Effect Of Atorvastatin On Left Ventricular Systolic Function In Rats Models With Myocardial Infarction

Objective: The incidence of myocardial infarction(MI)is increasing year by year accompanied by a younger trend.In 2016,statistics of WHO showed that acute myocardial infarction(AMI)has become the leading cause of human death.One of the most important mechanisms of human death caused by MI is the reduction of cardiac contractility.Atorvastatin who has pleiotropic characteristics maybe improve the cardiac contractile function on the basis of lipid-regulating,and reduce the incidence and mortality of MI.This report aims to evaluate the effect of atorvastatin(Ator)on left ventricular(LV)systolic function in MI rats using two-dimensional speckle tracking technique(2D-STI).Methods: 60 adult Sprague-Dawley(SD)rats were randomly divided into Ator group,MI group,sham-operation group and normal group,the Ator group was divided into A,B,C 3 subgroups.So there were 6 groups(n=10 in each group).The left anterior descending coronary arteries(LAD)were ligated to establish MI model in Ator groups and MI group.Given treatment of Ator to Ator A group,Ator B group,Ator C group for 4 weeks with the dose of 10 mg/kg/d,20mg/kg/d or 40 mg/kg/d respectively.Echocardiographic detection was performed once a week before and after MI for each animal.Measured and analyzed the changes of velocity,strain,strain rate of LV regional myocardium by 2D-STI.After 4 weeks of treatment with Ator,all rats were received myocardial Hematoxylin—eosin staining.Results:(1)Compared with those before operation and compared with those in normal group and sham-operation group after operation at the same time,left ventricular end-diastolic diameter(LVEDD)and left ventricular end-systolic diameter(LVESD)in Ator groups and MI group were increased after operation,but left ventricular ejection fraction(LVEF)and left ventricular fractional shortening(LVFS)were decreased;the radial,circumferential and longitudinal myocardial systolic peak velocities,strain and strain rates of anteroseptal,posteroseptal,left ventricular anterior walls and apex were decreased significantly,and the differences were statistically significant(p<0.05).(2)Compared with those at the 1st and 2nd weeks after operation,LVEDD and LVESD increased while LVEF and LVFS decreased in MI group at the 4th weeks after operation,the radial,circumferential and longitudinal myocardial systolic peak velocities,strain and strain rates of anteroseptal,posteroseptal,left ventricular anterior walls and apex still decreased in MI group;the radial,circumferential and longitudinal myocardial systolic peak velocities,strain and strain rates of anteroseptal,posteroseptal,left ventricular anterior walls and apex in Ator groups at the 3rd and 4th weeks after operation were increased.The differences were statistically significant(p<0.05).(3)Compared with the MI group,at the 1st week after operation,LVEDD,LVESD,LVEF and LVFS in Ator groups,as well as the radial,circumferential and longitudinal myocardial systolic peak velocities,strain and strain rates of anteroseptal,posteroseptal,left ventricular anterior walls and apex in Ator A group and Ator B group had no statistically significant differences(P>0.05);but the radial,circumferential and longitudinal myocardial systolic peak velocities,strain and strain rates of anteroseptal,posteroseptal,left ventricular anterior walls and apex in Ator C group increased(P<0.05);at the 2nd week,LVEDD,LVESD,LVEF and LVFS in Ator groups had no statistically significant differences(P>0.05);at the 3rd and 4th weeks,LVEDD and LVESD decreased while LVEF and LVFS increased in Ator groups(P<0.05);at the 2nd,3rd and 4th weeks,the radial,circumferential and longitudinal myocardial systolic peak velocities,strain and strain rates of anteroseptal,posteroseptal,left ventricular anterior walls and apex in Ator groups increased(P<0.05).(4)After operation,LVEDD,LVESD,LVEF and LVFS between Ator A,B,C groups showed no statistically significant differences(P>0.05);the radial,circumferential and longitudinal myocardial systolic peak velocities,strain and strain rates of anteroseptal,posteroseptal,left ventricular anterior walls and apex between Ator groups had no statistically significant differences at the 1st weekafter operation,(P>0.05);but at the 3rd and 4th weeks,the radial,circumferential and longitudinal myocardial systolic peak velocities,strain and strain rates of anteroseptal,posteroseptal,left ventricular anterior walls and apex in Ator B and C groups increased than Ator A group;there were no statistically significant differences between Ator B and C groups(P>0.05).(5)There were no statistically significant differences in the radial,circumferential and longitudinal systolic peak velocities,strain and strain rates of left ventricular lateral,posterior,inferior walls between and within the 4groups(P>0.05).(6)Pathological examination showed that necrosis and fibrosis of myocardial cells and inflammatory reaction were obvious in MI group.The inflammatory reaction of myocardial cells and myocardial fibrosis in Ator A group were lighter than those in MI group,but more serious than those in Ator B and C groups.Conclusion: Ator can effectively improve the left ventricular systolic function in MI rats.20 mg/kg/d may be the optimal dose of Ator to improve the left ventricular systolic function after MI.