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Description
A 47-year-old-man with a history of intravenous drug use and recent diagnosis of T-cell lymphoma returned to the emergency department 1 week after initiation of chemotherapy with complaint of left olecranon swelling. Admission vital signs included body temperature of 36.6°C, blood pressure 108/65, heart rate 76 and respiratory rate 18. Physical examination of the left olecranon revealed that it was warm and indurated. An X-ray of the left olecranon and aspiration of the swelling confirmed bursitis. Both the aspiration culture and blood cultures demonstrated methicillin-resistant Staphylococcus aureus. A transthoracic echocardiogram was subsequently performed revealing a large echodensity in the left ventricular apex (figure 1; see online supplementary video 1 and supplementary video 2). The patient refused to undergo a transoesophageal echocardiogram due to its invasive approach. Therefore, a cardiac MRI (CMRI) was obtained to evaluate the lesion. The CMRI demonstrated left ventricular ejection fraction 65%, no valvular vegetations and two linear densities in the left ventricular apex (figure 2). An MRI brain did not reveal any thromboembolic phenomenon. The patient was discharged on intravenous ceftaroline for 6 weeks with follow-up transthoracic echocardiogram after completion of therapy, which demonstrated no intracardiac masses (figure 3; see online supplementary video 3 and supplementary video 4).
Supplementary file 1
Transthoracic echocardiogram—parasternal long view demonstrating large mobile echodensity in left ventricular apex.Supplementary file 2
Transthoracic echocardiogram—apical four-chamber view demonstrating large mobile echodensity in left ventricular apex.Supplementary file 3
Transthoracic echocardiogram—parasternal long view demonstrating no intracardiac mass after completion of intravenous antibiotics.Supplementary file 4
Transthoracic echocardiogram—apical four chambers demonstrating no intracardiac mass after completion of intravenous antibiotics.
Transthoracic echocardiogram in a parasternal long view (A) and apical four chamber view (B) demonstrating a large echodensity in the left ventricular apex (arrows).
Cardiac MRI in coronal view demonstrating two linear densities in the left ventricular apex. The first measuring 1.6×0.3 cm that is mobile (left arrow) and the second measuring 0.5×0.3 cm (right arrow) that is not mobile. There were no valvular vegetations noted.
Transthoracic echocardiogram performed after 6 weeks of intravenous antibiotics in a parasternal long view (A) and apical four chamber view (B) revealing no intracardiac mass present compared with previous imaging.
Primary mural endocarditis is a rare, non-valvular form of endocarditis due to disruption of the endothelial lining of the cardiac chambers.1 Non-valvular endocardial infections are often secondary to valvular vegetations, regurgitation, prosthetic valves and congenital shunts; however, primary mural endocarditis occurs without any cardiac structural abnormalities.1 2 Tahara et al performed a Medline literature search and reported only 19 cases of primary mural endocarditis since 1986.2 Transthoracic and transoesophageal echocardiograms remain the standard of care for prompt diagnosis of this disease process.2 Yet, patients commonly opt against transoesophageal echocardiogram due to invasive approach or sedation requirements. In these cases, CMRI maybe an adequate alternative option for detailed evaluation of cardiac structures. A few low-powered studies have suggested that CMRI is effective at detection of valvular vegetations.3 In addition, the detection of endothelial inflammation on CMRI through delayed enhancement can contribute to diagnosis of non-valvular endocarditis.3 Further randomised, large-scaled studies are required to validate these correlations.
Learning points
Primary mural endocarditis is a rare infection involving non-valvular endocardium due to inflammation and disruption of the endothelial lining of the cardiac chambers without any other cardiac structural abnormalities.1
Risk factors for primary mural endocarditis include immunocompromised state, intravenous drug use and recent surgery. The most common pathogens involved include Staphylococcus aureus, Candida, Streptococcus and Aspergillus.1 2
Though transthoracic and transoesophageal echocardiogram remains the gold standard, initial studies suggest CMRI can be effective as an alternative method to evaluate valvular and non-valvular endocarditis.3
Footnotes
Contributors MP, ZA: involved in diagnosis, patient management, manuscript preparation, literature review. ED, BS: involved in literature review and critical review of manuscript.
Competing interests None declared.
Patient consent Obtained.
Provenance and peer review Not commissioned; externally peer reviewed.