Case report: recurrent chest pain as initial manifestation of rapidly progressing light-chain cardiac amyloidosis with microvascular infiltration-a novel red flag associated with poor outcomes

Abstract

Background: Angina due to microvascular amyloid infiltration is an under-recognized early red flag of infiltrative disease and should be investigated as a predictor of poor outcomes.

Case summary: A 73-year-old man with cardiovascular risk factors and a history of treated obstructive coronary artery disease presented 10 months later with recurrent angina. His condition progressively worsened, with the development of severe dyspnoea. Within 6 months, he succumbed to cardiogenic shock in the presence of severe biventricular dysfunction and unobstructed coronary arteries. Post-mortem diagnosis revealed AL cardiac amyloidosis with massive myocardial infiltration and extensive microvascular amyloid deposits.

Discussion: This case underscores chest pain as a critical clinical marker, potentially indicating microvascular amyloid infiltration in patients with light-chain cardiac amyloidosis, particularly those with unobstructed coronary arteries. Its assessment may also have implications for future therapies.

Keywords: Amyloidosis; Case report; Fatal cardiac amyloidosis; Microvascular dysfunction; Microvascular infiltration; Recurrent angina.

Figure 1

Series of electrocardiograms demonstrating dynamic changes during the disease course. The peripheral leads from February 2023 demonstrated left atrial enlargement, left ventricular hypertrophy, and residual subepicardial ischaemia in the inferior leads. In December 2023, the emergence of new lateral repolarization abnormalities is discernible, accompanied by a less conspicuous decline in peripheral voltages. From April 2024, it can be observed that there is fragmentation in lead aVL and a marked progressive reduction of peripheral voltages, to the extent that in June 2024, the QRS complexes are difficult to discern (<0.5 mV). The precordial leads demonstrate a progressive evolution of anterior pseudonecrosis, commencing in April 2024 and accompanied by the persistence of lateral negative T waves.

Figure 2

Change in key echocardiographic parameters over time. Echocardiographic findings. In February 2023, the patient was discharged with normal biventricular function and Grade 2 diastolic dysfunction. The well-known evolution of AL-CA is severe hypertrophy, which can lead to heart failure with preserved ejection fraction. However, in this case, the restrictive filling pattern was associated with severe biventricular dysfunction.

Figure 3

On the left, gross evaluation of unfixed heart following longitudinal dissection. Diffuse increase in wall thickness in both ventricles, in the interventricular septum involving the subvalvular aortic region, extending to the papillary muscles, atrioventricular valves, the interatrial septum, and both atria. Overall heart weight was 620 g. The heart exhibits a heterogeneous colour with pale areas and a faint yellowish tone, suggesting myocardial ischaemia. On the right, histological evaluation of myocardial samples. (A) Haematoxylin and eosin staining, original magnification 40×: a substantial interstitial infiltration is evident in the myocardial tissue, resulting in disruption of the myocardial structure and marked capillary rarefaction. (B) Congo red staining under polarized light microscopy, original magnification 100×: the image demonstrates the presence of relevant microvascular cardiac infiltration, which has resulted in critical stenosis of a small arteriole. The sample demonstrated evidence of secondary myocardial ischaemia. Additionally, amyloid deposits were observed in the pulmonary, hepatic, splenic, and renal micro- and medium-sized arteries.