Understanding Post-MI Papillary Muscle Rupture
A 70 year old female presents for shortness of breath. She has a past medical history of HTN, HLD, DM, and is a current everyday smoker. The patient came to the ED with back pain three days ago and was discharged with a muscle relaxer. Her back pain resolved, but today she suddenly became short of breath one hour prior to presentation. She denies any other symptoms.
Her vitals show a BP of 110/70, HR 120, RR 30, Temp 36, SpO2 90%. She is in moderate respiratory distress, speaking in three word phrases, and using her accessory muscles. Her lung exam demonstrates diffuse crackles bilaterally. Cardiac exam demonstrates a holosystolic murmur best heard at the apex. She has no pitting edema. The rest of the physical exam is unremarkable.
You order a full cardiac work-up and place the patient on BiPAP. Bedside ultrasound shows B lines diffusely and a hyperdynamic heart. On the 4 chamber view you notice that one of the leaflets of the mitral valve is not moving. You select color doppler on the ultrasound and realize that there is severe mitral regurgitation. You immediately call the cardiology fellow and place a cardiothoracic surgery consult with the concern for papillary muscle rupture. The EKG shows V1 to V4 ST depressions most pronounced in V2. You request activation of the cath lab. The patient is taken to the cath lab for a successful PCI. She is subsequently taken to the OR with cardiothoracic surgery for replacement of the mitral valve.
Take Away #1:
Presentation: Papillary muscle rupture most often occurs 2 to 7 days after an MI. Patients can present with acute respiratory distress and cardiogenic shock. The clinical course is unpredictable. Early diagnosis and surgical repair is crucial for good outcomes.
Echocardiogram: The gold standard test for the diagnosis is transesophageal echocardiogram (TEE). Transthoracic echocardiogram (TTE) is also adequate but sometimes it is difficult to see the affected leaflet of mitral valve because it’s too posterior. TEE can capture this view and therefore has better sensitivity. However TTE has good sensitivity for severe mitral regurgitation. Therefore, together with the whole clinical picture, using the ultrasound at the bedside essential.
Take Away #2:
Two papillary muscles are responsible for the function of the mitral valve:
Anterolateral papillary muscle which typically has dual supply (left anterior descending and left circumflex)
Posteromedial papillary muscle which is supplied by the posterior descending artery. The posteromedial papillary muscle is more frequently ruptured compared to the anterolateral papillary muscle.
The most common cause is an infarction upstream to the posterior descending coronary artery. You do not need a massive MI in order to cause rupture of the papillary muscles. Even a single occlusion of the obtuse or diagonal arteries can be enough.
Take Away #3:
Treatment of ruptured papillary muscle often necessitates surgical repair. If it cannot be repaired, the mitral valve is replaced. Usually coronary revascularization is done prior to surgical repair. Without surgical repair, 90% of patients will die within one week.
Other causes of papillary muscle rupture:
Any heart surgery
Other catastrophic mechanical complications of MIs:
Free wall rupture
Interventricular septum rupture
Together with papillary muscle rupture, these are a result of structural integrity of infarcted tissue. Thanks to early revascularization therapy, these complications are rare, about 2 to 3% of complications from MIs.
Philip Siva Vittozzi Wong, MD is a current third year resident at Stony Brook Emergency Medicine.
Jain SK, Larsen TR, Darda S, Saba S, David S. A forgotten devil; Rupture of mitral valve papillary muscle. Am J Case Rep. 2013;14:38–42.
Ternus BW, Mankad S, Edwards WD, Mankad R. Clinical presentation and echocardiographic diagnosis of postinfarction papillary muscle rupture: A review of 22 cases. Echocardiography. 2017 Jul;34(7):973-977.
Edited by Bassam Zahid, MD