The Prognostic Value of 99mTc-HMPAO-Labeled Leucocyte SPECT/CT in Cardiac Device-Related Infective Endocarditis

Abstract

Objectives: This was a prospective, single-center study designed to assess the prognostic value of the hybrid technique of single photon emission tomography and computed tomography with the application of technetium⁹⁹m-hexamethylpropyleneamine oxime-labelled autologous leukocytes (⁹⁹mTc-HMPAO-SPECT/CT) in patients with cardiac device-related infective endocarditis (CDRIE).

Background: CDRIE entails the risk of complications and an increase in mortality rates, both in-hospital and long-term. The prognostic value of ⁹⁹mTc-HMPAO-SPECT/CT in the course of CDRIE has not been evaluated so far.

Methods: The project enrolled 103 consecutive patients with suspected CDRIE, all of whom underwent ^99mTc-HMPAO-SPECT/CT. The resulting scans were then classified as positive if the presence of abnormal tracer uptake involving cardiac and intravascular sections of the device electrodes was found. Patients were prospectively observed for a mean time of 17.48 ± 11.9 months. All-cause mortality, in-hospital mortality, and complete hardware removal were assessed, followed by a composite endpoint including complications, namely embolic events, new onset heart failure, uncontrolled infection, renal replacement therapy, reoperation, new heart rhythm, and conduction disturbances.

Results: In the analysis, despite a noticeable trend, all-cause mortality rates were not found to be statistically significantly higher among the 35 patients who registered positive results using ^99mTc-HMPAO-SPECT/CT for CDRIE (group 1) than among the 68 patients from group 2 whose ^99mTc-HMPAO-SPECT/CT results were negative (20% vs. 10.3%, respectively; p = 0.14). However, group 1 did present higher in-hospital mortality (11.4% vs. 0%, respectively; odds ratio: 19.6; 95% confidence interval [CI]: 1.02 to 374.70), an increased rate of complications (43% vs. 9%, respectively; hazard ratio [HR]: 5.9; 95% CI: 2.27 to 15.20), and underwent hardware removal more frequently (57% vs. 16%, respectively; HR: 4.3; 95% CI: 2.07 to 19.08).

Conclusions: In patients with suspected CDRIE, positive ^99mTc-HMPAO-SPECT/CT results were associated with increased rates of in-hospital mortality and complications.

Keywords: (99m)Tc-HMPAO-SPECT/CT; CDRIE; HMPAO; cardiac device-related infective endocarditis; radiolabeled leukocyte scintigraphy.