In a 45‑year‑old patient with an acute holosystolic murmur heard at the apex and radiating to the axilla, what are the most likely etiologies and what immediate diagnostic and therapeutic steps are indicated?

Acute Holosystolic Murmur in a 45-Year-Old

In a 45-year-old patient presenting with an acute holosystolic murmur at the apex radiating to the axilla, acute severe mitral regurgitation is the most likely diagnosis and requires urgent echocardiography followed by hemodynamic stabilization and early surgical intervention to prevent mortality from cardiogenic shock and pulmonary edema. 1

Most Likely Etiologies

The acute presentation with a holosystolic apical murmur radiating to the axilla in this age group most commonly results from:

• Chordae tendineae rupture (most common cause today, typically in patients with degenerative mitral valve disease or mitral valve prolapse) 2, 3
• Papillary muscle rupture (associated with acute myocardial infarction, particularly inferior MI, though incidence has declined with modern percutaneous revascularization) 1, 2
• Infective endocarditis causing leaflet perforation or chordal rupture 1, 2
• Spontaneous chordal rupture in degenerative valve disease 1

Critical Diagnostic Pitfalls

The murmur may be deceptively soft or even absent despite severe regurgitation because the rapid rise in left atrial pressure with concomitant fall in LV systolic pressure limits the pressure gradient to early systole, making the murmur short and unimpressive or inaudible. 1 This is a dangerous trap—absence of a loud murmur does NOT exclude severe acute MR. 1

Immediate Diagnostic Steps

Transthoracic Echocardiography (First-Line)

Perform urgent TTE immediately to assess: 1

• Mechanism of MR: Look specifically for flail leaflet (triangular mobile structure prolapsing into left atrium), ruptured chordae, or vegetations 1
• LV function: Expect hyperdynamic (not depressed) LV function—this distinguishes acute MR from other causes of acute decompensation 1
• Hemodynamic severity: Assess pulmonary artery pressures, RV function, and degree of regurgitation 1

Transesophageal Echocardiography (When TTE Inadequate)

Proceed immediately to TEE if: 1

• TTE is nondiagnostic but clinical suspicion remains high
• Narrow eccentric jets are difficult to visualize on TTE
• Patient has tachycardia or hemodynamic instability after MI with hyperdynamic LV and no other explanation
• Need to detect vegetations, annular abscesses, or precise anatomic details for surgical planning 1

TEE is particularly crucial because TTE may underestimate lesion severity by inadequate imaging of eccentric color flow jets. 1

Additional Urgent Testing

• ECG and cardiac biomarkers: Rule out acute MI as precipitant of papillary muscle rupture 2
• Blood cultures: If endocarditis suspected, obtain before antibiotics 1
• Coronary angiography: Perform urgently if AMI suspected to define anatomy and need for revascularization 2

Immediate Therapeutic Management

Hemodynamic Stabilization (Bridge to Surgery)

For normotensive patients: 1

• Sodium nitroprusside (or nicardipine) reduces afterload, preferentially directing flow away from the regurgitant pathway into the aorta, thereby decreasing MR while increasing forward output 1
• Titrate carefully to avoid hypotension 1

For hypotensive patients: 1

• Combination therapy: Dobutamine (inotropic support) PLUS nitroprusside 1
• Intra-aortic balloon counterpulsation: Use to stabilize patients with severe reduction in forward output—increases forward output and mean arterial pressure while diminishing regurgitant volume and LV filling pressure 1

Critical limitation: Vasodilator therapy is often limited by systemic hypotension that worsens when peripheral resistance is decreased. 1

Definitive Treatment

Early surgical intervention is typically required because acute severe MR causes: 1, 2

• Sudden volume overload on unprepared left atrium and ventricle
• Large v waves causing pulmonary congestion and edema
• Reduced forward cardiac output leading to shock
• Both pulmonary congestion AND cardiogenic shock simultaneously 1

If infective endocarditis is confirmed, initiate appropriate antibiotics immediately and consider early surgery (antibiotic therapy plus early surgical intervention). 1

For high surgical risk patients in emergency situations, percutaneous mitral valve edge-to-edge repair is an alternative therapeutic option. 4

Key Clinical Pearls

• Physical examination may be misleading: Normal-sized LV produces no hyperdynamic apical impulse; systolic murmur may not be holosystolic or may be absent; third heart sound or early diastolic flow rumble may be the only abnormal finding 1
• Hyperdynamic LV function on echo in acute heart failure should immediately raise suspicion for severe acute MR 1
• Murmur radiation pattern provides anatomic clues: Anterior leaflet flail radiates to axilla/infrascapular area; posterior leaflet flail radiates anteriorly and mimics aortic stenosis 1
• Time is critical: Medical therapy has limited role and is aimed primarily at stabilizing hemodynamics in preparation for surgery 1