What type of murmur is most commonly associated with mitral regurgitation?

Mitral Regurgitation Murmur Characteristics

Mitral regurgitation most commonly presents as a holosystolic (pansystolic) murmur that begins with S1 and continues through systole until S2, representing continuous regurgitant flow throughout ventricular contraction. 1

Murmur Timing Variants

The timing of the systolic murmur in mitral regurgitation provides critical diagnostic information about the underlying pathophysiology:

Holosystolic (Pansystolic) Murmur

• This is the classic presentation of chronic mitral regurgitation, beginning with the first heart sound and continuing through systole until the second heart sound 2, 1
• Indicates an established pressure gradient between the left ventricle and left atrium throughout ventricular contraction 1
• Represents the most common pattern in chronic, hemodynamically significant mitral regurgitation 2

Late Systolic Murmur

• Begins well after ejection and ends before or at S2 2, 1
• Characteristically associated with mitral valve prolapse, with or without midsystolic clicks 2, 1
• Results from late systolic regurgitation due to prolapse of the mitral leaflet(s) into the left atrium 2
• Soft or moderately loud, high-pitched murmurs best heard at the left ventricular apex 2

Early Systolic Murmur

• Begins with S1 but ends in midsystole 2, 1
• Occurs in acute mitral regurgitation, such as papillary muscle rupture or acute chordal rupture 1
• Less loud and more frequently localized than pansystolic murmurs 3
• Associated with un-enlarged left ventricles in the majority of cases (12 of 15 patients in one series) 3

Midsystolic Murmur

• Can occur with functional mitral regurgitation 2, 1
• Requires echocardiography to distinguish from benign flow murmurs or aortic stenosis 2, 1

Critical Clinical Pitfall: Silent Mitral Regurgitation

In 39% of patients with angiographically confirmed mitral regurgitation, no murmur may be audible 4. This "silent" severe mitral regurgitation represents a potentially reversible cause of refractory heart failure 5. If the murmur is not audible after listening in multiple positions or with dynamic maneuvers, or is limited to late systole only, severe mitral regurgitation is less likely—but cannot be excluded 2.

Murmur Radiation Patterns

The direction of murmur radiation provides clues to the underlying leaflet pathology in primary mitral regurgitation:

• Anterior leaflet flail: Murmur radiates to the axilla and left infrascapular area 2
• Posterior leaflet flail: Murmur radiates anteriorly and can be confused with systolic ejection murmurs 2
• Secondary mitral regurgitation: Murmur is usually best heard at the apex and radiates to the axilla 2

Dynamic Maneuvers to Enhance Detection

Handgrip Exercise

• Increases mitral regurgitation murmur intensity by increasing afterload 2, 1
• Useful for distinguishing mitral regurgitation from other systolic murmurs 2

Respiratory Variation

• Left-sided murmurs (including mitral regurgitation) are louder during expiration 2, 1

Positional Changes

• Standing diminishes most murmurs except hypertrophic cardiomyopathy and mitral valve prolapse, which lengthen and intensify 2, 1
• Squatting makes most murmurs louder, but those of hypertrophic cardiomyopathy and mitral valve prolapse usually soften 2

Associated Physical Findings

In patients with primary mitral regurgitation:

• The presence of a diastolic filling complex (S3 plus short diastolic murmur) is usually associated with significant regurgitant volume and severe mitral regurgitation 2
• One or more non-ejection clicks may be audible 2
• Atrial fibrillation or other arrhythmias may be present and can complicate the examination, particularly when the heart rate is rapid 2

When to Obtain Urgent Echocardiography

Urgent echocardiography is required for any new systolic murmur with acute heart failure, hypotension, or shock, and for unexplained heart failure with normal left ventricular function on clinical assessment 1. This is particularly important given that severe mitral regurgitation can be hemodynamically critical yet silent on auscultation 5.