The [^99mTc]Tc-HMPAO-labelled white blood cell SPECT/CT as a novel criterion for infective endocarditis diagnosis

Infective endocarditis (IE) poses a significant clinical challenge, necessitating nuanced diagnostic tools for early and accurate detection. The diagnostic role of the hybrid technique of single-photon emission tomography-computed tomography with technetium-99 m-hexamethylpropyleneamine oxime-labelled leukocytes ([^99mTc]Tc-HMPAO-SPECT/CT) has evolved in recent years. This single-center study assessed whether the recent inclusion in the 2023 European Society of Cardiology modified diagnostic criteria of IE (2023 ESC) of infectious lesions detected with [^99mTc]Tc-HMPAO-SPECT/CT affects their diagnostic performance.

Between 2015 and 2019, we enrolled 205 consecutive adults with suspected IE. All participants underwent [^99mTc]Tc-HMPAO-SPECT/CT scans (370-740 MBq). Scans were deemed positive in the presence of intracardiac abnormal tracer uptake and/or within the cardiac implantable electronic device. Patients were prospectively followed-up for 12 ± 10 months. Local device infection (LDI) or IE was diagnosed in 75 (36.6 %) patients, while 72 (35.1 %) [^99mTc]Tc-HMPAO-SPECT/CT results returned positive. Moreover, extracardiac infectious foci were detected in 25 % of [^99mTc]Tc-HMPAO-SPECT/CT scans. The inclusion of both intracardiac and extracardiac lesions detected with [^99mTc]Tc-HMPAO-SPECT/CT yields significantly higher sensitivity (p = 0.003) and negative predictive value (NPV) (p = 0.009).

The inclusion of [^99mTc]Tc-HMPAO-SPECT/CT into the IE diagnostic work-up improves the appropriate classification of patients. For patients with IE, the extended inclusion of lesions detected with [^99mTc]Tc-HMPAO-SPECT/CT in the ESC 2023 diagnostic criteria significantly improves sensitivity and NPV while reducing potential IE misdiagnoses. This pioneering imaging modality is poised to become an integral component of clinical practice, promising to advance IE diagnosis and management.