Myocardial Rupture 

Myocardial rupture occurs in the setting of acute myocardial infarction (AMI), blunt and penetrating cardiac trauma (see image below), primary cardiac infection, primary and secondary cardiac tumors, infiltrative diseases of the heart, and aortic dissection. The clinical presentation of myocardial rupture depends on the mechanism and site of injury and the hemodynamic effects of the rupture. Mortality rates are extremely high unless early diagnosis and surgical intervention are provided rapidly.

See the image below.

AMI is the most common etiology of myocardial rupture. Ischemic myocardial rupture may involve the left ventricular (LV) and right ventricular (RV) free walls, ventricular septum, and LV papillary muscle, in decreasing order of frequency. Myocardial rupture rarely involves the left or right atrial walls.

The consequences of myocardial rupture in the setting of AMI can include pericardial tamponade, ventricular septal defect (VSD) with left-to-right shunt, acute mitral regurgitation (MR), or formation of a pseudoaneurysm. In most instances, the catastrophic clinical presentation occurs within 3-5 days of a rather small AMI. Both hemodynamic factors (increased intracavitary pressure) and regional myocardial structural weakness (myocyte necrosis, collagen matrix resolution, intense inflammation) are important contributory factors to myocardial rupture in the setting of AMI.

In rare instances, patients have been reported to simultaneously experience LV free wall rupture and ventricular septal or papillary muscle rupture (double rupture) following AMI. In the case of a papillary muscle rupture, the posteromedial papillary muscle is twice as likely to rupture as is the anterolateral papillary muscle. This likelihood is because the anteromedial papillary muscle is more often supplied by 2 arterial systems (left anterior descending and left circumflex coronary arteries), whereas the posteromedial papillary muscle is frequently supplied by only one coronary artery (usually the right) system. Rupture of both papillary muscles following AMI has been reported.

In some patients who survive LV free wall rupture following AMI, the rupture can be sealed by the epicardium (visceral pericardium) or by a hematoma on the epicardial surface of the heart. This entity has been referred to as LV diverticulum or contained myocardial rupture and represents a subacute pathologic condition between free rupture into the pericardial cavity and formation of a pseudoaneurysm. A pseudoaneurysm is formed if the area of rupture is contained locally by the adjacent parietal pericardium and represents the chronic stage of LV free wall rupture. The most common etiology of LV pseudoaneurysm is AMI. (LV pseudoaneurysm is twice as common with inferior, rather than anterior, AMI.) LV pseudoaneurysms may develop following surgery, especially following mitral valve replacement.

Blunt cardiac trauma, most commonly in the setting of an automobile accident, may cause myocardial rupture as a result of cardiac compression between the sternum and the spine, direct impact (sternal trauma), or from deceleration injury. It may result in rupture of the papillary muscles, cardiac free wall, or the ventricular septum. The cardiac chambers involved are, in decreasing order of frequency, the right ventricle, left ventricle, right atrium, and left atrium.

However, among those who reach the hospital alive, the right atrium is the most commonly involved chamber. In up to 30% of cases, the rupture involves more than one chamber. Delayed myocardial rupture has been reported as a result of cardiac contusion. Acute mitral or tricuspid regurgitation, VSD, or pericardial tamponade may result from myocardial rupture secondary to blunt cardiac trauma.

Penetrating myocardial injury occurs most commonly as a result of stab or gunshot wounds, as shown below. Unlike blunt trauma, penetrating cardiac injury always involves the pericardium. Consequently, ventricular free-wall rupture in this setting may result in either pericardial tamponade (if the pericardial wound is obliterated) or intrathoracic hemorrhage. While pericardial tamponade is more common with stab wounds, gunshot wounds more frequently are associated with hypovolemic shock. The cardiac chambers involved are, in decreasing order of frequency, the right ventricle, left ventricle, right atrium, and left atrium. See the image below.

Myocardial abscesses accompanying infective endocarditis may rupture transmurally, resulting in VSD or pericardial tamponade (pyohemopericardium). Such abscesses are observed most commonly in the setting of Staphylococcus aureus endocarditis involving prosthetic valves in the aortic position. Rarely, myocardial necrosis due to acute myocarditis, tuberculosis, or sarcoidosis may result in myocardial rupture.

Myocardial rupture is rarely caused by primary (hemangiopericytoma, angiosarcoma, lymphoma) or secondary (metastatic) cardiac tumors. Lymphomas and acute myeloblastic leukemia also have been associated with myocardial rupture.

Frequency

United States

Myocardial rupture complicates up to 10% of AMIs. Approximately 6-10% of penetrating chest wounds and 15-75% of blunt chest traumas are associated with cardiac injury. Myocardial rupture occurs in 10-15% of fatal motor vehicle accidents. Incidence of cardiac rupture following blunt trauma is 0.5-2% among hospital trauma admissions.

Mortality/Morbidity

Myocardial rupture is responsible for nearly 15% of all in-hospital deaths among patients with AMI. It is the second most common cause, after pump failure, of in-hospital mortality among patients with AMI.

The overall mortality rate from myocardial rupture following blunt trauma is 76-93%. However, among those who reach the hospital alive, the mortality rate is 29-50%. Mortality from myocardial rupture resulting from penetrating trauma ranges from 62-89% in the field to 2-83% after reaching a hospital. The latter largely depends on the type of injury, rapidity of the transfer to a hospital, and patients' vital signs and condition upon arrival.

Following myocardial rupture as a result of penetrating cardiac trauma, hospital mortality is higher in those presenting with hypovolemia rather than pericardial tamponade (22% vs 8%). In-hospital mortality is lowest for patients with RV rupture.

Sex

Myocardial rupture after AMI is reported more commonly in women than in men (1.4:1).

Traumatic myocardial rupture is more common in males (up to 85% in some series) than in females.

Age

Myocardial rupture after AMI is more common in patients aged 60 years or older.

Traumatic myocardial rupture is observed more commonly in those aged 15-63 years (mean, 34 y).^[1]