Diagnostic Performance of the FilmArray BCID2 Multiplex PCR Panel Applied to Excised Heart Valve Specimens from Patients with Infective Endocarditis

Infective endocarditis (IE) is a life-threatening disease in which rapid identification of the causative pathogen is essential for appropriate antimicrobial therapy. Although blood cultures remain the standard microbiological method, complementary molecular techniques have the potential to improve pathogen detection in selected clinical settings. This study evaluated the diagnostic performance of the FilmArray Blood Culture Identification 2 (BCID2) multiplex polymerase chain reaction (PCR) panel applied off-label to excised heart valve specimens. Excised heart valve specimens obtained from 47 patients undergoing surgery for IE were analysed using the BCID2 panel. The BCID2 results were compared with blood and valve culture results. Forty-two patients were included for blood cultures and 46 for valve cultures. Using blood culture as the clinical reference method, the BCID2 assay demonstrated a sensitivity of 78.4% (95% confidence interval (CI): 61.8-90.2%), a specificity of 60.0% (95% CI: 14.7-94.7%), a positive predictive value (PPV) of 93.5% (95% CI: 78.6-99.2%), and a negative predictive value (NPV) of 27.3% (95% CI: 6.0-61.0%). Agreement between the BCID2 assay and blood culture was low (Cohen's κ = 0.253; 95% CI: -0.068-0.573; p = 0.067). In the secondary comparison using conventional valve culture, sensitivity was 8.8% (95% CI: 1.9-23.7%), whereas specificity was 100% (95% CI: 75.3-100%). These findings suggest that off-label application of the BCID2 panel to excised heart valve specimens may complement conventional microbiological methods in selected patients with infective endocarditis. However, a negative BCID2 result should not be used to exclude infective endocarditis, and larger multicentre studies are warranted to further evaluate the clinical utility of this approach.