Cerebral Thrombus Analysis in Infective Endocarditis: Unveiling Composition for Diagnostic Insight

Background and Aims Infective endocarditis (IE) is a life-threatening condition known to cause stroke. Swift diagnosis and antibiotic treatment are crucial for preventing cerebral and systemic embolism, therefore reducing mortality and morbidity. However, diagnosing IE can be challenging. In this study, we aimed to assess whether analyzing cerebral thrombi retrieved by endovascular thrombectomy from stroke patients with IE could aid in the diagnosis and shed light on the composition signature of endocarditic thrombi. Methods We compared cerebral thrombi from three groups of ischemic stroke patients: those with definite infective endocarditis (IE) (n=10), those with cardioembolic stroke and concomitant infections other than IE (n=10 CE-I+), and those with cardioembolic stroke without infections (n=30 CE-I-). Our multiparameter analysis encompassed histological examinations, molecular biology and microbiological tests to detect microorganisms within the thrombi and to comprehensively assess their structural composition and immune signatures. Results We directly detected invading pathogens through histology or PCR in all cerebral thrombi from IE patients, while none of the control thrombi exhibited such pathogens. Thrombi from IE patients displayed a distinct composition, characterized by a significant lower content of red blood cells, reduced CD14+ monocytes, increased von Willebrand Factor density, and a cell-dominant pattern of Neutrophil Extracellular Traps (NETs) deposition. Conclusions Comprehensive analysis of cerebral thrombi from stroke patients with suspected IE sustains early, definitive endocarditis diagnosis by detecting pathogens and immunothrombotic changes. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement Dr. Strambo received research grant from the University of Lausanne and the Swiss Heart Foundation. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethics committee/IRB of San Raffaele Hospital gave ethical approval for this work I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors