The role of stress-induced dyssynchrony obtained from nuclear modalities in evaluation of high-risk patients after surgical treatment of ischemic cardiomyopathy

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Background Mechanical dyssynchrony (MD) is a well-known parameter witch has prognostic value [1]. Stress tests can be used to unmask MD. However, stress-induced changes in left ventricle (LV) MD by data of nuclear imaging modalities are not well-understood, especially its predictive value [2]. Purpose. To assess the role of stress-induced changes of LV MD obtained by nuclear modalities in evaluating high-risk patients after surgical treatment of ischemic cardiomyopathy (ICM). Methods. Sixty-nine patients with ICM were enrolled. Before surgical treatment all patients underwent gated myocardial perfusion imaging (gMPI) (Tc99m-MIBI; 2 days stress-rest protocol, adenosine 140mkg/kg/min) and gated blood pool SPECT (gBPS) (rest – stress, dobutamine doses of 5/10/15 µg/kg/min). After surgical treatment patients were divided into 2 groups: with (n = 21) and without (n = 48) complicated course of early postoperative period (death, intra-aortic balloon pump, extra inotropic support). The following parameters were estimated: summed stress score (SSS), summed rest score (SRS), summed different score (SDS); phase mean, phase standard deviation (PSD) and histogram bandwidth (HBW) (% from cycle for MPI; degrees for gBPS); phase entropy (%, only by gBPS). Stress-induced changes (Δ) were calculated for MPI indices as [stress value-rest value], for gBPS indices as [value on each dobutamine dose-rest value]. For gBPS the maximum changes of MD were calculated as well. Results. Rest gBPS MD correlated with SRS better than rest gMPI (gMPI: PSD r = 0.31, p = 0.005; HBW r = 0.28, p = 0.008; gBPS: PSD r = 0.47, p < 0.001; HBW r = 0.36, p = 0.006; entropy r = 0.39, p = 0.003). Stress gBPS MD correlated better with post stress gMPI MD at the dobutamine dose of 5µg/kg/min. An following increase of the dobutamine dose led to a decrease in the r-value, but it remained significant for all indices (tab.1). Stress-induced MD changes didn’t correlate between gMPI and gBPS. Mann-Whitney test showed significant differences in SDS (p = 0.02) between the groups. Both methods didn’t show any differences at rest study. Stress-induced changes of MD showed differences between groups in only ΔEntropy rest-10µg/kg/min (p = 0.02) and maximum ΔEntropy (p = 0.01) by gBPS, as well as Δphase mean (p = 0.03) by gMPI. Logistic regression analysis showed that only maximum ΔEntropy has prognostic value in prediction of the course of early postoperative period (OR 1.2 95%CI 1.04; 1.37). ROC-analysis showed sensitivity of 80% and specificity of 55% with AUC of 0.7 for cut-off value >0. Conclusion. LVMD obtained from gBPS is associated with SRS better than those obtained from gMPI. Dyssynchrony indices obtained from gMPI with adenosine stress-test have a week to moderate correlation with those obtained from dobutamine gBPS, and correlation decrease with increasing of dobutamine dose. Only maximum ΔEntropy obtained from dobutamine gBPS is associated with the adverse course of early postoperative period in patients with ICM.