional areas of subendocatdial enhancement of mid anteroseptal and inferoseptal wall.

Fig. 5

Short axis time to invert T1 scout image of left ventricle showing increasing inversion time from (A) to (D) abnormal nulling pattern initially blood pool, myocardium and spleen all bright (A), myocardium null before blood (B) blood pool nulls next (C) and finally spleen (D).