Pretty Little Layers: A Case of Multifactorial Subendocardial Disease (QF_TH_067)

An 85-year-old male presented with mild progressive dyspnea during frequent physical activity. His past medical history was significant for atrial fibrillation with tachy-brady syndrome status post pacemaker implantation and medically treated coronary disease on metoprolol, aspirin, and apixaban. In the setting of his symptoms, a transthoracic echocardiogram was performed, which showed a newly reduced left ventricular ejection fraction (40%), regional wall motion abnormalities, and septal thickening (18 mm). 

Diagnostic Techniques and Their Most Important Findings:

A cardiac MRI was performed to assess myocardial viability in the setting of his chronic coronary artery disease. This confirmed moderately reduced left ventricular systolic function (LVEF 36%), as well as myocardial thinning and akinesis, with associated fatty metaplasia (figure A) and near transmural late enhancement of the basal-to-mid inferior and lateral walls and papillary muscles (figure B), consistent with a predominately nonviable myocardial infarction.   

Due to worsening symptoms, the patient sought a second opinion. Repeat assessment of the outside cardiac MRI revealed additional subtle diffuse subendocardial enhancement of the left ventricular and right ventricular myocardium (figure B). Parametric mapping revealed elevated native T1 (1215 ms) and extracellular volume (42%) in the severely thickened septum (22 mm), providing additional evidence for concomitant cardiac amyloidosis. Monoclonal protein and free light chain analyses were normal.  Technetium-pyrophosphate scintigraphy showed grade 3 myocardial uptake on planar and SPECT imaging (figure 3).  Genetic testing confirmed the absence of a TTR gene mutation, and the patient was initiated on tafamidis for wild-type ATTR cardiac amyloidosis. 


Learning Points from this Case: This case illustrates the complexity of diagnosing multifactorial subendocardial disease and highlights the value of comprehensive cardiac MRI. Cardiac amyloidosis causes diffuse myocardial infiltration and typically presents with concentric wall thickening, diffuse subendocardial enhancement, and preserved ejection fraction. However, up to one-third of cardiac amyloidosis patients may present with a reduced ejection fraction due to advanced disease or comorbidities. This case underscores the importance of maintaining a high degree of suspicion for infiltrative diseases in patients with hypertrophic remodeling that appears disproportionate to chronic myocardial infarction.