Abstract
Background: The role of Technetium-99 m (Tc-99m) labeled tracers has been discussed for the detection of viable myocardium. One of the methods that is considered to be used in the diagnosis of viability is gated Myocardial Perfusion Imaging (gMPI) conducted under the influence of Beta Blocker Drugs (BBD).
Objective: The aim of this study is twofold: First, to evaluate the role of the Beta Blocker Drugs (BBD) on fixed perfusion defects on gated Myocardial Perfusion Imaging (gMPI) (myocardial viability) and second, to assess the role of BBD on the functional parameters of the left ventricle.
Methods: 31 patients (28 men, 3 women) who were on BBD treatment and had fixed perfusion defects on their gMPI and submitted to fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) were prospectively enrolled to the study. One week after the completion of the stress-rest gMPI, rest gMPI was repeated for each patient while they were on BBD treatment. All systolic and diastolic functional measurements, perfusion defect extent and size were obtained during both rest gMPI studies with and without BBD. The parameters derived from FDG PET/CT were compared to those that were derived from gMPI without BBD.
Results: A statistically significant difference between the scores of both groups was not observed, except the Time to Peak Filling Rate (TTPFR). End-systolic/diastolic volumes derived from gated FDG PET/CT were significantly lower than the ones derived from the gMPI presumably due to higher spatial resolution of the FDG PET/CT while the study did not reveal a statistically significant difference between the ejection fraction values.
Conclusion: According to our results, metoprolol does not seem to change functional parameters of the left ventricle that were detected by gMPI except TTPFR. Besides, it seems that metoprolol does not affect the size of the perfusion defect, and therefore, it does not have a role to demonstrate the presence of viability that was confirmed via FDG PET/CT.
Keywords: Beta blocker, 18F FDG PET/CT, gated myocardial perfusion imaging, fixed perfusion defect, metoprolol, viability.
Graphical Abstract
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