P3362Added value of radiolabeled leukocyte scintigraphy to cardiac device-related infective endocarditis diagnostic criteria
Authors: Holcman K , Malecka B , Zabek A , Szot W , Rubis P , Boczar K , Lesniak-Sobelga A , Hlawaty M , Wisniowska-Smialek S , Stepien A , Podolec P , Kostkiewicz M 
Published: October 2019

Abstract

Background
Radiolabeled leukocyte scintigraphy – hybrid technique of single photon emission tomography and computed tomography with application of technetium99m-hexamethylpropyleneamine oxime-labeled autologous leukocytes (99mTc-HMPAO-SPECT/CT) is an emerging technique in patients with suspected cardiac device-related infective endocarditis (CDRIE).

Purpose
The aim of this prospective study was to assess 99mTc-HMPAO-SPECT/CT added value to modified Duke criteria (mDuke) in CDRIE diagnostic process.

Methods
During the period 2015–2018, we enrolled 103 consecutive patients with suspected CDRIE [70 males (68%), mean age: 61±18 years, mean left ventricle ejection fraction value: 44±17%)]. All patients underwent clinical, microbiologic, echocardiographic evaluation according to ESC guidelines and additionally 99mTc-HMPAO-SPECT/CT (370–740 MBq). Scans were classified as positive in the presence of abnormal tracer uptake involving cardiac and intravascular sections of device electrodes. In the analysis, we added positive 99mTc-HMPAO-SPECT/CT result as an additional major criterion to mDuke classification. Additionally, we compared the diagnostic value of the mDuke classification including 99mTc-HMPAO-SPECT/CT (mDuke-SPET/CT) with the original mDuke classification. The sensitivity and specificity of those two scales were compared with McNemar's test. Diagnostic accuracy was calculated based on final clinical CDRIE diagnosis, including microbiology, echocardiography and 6 month-long follow-up with subsequent outpatient visit.

Results
Overall 58% patients had pacemakers, 25% had implantable cardioverter defibrillators, 16% had resynchronization therapy and 1% had an epicardial lead. Mean time from device implantation was 3.4±3.8 years. Final CDRIE diagnosis was established in 31 (30%) patients. The most common pathogens causing CDRIE were Enterococci (39%) and Staphylococci (35%).
According to the original mDuke classification 16.5% patients had definite CDRIE, 49.5% had possible and in 34% CDRIE was excluded. Overall, 34% of 99mTc-HMPAO-SPECT/CT scans were positive for CDRIE. After reclassification, according to mDuke-SPET/CT the proportion of patients with definite CDRIE increased to 34%, whereas in 37% patients CDRIE was possible and in 29% cases CDRIE was excluded.
Overall, mDuke was characterized with 83% accuracy, 0.52 Cohen's kappa coefficient, 48% sensitivity, 97% specificity, 81% negative predictive value (NPV), 88% positive predictive value (PPV). Whereas mDuke-SPET/CT had 88% accuracy, 0.73 Cohen's kappa coefficient, 87% sensitivity, 89% specificity, 94% NPV, 77% PPV. Compared to mDuke, mDuke-SPET/CT had significantly higher sensitivity (p<0.001).

Conclusions
In patients with suspected CDRIE inclusion of positive radiolabeled leukocyte scintigraphy into modified Duke diagnostic criteria yields significantly higher sensitivity, as well as modest reduction of possible CDRIE diagnoses.

Acknowledgement/Funding
Grant from the Jagiellonian University Medical College (K/DSC/004383)