Correlates of markers of dyssynchrony in patients with STEMI and multivessel disease: an analysis from the IAEA SPECT STEMI trial.

Background: In this substudy of the Value of Gated-SPECT MPI for Ischemia- Guided PCI of non-culprit vessels in STEMI Patients with Multi vessel Disease after primary PCI trial after primary PCI we aim to assess if infarct size affects conventional measures of dyssynchrony at rest. Additionally, we explore if there is an independent correlation of stress-inducible ischemia with dyssynchrony at rest.
Methods: The 48 patients with imaging at randomization were analyzed. Gated-single-photon emission computed tomography (SPECT) MPI with vasodilator stress and technetium-99m-labeled tracers was performed. The phase histogram bandwidth (HBW), phase SD, and entropy were obtained with the QGS software. Correlation between dyssynchrony at rest and infarct size and inducible ischemia was performed using the Spearman test.
Results: According to normal database limits dyssynchrony parameters at rest were abnormal for men. In women only HBW was abnormal. Correlation between the summed rest score with dyssynchrony was significant only for entropy ( P  = 0.035). No correlation was observed for dyssynchrony and stress-induced ischemia.
Conclusion: Entropy, as a measure of dyssynchrony, has potential in the assessment of patients with STEMI and multivessel disease after primary PCI. Smaller residual myocardial scars in PCI-reperfused patients with STEMI may contribute to the lack of correlation between dyssynchrony at rest and infarct size and stress-induced ischemia, respectively.
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