PAPILLARY MUSCLE RUPTURE AS A COMPLICATION OF ACUTE MYOCARDIAL INFARCTION
Keywords:acute myocardial infarction, mechanical complication, papillary muscle rupture
Papillary muscle rupture is one of the rarest complications, with incidence of 1-5% 1 in patients with acute myocardial infarction (AMI), and usually happens 5-7 days after the initial event.
This complication has a high mortality of 50% in the first 24hours, often leading to decompensation and pulmonary edema. The acute rupture and the severe dysfunction of the mitral leaflet finally result in a severe mitral regurgitation and in most of the cases leads to cardiogenic shock and death. The competence of the mitral valve is maintained by the actions of the anterolateral and posteromedial papillary muscles, but this mechanical complication occurs dominantly on the posteromedial muscle, with greater incidence of more than ten times compared to the anterolateral one.
Transthoracic echocardiography (TTE) is a diagnostic tool with 65-85% sensitivity in visualizing structural abnormalities of the heart and is the most available and fast method in diagnostic this mechanical complication. Beside the structural abnormalities that can be detected, echocardiography can provide precise assessment of the regurgitant jet through the color doppler and continuous doppler ultrasound. It is very important to follow the guidelines from both the European and the American heart associations that recommend urgent echocardiography in patients that become hemodynamically unstable during or after acute myocardial infarction. However, the diagnosis of papillary muscle rupture is not always easy because patients are often elderly and frequently diagnosed with a particularly severe clinical presentation, or hemodynamic instability, which are all factors associated with high operative mortality.
The only definite treatment for this condition is the cardiosurgical treatment, which in the last 10 years has an improved success and reduced mortality2. Intra-aortic balloon counter-pulsation may be necessary for severely unstable patients, or other mechanical circulatory support devices. Mitral valve repair can be done in patients who have a partial papillary muscle rupture, in case of detachment of the main insertion of a head which still remains fixed to the remnant papillary muscle via muscular bridges, unlike the complete rupture (or rupture of the main head) where mitral valve replacement is the main surgical therapy because complete post-MI papillary muscle rupture generally requires MVR due to the friable infarcted tissue. We describe a clinical case of a patient with severe mitral regurgitation after acute myocardial infarction and discuss the management for such patients in the current era.