Pathology in SLE Leading to Mitral Stenosis
The pathology in SLE that leads to mitral stenosis is Libman-Sacks endocarditis, which causes sterile verrucous vegetations composed of immune complexes, fibrin, and inflammatory tissue that deposit on valve leaflets, leading to valve thickening, fibrosis, and ultimately stenosis, though mitral regurgitation is far more common than stenosis in SLE.
Pathophysiologic Mechanism
Libman-Sacks endocarditis is the characteristic cardiac manifestation of SLE that affects valvular structures through a specific immunologic process 1, 2:
- Immunoglobulin and complement deposition occurs directly in the valvular structure, initiating an inflammatory cascade 2
- This deposition leads to formation of sterile verrucous vegetations made of inflammatory tissue, immune complexes, and fibrin on cardiac valves 1, 3
- The chronic inflammatory process results in valve thickening, fibrosis, and restricted leaflet motion 2, 4
- Basal endocardial thickening with extensive fibrous endocarditis can develop, as demonstrated on cardiac MRI with delayed enhancement patterns 4
Clinical Pattern and Valve Involvement
The mitral valve is most frequently affected in SLE, but the typical manifestation differs from stenosis 2:
- Mitral regurgitation is the predominant lesion in SLE valvulopathy, not stenosis 1, 2, 3
- Mitral stenosis is rarely seen in SLE and represents an uncommon manifestation of Libman-Sacks endocarditis 1, 2, 4
- When stenosis does occur, it results from severe structural involvement with marked valve thickening and restricted leaflet motion from the inflammatory and fibrotic process 4
Important Clinical Caveat
This differs fundamentally from rheumatic mitral stenosis, which remains the most common cause of mitral stenosis worldwide and is responsible for 95-99.3% of all mitral stenoses in individuals aged <50 years 5. The guideline evidence emphasizes that other causes such as inflammatory carditis from SLE can be excluded by clinical context when evaluating mitral stenosis 5.
Diagnostic Considerations
When SLE-related mitral stenosis is suspected:
- Cardiac MRI is particularly valuable for demonstrating thickening of the mitral valve with basal endocardial thickening, defects on first-pass perfusion, and delayed enhancement consistent with extensive fibrous endocarditis 4
- Transesophageal echocardiography is the most sensitive method to detect valvular involvement in SLE 2
- The imaging helps differentiate Libman-Sacks endocarditis from valve tumors and infective endocarditis with perivalvular abscesses 4
Surgical Implications
When severe mitral stenosis from Libman-Sacks endocarditis requires intervention 1, 6:
- Surgical decision depends on structural involvement of the mitral valve, presence of active lupus nephritis, and antiphospholipid antibody syndrome 1
- Medical stabilization of underlying SLE with immunosuppressive therapy should be achieved before surgical intervention when possible 3
- Association of antiphospholipid antibody syndrome with SLE has a negative impact on surgical outcomes 1
- Mechanical valve replacement eliminates the risk of recurrent Libman-Sacks endocarditis on the prosthetic valve 3