Papillary muscle rupture

Papillary muscle rupture (PMR) is a dangerous complication that can evolve as a consequence of myocardial infarction or infective endocarditis leading to severe acute mitral or tricuspid regurgitation leading to left or right-sided heart failure.

Epidemiology

Papillary muscle rupture is rare and frequency is estimated in 0.5-5% of myocardial infarctions. It is more common in first-time coronary events and can be also seen in smaller infarctions ^1-4.

Associations

Papillary muscle rupture is associated with the following conditions:

• acute severe mitral regurgitation or less often tricuspid regurgitation
• acute left or right ventricular dysfunction

Clinical presentation

Signs and symptoms are subject to the affected valve. As for left ventricular papillary muscle rupture patients usually present with symptoms of acute heart failure including severe dyspnea, orthopnea and hypoxia in the immediate post-myocardial infarction period up to one week ¹. Chest pain and hypotension and other signs of cardiogenic shock are further symptoms ^1-4.

Complications

Complications of papillary muscle rupture ^1-4:

• acute heart failure
• cardiogenic shock
• cardiac arrest
• sudden cardiac death

Pathology

Rupture of a papillary muscle can be complete affecting the trunk that supports half of the chordae tendineae to both mitral valve leaflets or partial, affecting one or more of several muscle heads ¹.  

Etiology

Causes of papillary muscle rupture include the following ^1-5:

• myocardial infarction
• infective endocarditis
• blunt chest trauma
• Takotsubo cardiomyopathy
• coronary vasospasm
• iatrogenic

Location

Five papillary muscles in the heart can potentially be affected: the anterolateral and posteromedial papillary muscles in the left ventricle ^1-5, which attach to the mitral valve and three papillary muscles attaching to the tricuspid valve.

The posteromedial papillary muscle complex of the left ventricle seems to be the most frequently affected ^1-4, typically in the setting of precedent myocardial infarction with the involvement of the posterior descending artery ¹.

Radiographic features

Echocardiography

Transthoracic or transesophageal echocardiography is considered is usually a first-line imaging modality for the evaluation of mitral valvular disorders. Findings include the following ²:

• mitral or tricuspid regurgitation
• flail leaflet or bi-leaflet prolapse
• ruptured papillary muscle head with detachment
• mobile masses attached to the chordae tendineae

MRI

Patients with a complete papillary muscle rupture will probably rarely undergo cardiac MRI due to hemodynamic instability. However, MRI can demonstrate the rupture with myocardial edema and signs of myocardial infarction or myocardial injury of the papillary muscle and the adjacent myocardium including the following ¹:

• cine imaging
  • mitral or tricuspid regurgitation with increased leaflet mobility or flail leaflet
  • regional wall motion abnormalities
  • ruptured papillary muscle head or mobile mass attached to the chordae tendineae
• T2/STIR black blood: hyperintensity of the affected papillary muscle and adjacent wall
• IRGE/PSIR: late gadolinium enhancement demonstrating myocardial injury

Radiology report

The radiological report should include a description of the following features ¹:

• affected papillary muscle including the extent
• flail leaflet or prolapse
• valvular regurgitation
• atrial dilatation
• cardiac volumes and measurements
• associated myocardial infarction/myocardial injury

Treatment and prognosis

Prognosis of left ventricular papillary muscle rupture without surgical treatment is poor with a high mortality rate especially in the case of complete rupture. Initial medical therapy includes oxygen therapy, vasodilator therapy, diuretics and afterload reduction. Intra-aortic balloon counterpulsation might be also helpful.

Surgical management consists of mitral valve repair or mitral valve replacement with coronary artery bypass grafting ^1-6.

History and etymology

Papillary muscle rupture was first described by Merat in 1803 in a post mortem examination and by S. Davison in 1948 on antemortem ^2,7.

Differential diagnosis

Conditions mimicking the imaging the clinical presentation and imaging appearance of papillary muscle rupture include:

• mitral valve prolapse
• chordae tendineae rupture
• chronic mitral regurgitation