Rest-redistribution Thallium-201 Tomography In Assessing The Relationship Between Viable Myocardium And Cardiac Function In Patients With Ischemic Cardiomyopathy

Objective: To investigate the relationship between viable myocardium and cardiac function with rest-redistribution thallium-201 tomography in patients with ischemic cardiomyopathy (ICM).Methods: Fourteen patients with ischemic cardiomyopathy (group ICM) and eight patients with angina pectoris (group AP) were involved in the study from Aug. 2006 to Feb. 2007. Rest-redistribution thallium-201 tomography was performed on all patients. Qualitative and semi-quantitative methods were used to evaluate the characteristics of myocardial blood flow perfusion in both groups. Uptake in each segment was graded on a 4-point scale (0, normal perfusion; 1, mildly decreased; 2, moderately decreased; 3, severely decreased or absent perfusion). Myocardial perfusion defects were defined as followed: reversible defects, part reversible defects and fixed defects. Resting gated myocardial SPECTS with thallium-201 was performed on all the patients also. ECToolbox software was used to measure end systole volume (ESV), end diastole volume (EDV), stroke volume (SV) and left ventricular ejection fraction (LVEF). The relationship between viable myocardium and cardiac function was evaluated by the method of linear regression.Results:All the patients received rest-redistribution thallium-201 tomography without any serious complications. All the patients in group ICM showed abnormal myocardial perfusion tomography (MPT) with moderate or severe perfusion defects distribution. The abnormalities of MPT amount to 112 segments. Most focuses of MPT were reversible or part reversible defects (73 segments). Fixed defects were seen on 39 segments.The myocardial perfusion abnormalities in 14 patients were all multiple segments. All the patients in group AP showed MPT with mild or moderate perfusion defects distribution. The abnormalities of MPT amount to 48 segments. Most focuses of MPT were reversible defects (46 segments). The fixed defects were only seen on 2 segments.The patients'LVEF in group ICM and group AP measured by ECToolbox software was 27.29±6.52%, 61.75±2.36%, respectively. The LVEF in group ICM was positively correlated with the number of viable myocardium segments (r=0.790, p<0.01). However, The LVEF in group AP was negatively correlated with the number of necrosis myocardium (or scar tissue) segments and with myocardial perfusion defect total score (r=-0.667, p<0.05; r=-0.866, p<0.01). The LVEF in group AP was not correlated with the number of viable myocardium segments, necrosis myocardium (or scar tissue) segments and MPT total score (p>0.05, respectively).Conclusions:The characteristic of MPT abnormalities in ischemic cardiomyopathy was broad, irregular, scattered and part reversible or fixed defects. Cardiac function was severely decreased. The amount of myocardial perfusion abnormalities in group ICM is more than that in group AP, the ratio of necrosis myocardium or scar tissue to myocardial perfusion defects in group ICM is significant higher than that in group AP, but the ratio of viable myocardium to myocardial perfusion defects in group ICM is lower than that in group AP.The amount of viable myocardium takes great effect on cardiac function of patients with ischemic cardiomyopathy, while it has no significant effect on cardiac function of patients in group AP. Cardiac function and prognosis of patients with ischemic cardiomyopathy can be evaluated by assessing the level of viable myocardium.That prospectively detect viable myocardium of patients with ischemic cardiomyopathy has important value in performing PCI or CABG therapy, predicting the improvement of cardiac function and assessing the long term prognosis.