Relative contribution of imaging techniques for the contemporary diagnosis of infective endocarditis: a single-center experience

Abstract Introduction In developed countries, the incidence of infective endocarditis (IE) is up to 6 cases per 100,000 individuals and in-hospital mortality rates are reported to reach 30%. The diagnostic recommendations for IE have been revised in the new ESC guidelines emphasizing the use of transesophageal echocardiography (TEE) and advanced imaging techniques (computed tomography [CT], magnetic resonance [MR], positron emission tomography [PET] and white blood cell scintigraphy [WBC-SPECT]). Aims This research aims to investigate the practical applicability of established clinical guidelines in a real-world population with suspected IE. Methods We reviewed the hospital database from 06/2021 to 06/2023 using the international classification of disease codification (ICD-10) for IE. Only patients admitted to Cardiology or Cardiac Surgery departments were included. Diagnosis of IE was defined according to the modified Duke criteria. Firstly, we identified individuals in whom diagnosis was performed by clinical presentation, blood cultures and transthoracic echocardiogram (TTE). Subsequently, we identified those who required further imaging diagnostic investigation. Results A total of 63 patients were included [mean age 64 ±14 years; 76% male (n=48)]. Native IE was diagnosed in 53 (84%) patients, prosthetic IE in 7 (11%) and cardiac implantable electronic devices-related IE in 3 (5%). A total of 26 (41%) patients had at least one predisposing risk factor, 48 (76%) presented with fever, 24 (38%) suffered an embolic event and 1 (2%) had an immunological phenomenon. Out of 49 positive blood cultures (78%), typical microorganisms consistent with IE were isolated in 25 (78%) of samples: 13 (34%) staphylococcus aureus, 10 (26%) oral streptococci, 9 (24%) enterococcus faecalis, 5 (13%) streptococcus gallolyticus and 1 (3%) HACEK group. Overall, in 22 (34%) patients, a definitive diagnosis of IE was established by means of clinical presentation, blood cultures and TTE. In the remaining, TEE was performed in 86% (n=36). Of those, a definite diagnosis was established in 52% (n=22). Brain and whole-body imaging upgraded the diagnosis from possible to definite in 3 (5%) patients. In the one patient in which a comprehensive clinical evaluation including TTE and TEE rejected IE, the diagnosis was ultimately established by means of PET. The median time from admission to the definite/possible diagnosis of IE was 6 (IQR 2-17) days. A total of 47 (75%) patients underwent surgery, with the most frequent indications being heart failure 46% (n=21) and uncontrolled infection 28% (n=13). Time from diagnosis to surgery was 10 (2-19) days, hospital length of stay was 45 (35-70) days and in-hospital mortality 21%. Conclusion Clinical presentation, blood cultures and TTE plus TEE established the definite or possible diagnosis of IE in most patients with suspected IE. Advanced imaging techniques allowed the establishment of definite diagnosis in only 6% of patients.