Multimodal Imaging in Mycobacterium Chimaera Cardiovascular Infections: The Mayo Clinic Experience

Area of Science:

• Cardiovascular Imaging
• Infectious Diseases
• Medical Diagnostics

Background:

• Disseminated Mycobacterium chimaera (MC) infection is a rare but serious complication following cardiac surgery involving cardiopulmonary bypass.
• Contaminated heater-cooler units have been identified as a source of MC transmission.
• Early diagnosis and management are crucial for improving patient outcomes.

Purpose of the Study:

• To review the key features of multimodality cardiovascular imaging in patients with disseminated MC infections.
• To highlight the role of various imaging modalities in the diagnosis and management of MC infection.
• To assess the diagnostic utility of different imaging techniques in identifying cardiac involvement.

Main Methods:

• Retrospective review of 12 patients with confirmed MC infection from January 2010 to April 2021.
• Analysis of electronic medical records focusing on cardiovascular imaging: transthoracic echocardiography, transesophageal echocardiography, cardiac CT, cardiac MRI, and PET-CT.
• Evaluation of imaging findings in relation to MC infection diagnosis.

Main Results:

• Transthoracic echocardiography showed nonspecific abnormalities in most patients, with 27.3% meeting endocarditis criteria.
• Transesophageal echocardiography identified vegetations (36.7%) and aortic root abscess/pseudoaneurysm (27.3%).
• Cardiac CT, MRI, and PET-CT revealed pseudoaneurysms, abscesses, prosthetic ring dehiscence, vegetations, myocarditis, and multiorgan involvement (up to 70% in PET-CT).

Conclusions:

• Multimodality cardiovascular imaging is essential for managing disseminated MC infections, aiding preliminary diagnosis before microbiological confirmation.
• Imaging findings can be subtle and atypical, often not meeting classic Duke's criteria for endocarditis.
• Clinicians need a high index of suspicion and a low threshold for repeat imaging in equivocal cases.