A myocardial abscess is a suppurative infection located in the endocardium or myocardium, that may involve the heart conduction system, valvular apparatus or neighboring structures, most often caused by infective endocarditis or septicemia. This condition is potentially life-threatening, making an early diagnosis and therapy mandatory.
In septic conditions, myocardial abscess symptoms may be concealed by signs of infection of other organs. The presence of a myocardial abscess is suggested by clinical deterioration and abnormal heart rhythm in a patient suspected of infectious endocarditis. This latter entity is associated with new or altered heart murmurs , acute or aggravated chronic heart failure signs and little or no response to antibiotics. Abrupt development of complete or Mobitz II heart block, conduction defects  or severe ventricular arrhythmias strongly suggest a myocardial abscess. This should also be suspected in sepsis along with the development of an acute myocardial infarction or in those with penetrating chest injuries. Most individuals are febrile and have chills and sweats but severely debilitated, chronic kidney disease or elderly individuals may have normal temperature. Additional symptoms include lack of appetite with weight loss, malaise , respiratory symptoms like a cough and dyspnea, general findings like as myalgia, arthralgia, confusion, headache or abdominal pain.
Patients are generally tachycardic and exhibit peripheral endocarditis manifestations: Osler nodes, Roth spots, Janeway lesions, petechiae, splenomegaly, clubbing and embolic events, especially neurologic, renal and pulmonary. If the aortic valve is involved, pulse pressure will be wide because of the valvular regurgitation. Catastrophic heart wall rupture, although infrequent, is possible , as is the presence of multiple, remote abscesses , as opposed to lesions resulting from direct extension from an infected structure, usually valvular .
Blood workup in myocardial abscess should include a complete cell blood count, that will highlight the presence of leukocytosis with granulocytosis and inflammatory, normochromic, normocytic anemia. Serum iron level and iron binding capacity are diminished. Low platelet numbers are possible. A complete chemistry panel is useful in order to determine renal and hepatic status at the moment of presentation. Myocardial abscesses are frequently accompanied by azotemia. Inflammatory markers are increased in most patients, with an erythrocyte sedimentation rate of about 55 mm/h. Blood cultures are indispensable and should optimally be obtained before antibiotic therapy is started. Microscopic hematuria and proteinuria are not infrequent.
Chest radiography is only useful in order to assess pulmonary status and cardiac silhouette, which may serve as an indicator for chronic heart failure. Although it has a low sensitivity, a transthoracic echocardiogram is mandatory in order to evaluate heart morphology especially that of the valves, the presence of regurgitations and contractility. A myocardial abscess, although it may not be visible itself, is suggested by the presence of an echo-free space inside the myocardial mass, rocking of prosthetic valves, septum perivalvular density with a diameter that exceeds 14 mm and aneurysmal dilatation of a Valsalva sinus . Real-time 3-dimensional contrast transthoracic echography offers in some cases a reliable description of the pathological process , as do transesophageal echocardiography , Indium-In 111 leukocyte scintigraphy and magnetic resonance imaging . However, some cases remain undiagnosed until surgery is performed.
The electrocardiogram often offers little information, but in some patients, gradual PR prolongation or new conduction abnormalities have been described. A cardiac catheterization is only employed in cases that are going to be referred for surgery so that coronary artery disease is confirmed or excluded.