Mitral valve prolapse (MVP) is one of those Step-friendly diagnoses that hides in plain sight: a young, otherwise healthy patient with “weird” chest symptoms and a click you only hear if you listen the right way. Q-banks love MVP because they can test (1) classic auscultation maneuvers, (2) when to worry about complications, and (3) how to not get baited by look-alike murmurs.
Tag: Cardiovascular > Valvular Heart Disease
The Vignette (Q-bank style)
A 24-year-old woman comes to clinic for intermittent palpitations and brief episodes of sharp left-sided chest pain that occur at rest. She has no dyspnea on exertion. No syncope. No fever or IV drug use. Family history: her mother has “a heart murmur.” Vitals are normal. On cardiac exam, you hear a mid-systolic click followed by a late systolic murmur best at the apex. When she stands up from squatting, the click occurs earlier, and the murmur becomes longer.
Question: What is the most likely underlying abnormality causing her murmur?
Answer choices
A. Myxomatous degeneration of the mitral valve leaflets
B. Calcific degeneration of the aortic valve cusps
C. Failure of neural crest cell migration causing abnormal aorticopulmonary septation
D. Rheumatic heart disease with commissural fusion and chordae tendineae thickening
E. Left ventricular dilation causing papillary muscle displacement and incomplete mitral closure
The Correct Answer: A. Myxomatous degeneration of the mitral valve leaflets
Why it’s MVP
MVP is classically due to myxomatous degeneration (a “floppy” valve) leading to billowing of one or both mitral leaflets into the left atrium during systole. The auscultation pattern is key:
- Mid-systolic click = sudden tensing of chordae/leaflets as the valve prolapses
- Late systolic murmur = mitral regurgitation that begins after the prolapse occurs
- Best heard at the apex
Why the maneuvers matter (this is the exam “tell”)
MVP changes with LV volume:
| Maneuver | LV volume | MVP click/murmur |
|---|---|---|
| Standing / Valsalva | ↓ | Earlier click, longer murmur |
| Squatting / Leg raise | ↑ | Later click, shorter murmur |
Mechanism: Smaller LV volume = chordae/leaflets become relatively “looser,” so prolapse happens sooner in systole.
High-yield associations
- Often benign, but can be associated with:
- Mitral regurgitation (progressive)
- Arrhythmias (palpitations)
- Infective endocarditis risk increases if significant MR is present (note: routine prophylaxis is not for uncomplicated MVP)
- Connective tissue disorders:
- Marfan syndrome, Ehlers-Danlos
- Symptoms can include atypical chest pain, anxiety, palpitations
Now, Why Every Other Answer Choice Is Wrong (and what they’re trying to bait you into)
B. Calcific degeneration of the aortic valve cusps
This is aortic stenosis (AS) from age-related calcification (or earlier in bicuspid valves).
What you’d expect instead
- Older patient (classically >65; younger if bicuspid)
- Crescendo–decrescendo systolic murmur at right upper sternal border
- Radiates to carotids
- Symptoms: SAD (Syncope, Angina, Dyspnea)
Maneuver clue: AS intensity usually increases with squatting (increased preload).
Why it’s wrong here: the vignette gives mid-systolic click + late systolic apical murmur with MVP maneuvers—not an ejection murmur radiating to the neck.
C. Failure of neural crest cell migration causing abnormal aorticopulmonary septation
Neural crest migration defects are congenital outflow tract problems (conotruncal anomalies), e.g.:
- Tetralogy of Fallot
- Persistent truncus arteriosus
- Transposition of the great arteries (more complex embryology, but classically tested among conotruncal topics)
- Interrupted aortic arch
What you’d expect instead
- Cyanosis, harsh murmurs, abnormal pulses depending on lesion
- Presentation in infancy/childhood, not an isolated adult click-murmur pattern
Why it’s wrong here: MVP is a valvular/leaflet problem, not a conotruncal septation defect.
D. Rheumatic heart disease with commissural fusion and chordae tendineae thickening
Rheumatic fever causes chronic valvular damage via immune cross-reactivity after group A strep pharyngitis. The most classic chronic lesion is mitral stenosis (MS), though MR can occur earlier.
What you’d expect instead
- History suggesting prior rheumatic fever: migratory polyarthritis, carditis, Sydenham chorea, erythema marginatum, subcutaneous nodules
- Murmur of mitral stenosis:
- Opening snap after S2 + diastolic rumble at the apex
- Often with left atrial enlargement → atrial fibrillation
- Structural hallmark: commissural fusion, “fish-mouth” valve
Why it’s wrong here: the vignette is systolic click + late systolic murmur (MVP), not opening snap/diastolic rumble.
E. Left ventricular dilation causing papillary muscle displacement and incomplete mitral closure
This describes functional (secondary) mitral regurgitation, often due to:
- Dilated cardiomyopathy
- Ischemic cardiomyopathy (post-MI remodeling)
- Heart failure with reduced EF
What you’d expect instead
- Symptoms/signs of heart failure: dyspnea, orthopnea, edema, S3
- A holosystolic blowing murmur at apex radiating to axilla (MR)
- Often no click (click points you toward MVP)
Why it’s wrong here: this patient is young, no HF symptoms, and the murmur is late systolic with a click—not holosystolic MR from LV dilation.
Quick Pattern Recognition: MVP vs the Big Look-Alikes
| Condition | Key sound | Murmur timing | Best heard | Maneuver that increases |
|---|---|---|---|---|
| MVP | Mid-systolic click | Late systolic | Apex | Standing / Valsalva |
| MR (primary/functional) | None | Holosystolic | Apex → axilla | Handgrip (↑ afterload) |
| AS | None (sometimes ejection click in bicuspid AS) | Systolic ejection | RUSB → carotids | Squatting (↑ preload) |
| MS (rheumatic) | Opening snap | Diastolic rumble | Apex | Exercise/left lateral position |
USMLE High-Yield Takeaways (memorize these)
- MVP = myxomatous degeneration → mid-systolic click + late systolic murmur
- Standing/Valsalva (↓ preload) → MVP happens earlier → click earlier, murmur longer
- Squatting (↑ preload) → MVP happens later → click later, murmur shorter
- MVP can be associated with Marfan/Ehlers-Danlos, palpitations, and MR
- Don’t confuse:
- Click (MVP) vs opening snap (MS)
- Late systolic (MVP) vs holosystolic (MR)
One Last “Q-bank move”: what if they ask management?
A common Step framing is “next best step” after diagnosis:
- Asymptomatic MVP with minimal MR: reassurance ± periodic follow-up
- Significant MR or symptoms: echocardiography, manage MR, consider repair depending on severity/ventricular function
- Endocarditis prophylaxis: not for uncomplicated MVP; reserved for highest-risk cardiac conditions (e.g., prosthetic valves, prior endocarditis, certain congenital lesions, transplant with valvulopathy)