What are the typical clinical signs and symptoms of mitral regurgitation?

Clinical Signs of Mitral Regurgitation

The hallmark physical examination finding in mitral regurgitation is a holosystolic murmur heard best at the apex with radiation to the axilla, though the specific characteristics vary significantly based on the underlying mechanism and severity. 1

Primary Auscultatory Findings

Acute Severe Mitral Regurgitation

• A loud holosystolic murmur at the apex with radiation to the axilla is the classic finding, accompanied by an early diastolic filling sound (S3) 1
• In cases of flail leaflet from papillary muscle or chordae rupture, expect an eccentric jet directed away from the defective leaflet, with the murmur potentially being very loud 1
• Critical pitfall: Severe mitral regurgitation can be "silent" (no audible murmur) in up to 10% of cases, particularly when the regurgitant jet is eccentric and directed posteriorly, impinging on the atrial wall 2
• When a loud holosystolic murmur and early diastolic filling sound are present with new-onset dyspnea, this strongly suggests severe mitral regurgitation requiring urgent evaluation 1

Chronic Primary Mitral Regurgitation

• Holosystolic murmur at the apex, best heard with the patient in the left lateral decubitus position 1, 3
• The murmur intensity does not reliably correlate with severity—eccentric jets may produce softer murmurs despite being hemodynamically severe 1
• S3 gallop indicates significant volume overload and suggests at least moderate-to-severe regurgitation 1, 4
• A diastolic flow rumble may be audible at the apex when regurgitant volume is large enough to cause increased flow across the mitral valve in diastole 4

Mitral Valve Prolapse with Regurgitation

• Nonejection midsystolic click followed by a late systolic murmur extending to S2, best heard at the apex 5, 3
• The click represents sudden tensing of the mitral valve apparatus as leaflets prolapse into the left atrium 5, 3
• A very late soft systolic murmur without diastolic filling sounds indicates regurgitation occurs only in very late systole and suggests mild-to-moderate severity 5
• Dynamic maneuvers are diagnostically critical: Standing or Valsalva decreases left ventricular volume, causing the click to occur earlier and the murmur to become longer and louder 5, 3
• Squatting or leg raising increases left ventricular volume, causing the click to occur later and the murmur to become shorter and softer 5, 3

Secondary (Functional) Mitral Regurgitation

• Often produces a softer, less impressive systolic murmur despite hemodynamic significance, as the regurgitation may be non-holosystolic or biphasic 1
• The murmur is typically loudest at the apex but may be less prominent than expected for the degree of regurgitation 1
• Important distinction: In the context of hypertrophic cardiomyopathy with outflow obstruction, mitral regurgitation is usually mild-to-moderate and the jet is typically directed posteriorly 1

Additional Cardiac Examination Findings

Signs of Volume Overload

• Laterally displaced and hyperdynamic apical impulse indicates left ventricular dilation from chronic volume overload 6, 7
• Prominent left ventricular heave suggests significant left ventricular enlargement 6
• Normal left ventricular and left atrial examination findings make severe chronic mitral regurgitation unlikely, even if echocardiography suggests otherwise 1, 5

Pulmonary Findings

• Pulmonary rales or crackles indicate pulmonary congestion from elevated left atrial pressure 4, 8
• Signs of pulmonary hypertension (loud P2, right ventricular heave) develop with chronic severe regurgitation 3, 4
• In acute severe mitral regurgitation, frank pulmonary edema may be present with respiratory distress 8

Heart Sounds

• Normal S2 splitting is typically preserved in mild-to-moderate mitral regurgitation 5
• S3 gallop is a critical finding suggesting significant volume overload and hemodynamic compromise 1, 4
• Soft or absent S1 may occur in severe acute mitral regurgitation with flail leaflet 1

Critical Diagnostic Pitfalls

Common Misinterpretations

• Failing to recognize "silent" severe mitral regurgitation: Up to 10% of hemodynamically critical cases have no audible murmur, particularly with eccentric jets 2
• Misinterpreting anterior leaflet override in secondary mitral regurgitation as prolapse: In dilated cardiomyopathy, the anterior leaflet may appear to override the tethered posterior leaflet, but this is NOT prolapse—the leaflet never moves superior to the annular plane 1, 5
• Underestimating severity based on murmur intensity alone: Eccentric jets lose energy as they impinge on the atrial wall, producing softer murmurs despite severe regurgitation 1
• Overlooking dynamic changes: Secondary mitral regurgitation severity can vary significantly with loading conditions, blood pressure, and heart rate 1

When Physical Examination and Echocardiography Disagree

• If physical examination suggests severe mitral regurgitation (loud holosystolic murmur, S3, signs of volume overload) but echocardiography shows only mild regurgitation, the echo likely underestimated severity due to eccentric jet or technical limitations 1
• If echocardiography suggests severe mitral regurgitation but examination shows only a very late soft murmur with normal chamber findings, the echo likely overestimated severity by not accounting for late systolic-only regurgitation 1, 5
• Always directly review echocardiographic images rather than relying solely on the report, and ensure concordance between clinical findings and imaging 1

Symptoms Associated with Clinical Signs

• Exertional dyspnea, orthopnea, and paroxysmal nocturnal dyspnea correlate with elevated left atrial pressure from significant regurgitation 4, 7
• Fatigue and exercise intolerance result from reduced forward cardiac output 7
• Palpitations may indicate atrial fibrillation, which commonly develops with chronic left atrial enlargement 4
• In acute severe mitral regurgitation, cardiogenic shock and pulmonary edema may dominate the clinical presentation 8