Assessment Of Left Atrial Function In Patients With Myocardial Infarction Before And After PCI By Left Atrial Volume Tracking Technique

BackgroundMyocardial infarction (MI) does serious harm to human health and is one of the fatal diseases. Along with the change of people’s life style and the improvement of living standard, incidence of MI is rising currently at home and abroad, therefore, how to treat MI effectively has always been the focus of clinical researches. Recently percutaneous coronary intervention (PCI) has become the first choice in the treatment of MI in conditional medical institutions. Studies have shown that PCI can reduce mortality, complications and preserve left ventricular function. But the effect of PCI on left atrial function is still not clear.Left atrial volume tracking technique (LAVT) is a new ultrasound technique developed in recent years, it can reflect the changes of the left atrial function intuitively. Many domestic and international researches have applied LAVT to study the left atrial function in diabetes, hypertension, atrial fibrillation and so on. And these studies have gained clinical acceptance. So far, there are no related reports about using LAVT to evaluate the left atrial function of MI. This study is to assess the left atrial function by applying LAVT, and to further clarify the therapeutic advantage of PCI in MI. At the same time, the left atrium’s physiological function is closely related to the left ventricular diastolic filling process, and normal left atrial hemodynamic is essential to maintain the left ventricular function. Therefore, from studying the left atrial function after PCI, we can further validate the effects of PCI on the left ventricular diastolic function.Tei index is a comprehensive evaluation of cardiac systolic and diastolic function. The reliability of Tei index has been proved through practice for many years. At present, reports about the correlation between left atrial function and global cardiac function is rare. Thus, this study was to explore the correlation between left atrial function and cardiac function combined with Tei index, and to evaluate the function and significance of applying LAVT for clinical work.Purposes1. To evaluate the left atrial function in patients with MI by LAVT.2. To evaluate the changes of the left atrial function in patients with MI after PCI.3. To study the correlation between the left atrial function and cardiac function.Objectives and Methods1. ObjectivesThe first part was consisted of45cases of patients with myocardial infarction:38males and7females,the mean age was62.91±6.00.Among all the patients, there were10cases with extensive anterior wall myocardial infarction,12cases with anterior wall myocardial infarction,15cases with inferior wall myocardial infarction,8cases with lateral wall myocardial infarction. All of the patients were in sinus rhythm, and underwent conventional electrocardiogram, echocardiography, coronary angiography and myocardial enzymology check, to exclude hypertension, diabetes mellitus, congenital heart disease, cardiomyopathy, severe arrhythmias and severe valvular lesions. During hospitalization all the patients were treated with PCI, and after PCI, the forward flow returned back to TIMI3.Each case was followed up three months later.40normal subjects without obvious diseases were classified in the control group, and they were measured in the same way as that of the first part. There were no significant differences in age or sex ratio between the two groups (P>0.05)2. Research method HI VISION Preirus color doppler imaging instruments with s50A probe and2.0-4.0MHz frequency was used. The apparatus is configured with LAVT technique and related post-processing software. Each study object underwent routine2-dimensional echocardiography check, collect and store apical four-chamber and two-chamber dynamic images in three heartbeat cycles. Left atrial endocardial surface should be displayed as clear as possible in image acquisition process. Video was saved for offline analysis. LVEF was measured by two-plane Simpson’s method, Tei index was measured by Dual Doppler Modality.3. Image processingOpening the video, and running LAVT software, we could get the left atrial volume-time curve and rate of volume change curve. From the data of the left atrial volume-time curve, we could know the left atrial maximal volume (LAVmax), left atrial minimal volume(LAVmin).From the left atrial volume change rate curve, we derived the left atrial filling rate in systolic phase (dv/dtS),the left atrial emptying rate in early diastolic phase(dv/dtE) and the left atrial late diastolic emptying rate in early diastolic phase (dv/dtA). Then explored the correlation between Tei index and dv/dtA.Results1. Compared with the control group, LAVmax, LAVmin ascended apparently and the dv/dtS, dv/dtE, LVEF descended significantly (all P<0.05).There were no significant differences in dv/dtA (P>0.05) between the control group and patients with MI before PCI.2. Compared with preoperative group, dv/dtS, dv/dtE, dv/dtA, LVEF ascended significantly and LAVmax, LAVmin descended significantly (all P<0.05) in MI3month after PCI (all P<0.05).3. Compared with the control group, the dv/dtS, dv/dtE and Tei index descended significantly and dv/dtA, LAVmax and LAVmin ascended apparently in patients with MI3month after PCI (all P<0.05), and there was no difference in LVEF between the two group(P>0.05).4. Among the parameters of the control group and patients with MI3month after PCI,Tei index was positively related to dv/dtA(rc=0.81,rpci=0.66),however,there was no obvious correlation between Tei index and dv/dtA before PCI. Conclusions1. After acute myocardial infarction, left atrial storage, pipeline function are significantly lower than the control group, There are no apparent change in left atrial pump function.LAVmax and LAVmin become larger.2. After PCI, compared with preoperation, the left atrium’s three physiological functions recover gradually, LAVmax, LAVmin become smaller. But compared with the control group, left atrial storage and pipeline function decline, and the auxiliary pump function enhances. LAVmax and LAVmin increase.3. Among the parameters of the control group and patients with MI3month after PCI, global cardiac function is positively related to left atrial pump function, however, there is no obvious correlation between Tei index and dv/dtA before PCI.4. PCI technique can effectively improve left ventricular systolic dysfunction in patients with the MI, but left atrial function could not be completely reversed.5. Being a technique of measuring the function of the left atrium in patients with MI, LAVT technique is one of the most important tools to evaluate the treatment effect after PCI.