Association of cardiac mechanical dyssynchrony indices with data of dynamic single-photon emission computed tomography of the myocardium: the role of the time interval between the stress test and recording

Abstract

Introduction. According to ECG-synchronized myocardial perfusion imaging (MPI) mechanical dyssynchrony (MD) is a sensitive marker of impaired myocardial perfusion. However, its direct comparison with indicators of myocardial blood flow reserve (MFR) according to single-photon emission computed tomography (SPECT) was not carried out. Traditional MPI protocols imply a long gap between stress test and image acquisition, during which stress-induced changes may pass. It is potentially possible to reduce the time interval down to 5 minutes.Aim: To investigate the relationship between early and delayed MD indices and the data of MFR by means of SPECT.Material and Methods. The study included 20 patients with suspected coronary heart disease, preserved left ventricular ejection fraction (> 55%) and without obstructive coronary artery lesions (< 50%) according to multislice computed coronary angiography. All patients underwent dynamic SPECT (dSPECT) according to a two-day rest/stress protocol. Gated MPI was performed 60 minutes after radiopharmaceutical administration. Myocardial blood flow and reserve, as well as phase histogram standard deviation (PSD, degree) and phase histogram bandwidth (HBW, degree) from 5 minutes after radiopharmaceutical administration were obtained from the dSPECT data by postprocessing. Perfusion data as well as MD indices (PSD, HBW) were obtained from delayed images. Based on dSPECT data, patients were divided into 2 groups: with preserved (MFR ≥ 2.0) and reduced (MFR < 2.0) myocardial blood flow reserve.Results. Correlation analysis showed that MD indices on stress test in early scan had a stronger association with MFR (PSD ρ = –0.68, p < 0.001; HBW ρ = –0.68, p = 0.001) compared to those in delayed scan (PSD ρ = –0.38, p = 0.019; HBW ρ = –0.44, p = 0.005). According to multivariate regression analysis, PSD on stress test at early scan was the only independent predictor of reduced MFR (OR 1.29 (1.1; 1.53)). Stress PSD > 22° obtained at early scanning had a sensitivity of 81% and specificity of 87% (AUC = 0.86, p < 0.001) in predicting of reduced MFR.Conclusion. Left ventricular mechanical dyssynchrony indices obtained by early post-stress gated MPI have a stronger association with myocardial blood flow reserve indices.