What are the expected physical cardiac exam findings in a patient with anterior mitral valve prolapse with regurgitation?

Physical Cardiac Exam Findings in Anterior Mitral Valve Prolapse with Regurgitation

The hallmark finding is a nonejection midsystolic click followed by a late systolic murmur that extends to S2, best heard at the apex with possible radiation to the axilla. 1

Primary Auscultatory Findings

The Midsystolic Click

• A nonejection midsystolic click represents the sudden tensing of the mitral valve apparatus as the anterior leaflet prolapses into the left atrium during systole. 1
• The click may occur as a single sound or as multiple clicks, and its timing moves within systole with changes in left ventricular dimensions. 1
• In some patients, the click may be the only finding without an accompanying murmur. 2

The Systolic Murmur

• In mild-to-moderate anterior MVP with regurgitation, expect a late systolic murmur that begins after the midsystolic click and extends to S2. 1
• The murmur is best heard at the apex and may radiate to the axilla. 1
• In severe MVP with regurgitation, a loud holosystolic murmur may be heard at the apex, though this is less common. 1
• The incidence and intensity of murmurs increases with age and severity of regurgitation. 3

Critical Timing Considerations for Anterior Leaflet Prolapse

A very late soft systolic murmur without diastolic filling sounds indicates that regurgitation occurs only in very late systole, which is frequently overestimated by echocardiography. 1 This is particularly important because:

• The effective regurgitant orifice in MVP increases throughout systole, with the largest orifice occurring in late systole. 4
• Despite appearing severe on single-frame echocardiographic assessment, the shorter duration of late systolic regurgitation yields lower total regurgitant volume. 5
• Mid-late systolic MR causes more benign consequences and outcomes than holosystolic MR, even when instantaneous measurements appear similar. 5

Additional Cardiac Findings

Heart Sounds

• Normal intensity and splitting of S2 is typically preserved in mild MVP. 1
• An early diastolic filling sound (S3) may be present in severe mitral regurgitation with significant volume overload. 1

Signs of Hemodynamic Severity

• Normal left ventricular and left atrial examination findings (no displaced PMI, no left atrial lift) suggest that severe chronic mitral regurgitation is unlikely, even if echocardiography suggests otherwise. 1
• Signs of pulmonary congestion (rales, elevated JVP) may be present in severe regurgitation with hemodynamic compromise. 1

Dynamic Maneuvers to Enhance Detection

Decreasing Left Ventricular Volume

• Standing from squatting or Valsalva maneuver decreases left ventricular volume, causing the click to occur earlier in systole and the murmur to become longer and louder. 1
• This maneuver is particularly useful for detecting subtle MVP that may be missed on routine examination. 1

Increasing Left Ventricular Volume

• Squatting or leg raising increases left ventricular volume, causing the click to occur later in systole and the murmur to become shorter and softer. 1

Common Pitfalls to Avoid

Examination Technique Errors

• Failing to examine in multiple positions (supine, left lateral decubitus, standing) may miss MVP, as the physical examination in these positions is optimal for detection. 1
• Misinterpreting grade 1-2 systolic ejection murmurs at the left sternal border as MVP when they actually represent innocent flow murmurs. 1

Misinterpreting Anterior Leaflet Override

• In secondary MR with left ventricular dysfunction, the anterior leaflet may appear to override the posterior leaflet at end-systole, mimicking prolapse. 6
• However, in true anterior MVP, the leaflet moves superiorly beyond the mitral annular plane into the left atrium, whereas in secondary MR, both leaflets remain tethered into the ventricle throughout systole. 6

Reconciling Physical Exam with Echocardiography

• When physical examination shows only a very late soft systolic murmur with normal chamber findings, but echocardiography suggests severe MR, the echocardiogram likely overestimates severity by not accounting for the short duration of late systolic regurgitation. 1
• Conversely, when physical examination suggests severe MR but echocardiography shows only mild regurgitation, the echocardiogram likely underestimates severity due to technical limitations with eccentric jets. 1

Timing-Related Pitfalls

• Using single-frame echocardiographic measurements (like PISA) in late systolic MR overestimates severity because it captures the instantaneous maximum orifice without accounting for the brief duration of regurgitation. 5, 4
• The effective regurgitant orifice can increase from 32 mm² in early systole to 107 mm² in late systole in MVP patients, but total regurgitant volume may still be modest due to the short duration. 4

Spectrum of Physical Findings

• Approximately 23% of patients have only a click without a murmur. 2
• Approximately 23% have a late systolic murmur. 3
• Approximately 16% have a pansystolic murmur, more common in males and with increasing age. 3
• Approximately 18% may have neither a click nor a murmur despite echocardiographic evidence of MVP. 3