Characteristic Murmur in Mitral Valve Prolapse
The characteristic murmur heard in mitral valve prolapse is a late systolic murmur, which is typically preceded by a midsystolic click. 1, 2
Auscultatory Features
The classic auscultatory findings in mitral valve prolapse include:
- Midsystolic click followed by a late systolic murmur (the "click-murmur syndrome") 2, 3
- The murmur is typically:
- Soft to moderately loud
- High-pitched
- Best heard at the left ventricular apex
- Starts well after ejection (after the click)
- Ends before or at the second heart sound (S2) 1
The late systolic murmur results from late systolic regurgitation due to prolapse of the mitral leaflet(s) into the left atrium 1. In some cases, the late systolic murmur can occur without an audible click 1.
Dynamic Auscultatory Changes
The intensity and timing of the click and murmur in mitral valve prolapse change characteristically with various maneuvers:
| Maneuver | Effect on MVP Murmur |
|---|---|
| Valsalva | The murmur becomes longer and often louder [1,4] |
| Standing | The murmur lengthens and often intensifies [1,4] |
| Squatting | The murmur usually softens and may disappear [1,4] |
These dynamic changes help differentiate mitral valve prolapse from other cardiac murmurs and are important diagnostic features.
Variations in Presentation
While the classic presentation is a midsystolic click followed by a late systolic murmur, several variations exist:
- Early systolic clicks (occurring less than 80 msec from S1) can be present in some patients with mitral valve prolapse 5
- Some patients may have only a click without a murmur 5
- In rare cases, patients may have diastolic sounds or early diastolic murmurs in addition to the systolic findings 6
- Some patients may have "silent" mitral valve prolapse with no audible murmur or click despite echocardiographic evidence of prolapse 5
Clinical Significance
The presence of a late systolic murmur in mitral valve prolapse indicates mitral regurgitation. While most patients with mitral valve prolapse have a benign course, some may develop:
Key Points for Clinicians
- Always perform dynamic auscultation (Valsalva, standing, squatting) when suspecting mitral valve prolapse
- Echocardiography is recommended to confirm the diagnosis, especially in patients with atypical presentations 5
- Antibiotic prophylaxis should be considered for patients with mitral valve prolapse prior to certain procedures 7
- Beta-blockers may be beneficial for patients with symptomatic arrhythmias or chest pain 7