Myocardial infarction with “clean coronaries” caused by amyloid light-chain AL amyloidosis: a case report and literature review

In AL (amyloid light-chain) amyloidosis, the greatest risk of death occurs in patients with cardiac involvement, who typically develop diastolic dysfunction and then systolic heart failure, with predisposition to arrhythmias and sudden death. Here, we present an alternate variation of cardiac amyloidosis. This patient had recent non-obstructive coronary angiography, yet suffered a fatal myocardial infarction shortly after stem cell collection and mobilization in preparation for treatment with high-dose melphalan and autologous stem cell transplantation (HDM/SCT). On autopsy, widespread deposition of amyloid was found in the small vessels of the heart with evidence of associated acute infarction. While the typical presentation of cardiac amyloidosis is an infiltrating restrictive cardiomyopathy, this case report and literature review illustrate that ischemic small vessel amyloidosis may also occur. Small vessel coronary disease and associated myocardial ischemia should be considered in patients with AL amyloidosis with angina, as its presence may increase treatment-related complications. Contemporary testing should aim to detect both forms of cardiac amyloidosis, which may impact management and prognosis.