Multivessel Epicardial Coronary Artery Thrombosis after Heart Transplantation

ABSTRACT

Introduction: Although cardiac allograft vasculopathy (CAV) remains one of the leading causes of graft failure after heart transplantation (HTx), simultaneous thrombosis of multiple epicardial coronary arteries (CA) is an uncommon finding. Case Report A 43-year-old male patient with non-ischemic dilated cardiomyopathy underwent successful HTx in 2019. The first two years after HTx were uneventful, surveillance endomyocardial biopsies (EMB) did not reveal any rejection episodes, coronary CTA revealed only minimal non-calcified CA plaques. The patient was admitted to hospital due to fever and chest pain in 2021. Immunosuppressive therapy consisted of tacrolimus, mycophenolate-mofetil and methylprednisolone. ECG verified sinus rhythm. Laboratory test revealed elevated hsTroponin T, NT-proBNP and CRP levels. Cytomegalovirus, SARS-CoV-2-virus and hemoculture testing was negative. Several high-titre donor-specific HLA class I and II antibodies (DSAs;including complement-binding DQ7) could have been detected since 2020. Echocardiography confirmed mildly decreased left ventricular systolic function and apical hypokinesis. EMB verified mild cellular and antibody-mediated rejection (ABMR) according to ISHLT grading criteria. Cardiac MRI revealed inferobasal and apical myocardial infarction (MI);thus, an urgent coronary angiography was performed. This confirmed thrombotic occlusions in all three main epicardial CAs and in first diagonal CA. As revascularization was not feasible, antithrombotic therapy with acetylsalicylic acid, clopidogrel and enoxaparin was started for secondary prevention. Tests for immune system disorders, thrombophilia and cancer were negative. Patient suddenly died ten days after admission. Necropsy revealed intimal proliferation in all three main epicardial CAs, endothelitis, thrombosis, chronic pericoronary fat inflammation, fat necrosis, and subacute MI. CA vasculitis owing to persistent high-titre DSAs, chronic ABMR and acute cellular and antibody-mediated rejection led to multivessel CA thrombosis and acute multiple MI. ABMR after HTx may be underdiagnosed with traditional pathological methods. Pathologies affecting coronary vasculature of HTx patients with DSAs, unique manifestations of CAV lesions and occlusive thrombosis of non-stenotic, non-atherosclerotic lesions should be emphasized.Copyright © 2023