| Objective:Left atrial size and function play an important role in preventing the risk of cardiovascular events, mortality and prognosis. Assessment of left atrium volume and function by real-time three-plane quantitative tissue velocity imaging(QTVI) and strain rate imaging (SRI) to measure left atrial various indexes, which reflect left ventricular diastolic function, investigate the feasibility of the real-time tri-plane strain rate imaging for assessment of left atrial function of acute ST segment elevation myocardial infarction.Methods:30 consecutive patients were quantified diagnosis of ST-segment elevation AMI treated with primary percutaneous coronary intervention in the First Affiliated Hospital of Kunming Medical University were selected from August,2015 to February,2016. Male 19,Female 12,average age 57.2+8.1 years. The antero-posterior dimension of the left atrium (LA-ap) was obtained from the parasternal long-axis view and measured distal to the aortic sinus and perpendicular to the aortic posterior wall. In thirty-one ST-elevation myocardial infarction patients, fourteen MI patients with enlarged LA(≥34mm),(group A), seventeen MI patients with normal-size LA(<34mm),(group B).30 healthy subjects were enrolled as a control group (group C), average age 50.6+12 years,. Those individuals who showed atrial fibrillation, hypertension, diabetes, congenital heart disease, valvular heart disease and old myocardial infarction were excluded, STEMI patients with no known previous history of coronary artery disease were included. All patients were accepted the examination of regular two dimensional and four dimensional echocardiography, including mitral flow velocities, tissue Doppler mitral annular Spectrum speed, and left atrium (LA) phasic volumes. Left atrial ejection fraction (LAEF) was calculated using the formula:0.5×ρ×MAA×A2,where 0.5 is a coefficient, ρ is the blood density 1.06 g/cm3,MAA is the mitral annulus area and A is the peak A wave velocity. The level of B-type natriuretic peptide (BNP) in STEMI group was collected. Correlations between LAEF with BNP, SRs, A-wave velocity, and E/Ea ratio, E/A ratio, LVEDV and LVEF were studied using "Pearson and Spearman’s rhotest. In addition to conventional echocardiographic parameters, the mean systolic peak strain rate(SRs), mean early diastolic peak strain rate(SRe) and mean late diastolic peak strain rate (SRa) of left atrium anterior, lateral, posterior, inferior and septum sites were measured with real-time tri-plane strain rate imaging and calculate the average. Using SPSS 17.0 statistical software to compare the peak strain rate of the left atrium wall.Results:1. Compared with group C, CAD patients in group A had larger left ventricular end diastolic volume (EDV) and left ventricular end systolic volume (ESV), lower left ventricular ejection fraction (LVEF). The difference has statistical significance (P < 0.05); CAD patients in group B did not show significant differences in LV volumes and LV ejection fraction.2. Compared with group C, the peak velocity of mitral A-waves,Ea of group A and B were decreased significantly, E/Ea increased, group A have significantly change. The difference is statistically significant (P< 0.05). The peak velocity of mitral E-waves and E/A ratio in group B have no significant difference with group C (P> 0.05).3. BNP in patients with myocardial infarction were higher than the reference value range; The left atrial maximal volume(LAV max), left atrial minimal volume(LAV min), left atrial pre-systolic volume(LAV pre) and left atrial ejection fraction (LAEF) in group A were significantly higher than groups B and C, the difference was statistically significant (P<0.05), but there was no significant difference between groups B and C.4. Compared with the total strain rate, SRs and SRe of group A and B were significantly lower than those in group C, the difference was statistically significant (P<0.05). SRa of patients in group A was significantly reduced, there was no significant difference in between the group B and C. As to the parameters of all the left atrial walls strain rate, SRs and SRe in group A and B decreased significantly compared with group C (P<0.05), especially Group A, and those differences were statistically significant (P< 0.05). The SRa of all the left atrial walls in group A were significantly decreased compared with group C (P<0.05), SRa of septum site and the anterior, inferior and posterior wall of the left atrium were significantly decreased in group B, while the SRa in the lateral of left atrium was not significantly decreased.5. In our study, Left atrial ejection fraction (LAEF)was strongly correlated to BNP(r=0.715,P=0.001),SRs(r=0.725,P=0.001), A-wave velocity (r=0.787,P=0.001),LAEF was also negatively correlated to E/A ratio(r=-0.668, P=0.001),LVEDV (r=-0.414,P=0.001) and LVEF(r=-0.409,P=0.003)Conclusion:(1) Patients with CAD have significantly reduced LA reservoir function (SRs) and LA passive conduit function (SRe), even they have normal-size left atrium.CAD patients with enlarged LA have significantly reduced LA reservoir function (SRs),passive conduit function (SRe) and booster pump function(SRa).(2) The study shows that in the setting of STEMI treated with primary PCI, as a response to acutely increased filling pressures, LAEF was increased in conjunction with LA volumes. LAEF possibly has also diagnostic importance in the assessment of diastolic dysfunction, but this hypothesis should be confirmed with further studies including more patients.(3) Real-time tri-plane strain rate imaging has the feasibility for assessment of left atrium volume and function in patients with ST-elevation myocardial infarction... |
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