What are the clinical features of mitral regurgitation?

Clinical Features of Mitral Regurgitation

Auscultatory Findings

The hallmark physical examination finding in mitral valve prolapse with regurgitation is a nonejection midsystolic click followed by a late systolic murmur that extends to S2. 1

Primary Auscultatory Characteristics

• Midsystolic click: Represents sudden tensing of the mitral valve apparatus as leaflets prolapse into the left atrium during systole; may occur as single or multiple clicks with timing that varies based on left ventricular dimensions 1

• Late systolic murmur: In mild-to-moderate mitral regurgitation, the murmur begins after the midsystolic click and extends to S2, best heard at the apex with radiation to the axilla 1

• Holosystolic murmur: In severe mitral regurgitation, a loud holosystolic murmur may be present at the apex, though this is less common 1

• S3 gallop: An early diastolic filling sound may be present in severe mitral regurgitation with significant volume overload 1

Dynamic Maneuvers

• Standing or Valsalva: Decreases left ventricular volume, causing the click to occur earlier in systole and the murmur to become longer and louder 1

• 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

Symptoms

Acute vs. Chronic Presentation

• Asymptomatic phase: Many patients remain asymptomatic for extended periods as the heart compensates through left atrial enlargement 2, 3

• Dyspnea: Progressive shortness of breath, initially with exertion and eventually at rest, develops as pulmonary venous hypertension worsens 3

• Orthopnea: Difficulty breathing when lying flat occurs due to increased pulmonary venous congestion 3

• Fatigue: Results from reduced forward cardiac output and chronic volume overload 3

• Arrhythmias: Atrial fibrillation commonly develops due to chronic left atrial dilation and increased left atrial pressure; can be either a consequence or cause (atrial functional mitral regurgitation) 4

Hemodynamic Consequences

Left Ventricular Effects

• Volume overload: The left ventricle ejects blood through two pathways—a low-impedance path through the incompetent mitral valve into the left atrium and a higher-impedance path through the aortic valve 5

• Left ventricular dilation: Progressive chamber enlargement occurs as compensation for chronic volume overload, with regurgitant fractions of 30-50% in severe disease 5

• Systolic dysfunction: If untreated, left ventricular myocardial contractile dysfunction develops with rapid hemodynamic decline, occurring in 20-30% of patients with untreated mitral valve prolapse 5

Left Atrial and Pulmonary Effects

• Left atrial enlargement: Progressive dilation occurs as the left atrium receives both normal pulmonary venous return and regurgitant volume from the left ventricle, affecting 70-80% of patients with mitral valve prolapse 5

• Pulmonary hypertension: Chronic elevation of left atrial pressure leads to pulmonary venous hypertension, with pulmonary artery systolic pressure >50 mm Hg indicating advanced disease 4

• Pulmonary congestion: Signs of pulmonary edema may be present in severe regurgitation with hemodynamic compromise 1

Critical Clinical Integration

When physical examination shows only a very late soft systolic murmur without diastolic filling sounds and normal chamber findings, severe chronic mitral regurgitation is unlikely even if echocardiography suggests otherwise, as the regurgitation occurs only in very late systole and is frequently overestimated by imaging. 1

Common Pitfalls

• Eccentric jets: When physical examination suggests severe mitral regurgitation but echocardiography shows only mild disease, the echocardiogram likely underestimates severity due to technical limitations with eccentric jets 1

• Overestimation by imaging: When echocardiography suggests severe mitral regurgitation but physical examination shows minimal findings with normal left ventricular and left atrial examination, the echocardiogram likely overestimates severity by not accounting for the short duration of late systolic regurgitation 1

• Positional examination: Failing to examine patients in multiple positions (standing, squatting, supine) may miss mitral valve prolapse entirely 1

Natural History and Prognosis

• Mortality with medical treatment: Yearly mortality rates in patients aged 50 years or older are approximately 3% for moderate organic regurgitation and 6% for severe organic regurgitation 2

• Progressive deterioration: The disease generally progresses insidiously as the heart compensates for increasing regurgitant volume, ultimately leading to left ventricular dysfunction and heart failure if untreated 2

• Irreversible changes: Without timely intervention, unfavorable neurohormonal and structural changes develop that worsen heart failure symptoms, with B-type natriuretic peptide levels increasing 20-50% 5