Left atrial mural infective endocarditis complicated by coronary embolism and left ventricular myocardial infarction in a cat.

A three-year-old female Devon Rex was referred for postpartum complications. On presentation, physical examination revealed depression, hypothermia, pale mucous membranes and a grade II/VI left apical systolic murmur. Laboratory tests showed severe non-regenerative anaemia, moderate leucocytosis and increased cardiac troponin I (4.16 ng/mL; upper hospital limit <0.2 ng/mL). Transthoracic echocardiography showed no remodelling or dysfunction of either cardiac chamber and no valvular abnormalities. However, a 6-mm echogenic structure with well-defined margins was identified in the left atrial (LA) cavity, apparently adherent to the mural endocardium. Differential diagnosis initially included a LA mural endocarditis and a LA thrombus. The cat was hospitalized and treated with packed red blood cells, ampicillin-sulbactam, enoxaparin and clopidogrel. On day 2, the cat developed acute aortic thromboembolism, rapidly followed by cardiac arrest. The owner consented to a partial postmortem examination limited to the heart. Gross and histological findings were consistent with multisite infective endocarditis (IE) without valvular involvement, featuring LA mural vegetation and pulmonary venous thrombosis, complicated by coronary embolism and an acute left ventricular myocardial infarction. These findings appear to be unique according to the existing feline literature, as in previously described cats with IE, the pathological process involved the mitral and/or aortic valves and primarily led to congestive heart failure or arrhythmias. However, they are consistent with IE cases described in human medicine. This report therefore provides additional insight into feline IE, indicating that, in cats - as already documented in humans - the condition can also present with atypical manifestations and complications.