Mitral Stenosis is the Most Common Murmur in Chronic Rheumatic Heart Disease
The answer is C: Mitral stenosis. Mitral stenosis represents the hallmark valvular lesion of chronic rheumatic heart disease, characterized by middiastolic and presystolic murmurs that are "usually due to mitral or tricuspid stenosis" 1, 2.
Clinical Reasoning
Why Mitral Stenosis Predominates
The pathophysiology of rheumatic heart disease involves chronic inflammatory damage to valve leaflets, with the mitral valve being the most frequently and severely affected structure. The guidelines clearly state that middiastolic and presystolic murmurs are usually due to mitral or tricuspid stenosis 1, 2, 1.
Supporting Evidence from Clinical Studies
Recent clinical data reinforces this pattern:
- In a prospective study of 47 RHD patients, mitral stenosis (MS) was present in 85.1% of cases 3
- Mitral valve leaflet thickening and calcification with restricted motion was documented in 91.5% of patients 3
- The most common presentations involved combinations of mitral stenosis with other valvular lesions 3
The Murmur Characteristics
The mitral stenosis murmur in RHD presents as:
- Middiastolic rumbling murmur occurring early during ventricular filling
- Presystolic accentuation (when sinus rhythm is present) following atrial contraction
- Low-pitched quality best heard at the apex with the bell of the stethoscope
- Often accompanied by an opening snap 1, 2
Why Not the Other Options?
Mitral Regurgitation (Option B)
While mitral regurgitation is indeed common in RHD (87.2% in one study 3), it typically occurs in combination with mitral stenosis rather than in isolation. The pansystolic murmur of MR was reported in 91.5% of patients, but this reflects the mixed valvular disease pattern where stenosis remains the defining lesion 3.
Aortic Regurgitation (Option A)
Aortic regurgitation produces an early diastolic, high-pitched, decrescendo murmur 1. While it can occur in RHD, it is less common than mitral involvement and typically develops later in the disease course.
Pulmonary Stenosis (Option D)
Pulmonary stenosis is not a characteristic feature of rheumatic heart disease. RHD primarily affects left-sided valves, with the mitral valve being most susceptible to rheumatic inflammation.
Clinical Pitfalls to Avoid
Don't assume a pansystolic murmur rules out mitral stenosis. Many RHD patients have mixed mitral disease with both stenosis and regurgitation. The combinations of three (MR+MS+TR) and four (MR+MS+TR+AR) valve diseases were most commonly reported 3.
Don't rely solely on auscultation. The guidelines emphasize that echocardiography should be performed routinely in RHD patients to accurately characterize valvular lesions before complications develop 4, 3. Clinical examination alone may miss the severity of stenosis, particularly in early disease.
Remember that atrial fibrillation is common (48.9% of patients 3), which eliminates the presystolic component of the mitral stenosis murmur, leaving only the middiastolic rumble.