**3. Pathogenesis**

 NBTE is a type of noninfectious endocarditis whose physiopathology continues to be unknown. It is characterized by the deposition of sterile platelet thrombi in the heart valves. In certain situations of hypercoagulability, endothelial damage occurs that favors the migration of mononuclear inflammatory cells and platelet deposition, being these responsible for the formation of fibrin thrombi and immune complexes (thrombi known as "white thrombus"). The term Libman-Sacks is used when you see a large thrombus or "wart" (verrucous endocarditis).

 One of the main and differential characteristics of this entity is that the valvular vegetations must always be sterile (unlike infectious endocarditis (IE)). The mitral and aortic valves are the most frequently affected (rare right endocarditis), and it is common for NBTE to appear on healthy native valves, endocardium, or chordae tendineae.

Unlike IE, vegetations of the NBTE are more friable because they develop on a tissue with an important inflammatory reaction. This makes them more likely to produce systemic embolisms. They are located in the valvular coaptation lines and

#### **Figure 1.**

*ETE-3D: Three-dimensional view of the aortic valve showing a rupture of the left coronary leaflet with images suggesting multiple vegetations of the valve in a 56-year-old man with Libman-Sacks endocarditis and SLE. ETE-Velos: Short axis view of the aortic valve showing a rupture of the left coronary leaflet with images suggesting thickening and multiple vegetations in the leaflets.* 

are generally not accompanied by destruction of the valvular tissue. In terms of their size, they tend to be smaller and develop on a broad and irregular basis [9].

In NBTEs associated with malignancy, it is believed that macrophages interact with tumor cells, causing a migration of cytokines (tumor necrosis factor, interleukin-1, etc.) that produces endothelial tissue damage and the formation of friable thrombi due to the deposition of platelets. On the other hand, the macrophagetumor cell interaction favors overactivation of the coagulation cascade, which in turn worsens the state of hypercoagulability that underlies the process. For this reason, NBTE tends to develop around areas of greater valve turbulence [3].

 Libman-Sacks endocarditis is the most characteristic cardiac manifestation of SLE, with pericarditis being the most frequent cardiac manifestation [10]. It was first described in 1924, by Libman and Sacks at Mount Sinai Hospital in New York. From the macroscopic point of view, these deposits, usually located on the ventricular surface of the posterior leaflet of the mitral valve, are translated into vegetations with progressive growth or only thickening of the leaflets (**Figure 1**). The classic histopathological lesion consists of a deposit of fibrin and mononuclear cells. The immunofluorescence reveals immunoglobulin deposit and complement. Valvular involvement is usually silent and occurs in approximately half of patients with SLE, although in some cases valvular dysfunction can be the origin of heart failure. As in other NBTEs, the mitral and aortic valves are affected more frequently than those on the right side, with valvular insufficiency prevailing over the stenosis. The presence of lupus anticoagulant increases the risk of suffering thrombotic and embolic phenomena in these patients [11].
