Case Description
An 83-year-old male patient was referred to the cardiology department of our hospital due to acute myopericarditis. His medical history included hypertension, diabetes mellitus, dyslipidemia, permanent atrial fibrillation, hyperuricemia, and benign prostatic hyperplasia.
On admission, the patient was afebrile and hemodynamically stable. Laboratory tests showed high white blood cells (WBC) of 21.090 K/μL, elevated level of C-reactive protein (CRP) of 7.4 mg/dL [upper limit of normal (ULN): 0.5 mg/dL], erythrocyte sedimentation rate of 120 mm/h and an impaired renal function of 44 ml/min/1.73m2 [Glomerular Filtration Rate by the MDRD Equation- Creatinine level: 1.6 mg/dL]. High sensitive Troponin-T was elevated [132 pg/ml (ULN: 12 pg/ml)]. The QuantiFERON-TB Gold In Tube test was negative for Mycobacterium tuberculosis  infection. Virological blood test for herpesviruses IgM (cytomegalovirus, Epstein–Barr virus), enteroviruses IgM (echoviruses, coxsackieviruses), adenoviruses IgM, parvovirus IgM and human immunodeficiency virus were negative. COVID-19 (SARS-CoV-2) test was also negative. Thyroid hormones were within the normal limits. Rheumatoid factor, anti-nuclear antibodies and anti-neutrophil cytoplasmic antibodies were negative.
Echocardiography revealed a moderate circumferential pericardial effusion. Left ventricle had a normal systolic function, while the right ventricle had impaired systolic function [Decreased triscuid annular plane systolic excursion (TAPSE) measured with M-mode (7mm) and decreased peak systolic (S’) velocity of triscuid annulus (7 cm/s). Flattened interventricular septum (D-shaped left ventricle) was also observed at the parasternal short axis view. Inferior vena cava was distended (27mm) with diminished inspiratory collapsibility (<30%) (subcostal view). Subcostal view revealed a cyst-like lesion about 3.7 X 3.5 cm over the right atrioventricular groove with thickened walls and within it a calcified spherical formation (Fig. 1B ). After the intravenous injection of an ultrasound contrast agent there was a delayed entry of the contrast agent into the lesion (Supplemental Video 1 ). Chest computed tomography showed pericardial effusion and a lesion at the mid right coronary artery (RCA) (Fig. 1A ). Coronary angiography revealed a giant aneurysm of the mid-RCA (Fig. 1C ) with extravasation of the contrast media (Supplemental Video 2 ). The patient underwent an urgent surgical aneurysm resection and coronary artery distal bypass grafting. After the sternotomy, the pericardium was noted to be extremely inflamed with the presence of frank pus in the pericardial cavity (Fig. 1D) . Intraoperatively, RCA aneurysm was ruptured, while a bypass grafting of the RCA was performed with a saphenous vein graft. The patient died about 24 hours after the operation due to hemodynamic instability. Pericardial fluid cultures grew methicillin-sensitive Staphylococcus aureus .
The Histology (Fig. 2 ) revealed abundant thrombotic material, containing red blood cells and condensing fibrin, with a necrotic and partially hyalinised vascular wall (coronary artery) locally heavily infiltrated by transmural inflammatory cells. More recent thrombus elements were observed on the luminal surface of the artery (Fig. 2A, C ). Immunostaining for smooth muscle actin (SMA) showed markedly decreased or totally absent staining for SMA, due to loss of smooth muscle cells (Fig. 2B ). Immunostaing for elastin fibers (Elastica IHC) showed complete loss of elastic fibers. Numerous bacterial aggregates (clumps) were detected in Hematoxylin-Eosin (H-E) stain (Fig. 2C ) and identified by Gram stain (Fig. 2D ). The histopathology was consistent with a “mycotic” (infected) aneurysm of the mid-RCA.