Can be primary or secondary. Unclear whether aPLs are responsible for hypercoagulable state or merely an epiphenomenon. Most usual valve affected is mitral followed by aortic. Propensity for ventricular surface of mitral valve. Typically sessile, wartlike and small, usually varying from pinhead size to 4 mm.
Predominant location is on middle or proximal portion of leaflet or cusps.
Minor, if any, hemodynamic significance is the norm. Frequent occurrence of aPLS, valvular disease and thromboembolic events. On TTE, vegetations appear indistinguishable from those of infective endocarditis. Immune complexes play probable role. After alteration of valve occurs, formation of fibrin-platelet thrombi takes place.