Non-Bacterial Thrombotic Endocarditis with Resultant Embolic Infarcts in a Patient with Lupus

Description of Clinical Presentation: A 36-year-old female presented with worsening dyspnea, bilateral lower extremity edema, and pleuritic chest pain for one week. Her history was notable for uncontrolled hypertension, systemic lupus erythematous with lupus nephritis, antiphospholipid syndrome, prior TIA, and medication non-compliance. On arrival, she had a blood pressure of 197/118. Hs-troponin was elevated to 35, BNP to 1518, ESR to 101, and CRP to 13.1. Infectious work-up was negative. ECG was concerning for pericarditis. Echocardiogram on admission showed a trileaflet aortic valve with severely thickened leaflets, moderate-severe aortic stenosis, and an attached small immobile mass. Left heart catheterization showed nonobstructive coronary artery disease. Cardiac MRI was ordered to elucidate the cause of her myocardial infarction with nonobstructive coronary artery disease (MINOCA), assess the pericardium, and clarify the mass on the aortic valve.

Diagnostic Techniques and Their Most Important Findings: Cardiac MRI showed normal biventricular function and a trileaflet aortic valve with moderate AS (peak velocity between 3.25-4.0 m/s) and mild AI. There was diffuse calcification and/or thrombosis of the aortic leaflets with focal mass-like thickening along the aortic aspect of the non-coronary and left coronary cusps suggestive of nonbacterial thrombotic endocarditis (NBTE). Additionally, there were focal subendocardial infarctions of both the basal lateral and basal inferior walls, consistent with coronary embolic phenomena. The ascending aorta was mildly dilated at 4.0 x 4.1 cm. There was mild LV dilation and hypertrophy (maximal wall thickness 1.2 cm) and elevated LV mass (215.1 g) suggestive of hypertensive heart disease. There was no pericardial enhancement.

Learning Points from this Case: This 36-year-old patient with lupus who presented with MINOCA was found to have NBTE and embolic infarcts on cardiac MR imaging. Our case demonstrates the critical utility of CMR in diagnosing the underlying cause of MINOCA, revealed an unusual and unexpected finding, and helped to guide further management. NBTE poses risks of serious complications, including heart failure, fatal arrhythmias, and embolic infarcts (i.e. stroke, myocardial infarction, acute limb ischemia, mesenteric ischemia). CMR revealed the surprising finding of multiple small infarctions, presumably embolic from the aortic valve. The presence of embolic infarcts on CMR suggested a higher risk of further embolic events, assisting in risk stratification and leading to expedited aortic valve replacement. While there is limited information on direct comparison of CMR and TTE/TEE for diagnosis of endocarditis, our case contributes to a body of work in which CMR has been advantageous in identifying aortic valve disease as a possible cause of MINOCA and driving inpatient management in a patient with autoimmune disease.

Trileaflet aortic valve with diffuse calcification and thrombosis of the leaflets with focal mass-like thickening along the aortic aspect of the non/left cusps (A, B). Moderate aortic stenosis with a planimetered AVA estimated 1.32 cm2 (C).
Short axis (A-C) and two-chamber (D) views demonstrating small focal subendocardial infarctions of the basal lateral and inferior walls.
Thru-plane velocity flow mapping of the aortic valve showing aliasing at an encoding velocity of 3.25 m/s (A) that resolves at 4 m/s (B). In-plane velocity flow mapping in LVOT view (C) revealing aortic turbulence. The peak aortic velocity is estimated between 3.25 and 4.0 m/s, consistent with moderate stenosis.