Where is the murmur for mitral regurgitation (MR) best heard?

From the Guidelines

The murmur of mitral regurgitation (MR) is best heard at the cardiac apex (left fifth intercostal space, midclavicular line) with the patient in the left lateral decubitus position. This systolic murmur typically radiates to the left axilla and has a blowing, holosystolic quality. Using the bell of the stethoscope can enhance detection of this murmur. The left lateral position brings the apex closer to the chest wall, making the murmur more audible. Mitral regurgitation produces this characteristic murmur because blood abnormally flows backward from the left ventricle into the left atrium during systole due to incomplete closure of the mitral valve. The location of the murmur corresponds to the anatomical position of the mitral valve and the direction of the regurgitant jet. The intensity of the murmur generally correlates with the severity of regurgitation, though this relationship is not always reliable, particularly in acute MR where a soft murmur may be present despite significant regurgitation.

According to the most recent study 1, accurate diagnosis of both mechanism and severity of MR is crucial for treatment decisions, and imaging techniques such as transthoracic echocardiography, transesophageal echocardiography, and cine magnetic resonance imaging play a significant role in assessing MR. However, the location where the murmur is best heard is not directly addressed in this study, but based on the provided evidence from previous studies 1, the cardiac apex remains the most reliable location for auscultation.

Key points to consider when assessing MR include:

• The murmur's characteristics, such as its timing, pitch, and radiation
• The patient's position, with the left lateral decubitus position being optimal
• The use of the bell of the stethoscope to enhance detection
• The importance of accurate diagnosis for guiding treatment decisions, as emphasized in the most recent study 1.

From the Research

Location for Best Hearing of Mitral Regurgitation Murmur

• The murmur for mitral regurgitation (MR) is best heard at the apex of the heart 2, 3, 4.
• This location is consistent across various studies, including those involving mitral valve prolapse and periprosthetic valvular regurgitation 2, 3, 4.
• In some cases, the murmur may also be audible at the left sternal border 3.

Characteristics of the Murmur

• The murmur is typically a systolic crescendo murmur 2.
• It may be high-pitched and easily audible 3.
• The severity of the murmur can vary, with some cases presenting with a grade 2 or grade 3 murmur 2, 4.

Diagnostic Considerations

• The presence of a systolic murmur at the apex should prompt consideration of mitral regurgitation, especially in patients with a history of mitral valve disease or myocardial infarction 2, 5.
• Echocardiography, including transthoracic and transoesophageal echocardiography, can be useful in confirming the diagnosis and assessing the severity of mitral regurgitation 2, 4, 5.