Cardiac Amyloidosis Mimicking Non-ST-Segment Myocardial Infarction: A Case Report

Abstract

Cardiac amyloidosis is a rare but increasingly recognized condition characterized by the deposition of amyloid fibrils in cardiac tissue, leading to structural and functional heart impairment. This infiltrative cardiomyopathy often mimics more common cardiac conditions, posing significant diagnostic challenges. Particularly deceptive is its presentation as non-ST-segment elevation myocardial infarction (NSTEMI), where the clinical overlap necessitates considering amyloidosis in differential diagnoses. A 75-year-old male presented with muscle weakness, respiratory infection symptoms, and elevated cardiac enzymes. His history included a recent hospitalization for NSTEMI, with normal coronary angiography. Initial evaluations showed elevated troponin and CRP levels. A comprehensive cardiac assessment revealed a dilated ascending aorta, moderate systolic dysfunction (left ventricular ejection fraction (LV-EF), 47%), and asymmetrical interventricular septal thickening, suggesting hypertrophic cardiomyopathy or amyloidosis. The patient improved and was referred for further specialized care. Cardiac amyloidosis can mimic acute coronary syndrome (ACS), presenting with chest pain and elevated cardiac biomarkers. Differentiation is critical as amyloidosis involves myocardial infiltration by amyloid proteins, leading to restrictive cardiomyopathy. Advanced imaging techniques like cardiac MRI and nuclear scintigraphy are essential for accurate diagnosis and appropriate management, impacting therapeutic strategies and patient outcomes.

Keywords: cardiac amyloidosis; electrocardiography; myocardial infiltration; nstemi; troponin.

Figure 1. Magnetic resonance tomography of the brain

T2-weighted axial scan of the brain: Arrow shows small ischemic lesion in the midbrain

Figure 2. Cardiac magnetic resonance tomography

T2-weighted images axial scan of the heart: Arrow shows hyperintense areas within the myocardium

Figure 3. Cardiac magnetic resonance imaging (MRI) T1 map

The bright orange area in the myocardium suggests prolonged T1 relaxation time (white arrow). The surrounding purple and blue areas represent normal myocardium with shorter T1 relaxation times (yellow arrow)