Abstract Body (Do not enter title and authors here): Background: Amyloidosis occurs when endogenous circulating proteins misfold and are deposited in various tissues, including the myocardium. Apolipoprotein A-IV (Apo-AIV) amyloidosis is a rare form of this condition caused by deposition of amyloid proteins in the heart, kidney, and duodenum.
Case Presentation: A 78-year-old male patient with coronary artery disease and prior ST elevation myocardial infarction, prior two vessel coronary artery bypass surgery, chronic systolic heart failure, and chronic kidney disease presented initially with dyspnea on exertion and angina concerning for myocardial infarction, with no culprit lesion identified on angiography. He underwent cardiac MRI and endomyocardial biopsy which was consistent with ApoAIV amyloidosis. He was readmitted with acute angina and extreme elevation in coronary biomarkers, but repeat coronary angiography again did not show a culprit lesion. Right heart catheterization revealed cardiogenic shock, and he required intra-aortic balloon pump support.
Discussion: Cardiac amyloidosis commonly presents with diastolic heart failure and/or conduction abnormalities. ApoAIV amyloidosis is a rare form of amyloidosis whose clinical presentation is not very well characterized. This case highlights a rare manifestation of cardiac amyloidosis with acute coronary syndrome without changes in the epicardial coronary arteries. Instead, myocardial infarction was likely caused by microvascular coronary changes. Amyloidosis can less commonly cause obstruction of the coronary microvasculature which can lead to angina and ischemic changes as seen in this patient.
Conclusion: ApoAIV amyloidosis is a rare form of cardiac amyloidosis. It is important to maintain a high index of suspicion for microvascular dysfunction and/or obstruction from amyloidosis that can lead to clinical syndromes of myocardial ischemia and infarction.