Evaluation On Changes Of Left Atrial Function After Coronary Artery Bypass Grafting Using Two-dimensional Speckle Tracing Imaging And Real-time Three-dimensional Echocardiography

Objective: Two-dimensional speckle tracing imaging（2D-STI）and real-time threedimensional echocardiography（RT-3DE）were used to evaluate the changes of left atrial function after coronary artery bypass grafting（CABG）,in order to evaluate the efficacy of CABG.Methods: Totally 30 patients with multivessel coronary artery disease treated with CABG were enrolled as CABG group.All patients had sinus rhythm,no moderate or severe heart valve disease,congenital heart disease and postoperative heart disease.Another 30 healthy volunteers for the same period were enrolled as control group,all of them were sinus rhythm and were excluded from cardiovascular disease and other systemic diseases affecting cardiac function by comprehensive physical examination and imaging examination.Conventional echocardiography,two-dimensional speckle tracing imaging（2D-STI）and real-time three-dimensional echocardiography（RT-3DE）images were obtained from CABG group before operation,1 month and 3 months after operation and control group,respectively.The parameters of echocardiography were measured.1.The parameters of conventional echocardiographic assessment included: left atrial end-systolic diameter（LAD）.Measurement of left ventricular end-diastolic volume（LVEDV）,left ventricular end-systolic volume（LVESV）and left ventricular ejection fraction（LVEF）by two-dimensional biplane Simpson’s method.The peak velocities of early diastolic E and late diastolic A of mitral valve flow spectrum were measured and the ratio of E/ A were calculated.In tissue Doppler（TDI）mode,the peak velocity of early diastolic e’ of mitral annula was measured,the ratio of E/e’ and△E/e’（the difference between the patients before CABG and 3 months after CABG）were calculated.2.The parameters of 2D-STI assessment included: The curve of left atrial strain during the whole cardiac cycle was obtained,and the values of left atrial strain were measured at each phase,i.e.left atrial reserve strain（εs）,conduit strain（εe）and systolic strain(（εa）.At the same time,the change rate of left atrial strain in patients before CABG and 3 months after CABG were calculated.3.The parameters of RT-3DE assessment included: The curve of left atrial volumetime（VTC）was automatically generated by using 3DQA software.Left atrial maximum volume(LAV_max),left atrial minimum volume(LAV_min)and left atrial pre-systolic volume（LAV_p）were obtained from the curve.Then,left atrial passive ejection fraction（LAPEF）and left atrial active ejection fraction（LAAEF）were calculated.Next,the change rate of left atrial volume in patients before CABG and 3 months after CABG were calculated respectively.Results:1.Conventional echocardiographic assessment LVEDV,LVESV,LVEF,E,A,E/A,e’ showed no significant difference among CABG group before operation,1 month and 3 months after operation and the control group（P>0.05）,whereas LAD and E/e’ were statistically significant（P<0.05）.Compared with the control group,LAD and E/e’ increased significantly in patients before CABG（P<0.05）,while compared with those preoperative,LAD and E/e’decreased 1 month and 3 months after operation（P<0.05）,especially at 3 months after operation（P<0.05）.2.2D-STI assessmentεa showed no significant difference among CABG group before operation,1month and 3 months after operation and the control group（P>0.05）,whereas εs and εe were statistically significant（P<0.05）.Compared with the control group,εs and εe decreased significantly in patients before CABG（P<0.05）,while compared with those preoperative,εs and εe increased 1 month and 3 months after operation（P<0.05）,especially at 3 months after operation（P<0.05）.3.RT-3DE assessment LAAEF showed no significant difference among CABG group before operation,1month and 3 months after operation and the control group（P>0.05）,whereas LAV_max,LAV_min,LAV_p and LAPEF were statistically significant（P<0.05）.Compared with the control group,LAPEF decreases,,LAV_max,LAV_min and LAV_p increased in patients before CABG（P<0.05）,while compared with those preoperative,LAPEF increased,LAV_max,LAV_min and LAV_p decreased 1 month and 3 months after operation（P<0.05）,especially at 3 months after operation（P<0.05）.4.The correlation analysis of left atrial volume,strain rate and E/e’ in patients before and after CABG The rate of changes of LAV_max,LAV_min and LAV_p in patients before CABG and 3months after operation were positively correlated with △E/e’（r=0.608,0.631,0.587,P<0.01）.△E/e’ has the best correlation with the change rate of LAV_min.The rate of changes of left atrium εs,εe in patients before CABG and 3 months after operation were negatively correlated with △E/e’（r=-0.615,-0.637,P<0.01）.△E/e’ has the best correlation with the change rate of εe.Conclusion:1.2D-STI and RT-3DE can be used to quantitatively evaluate the changes of left atrial volume and function in patients after CABG.2.Evaluation on changes of left atrial function after CABG has important clinical value to assess the improvement of myocardial function after surgical revascularization in patients with CHD.