Study Of Correlation Between Abnormal Electrical Activity And Mechanics In Ischemic Cardiomyopathy

Objective: To explore the relationship between electrical activity abnormalities on electrocardiography(ECG) and systolic deformation abnormalities in ischemic cardiomyopathy(ICM), namely each segmental strain, rotating angle and twisting angle of left ventricular wall, recorded by using two-dimensional speckle tracking imaging(2D-STI).Methods: A total of ninety patients with ICM were selected as ischemic cardiomyopathy(ICM) group between September 2014 and November 2015. Meanwhile, another thirty-eight healthy volunteers were enrolled as control group(Con). All subjects of the study in the resting state were conducted 12-lead electrocardiography(ECG), conventional two-dimensional echocardiography and 2D-STI. Patients with ICM were divided into two groups according to QRS duration(QRSd) and heart-rate-corrected QT(QTc) interval respectively. A prolonged QRS duration was defined as greater than or equal to 120 ms. A prolonged QTc interval defined as at least 450 ms for men and 460 ms for women. The routine echocardiographic parameters included left ventricular end-systolic diameters(LVEDs),left ventricular end-diastolic diameters(LVEDd), left ventricular end-diastolic volume(LVEDV), left ventricular end-systolic volume(LVESV),mitral valve early diastolic peak velocity(E) and late diastolic peak velocity(A). Then left ventricular ejection fraction(LVEF) and E/A were calculated.The standard echocardiograophic images were obtained from left ventricular short-axis view at the level of apex, papillary muscle and mitral annulus, and apical view of two, three and four chamber. Strain parameters including circumferential strain(CS), radial strain(RS), longitudinal strain(LS) of each myocardial segment, and rotating angle of apex(Rot-A) and basal(Rot-B) segment were measured automanually.Then the average value of CS and RS at the apical, middle and basal level of left ventricular short-axis view, the average value of LS at the apical, middle and basal segment of left ventricular long-axis view, global circumferential strain(GCS), radial strain(GRS), longitudinal strain(GLS) and the overall peak twisting(Twist) were calculated. Finally, the correlation between QRS duration or QTc interval,of anterior,inferior,anteroseptal,lateral wall as well as the overall heart,and other echocardiographic parameters were analyzed respectively.Results:1.By contrast with Con group, in ICM group, the LVEDs and LVEDd increased, LVEF, E/A, strain-related parameters, Rot-A, Rot-B and Twist lowered, differences were statistically significant(P<0.05).2.Comparion in QRS duration:(1)Compared with QRSd-all(-) group, in QRSd-all(+) group, LVEDd increased, LVEF, GCS, CS-A,CS-M, CS-B, GRS,RS-A,RS-M,RS-B lowered, differences were statistically significant(P<0.05). While, there is no statistical differences in LVEDs,E/A,GLS,LS-A,LS-M,LS-B,Rot-A,Rot-B as well as Twist(P>0.05).(2)Compared with QRSd-ant(-) group, in QRSd-ant(+) group, CS-B and RS-A lowered, differences were statistically significant(P<0.05). While, there is no statistical differences in CS-A,CS-M,RS-M,RS-B,LS-A,LS-M,LS-B(P>0.05).(3)Compared with QRSd-inf(-) group, in QRSd-inf(+) group, RS-B lowered, differences were statistically significant(P<0.05). While, there is no statistical differences in CS-A, CS-M, CS-B, RS-A, RS-M, LS-A, LS-M,LS-B(P>0.05).(4) Compared with QRSd-sep(-) group, in QRSd-sep(+) group, CS-B,RS-A and RS-B lowered, differences were statistically significant(P<0.05). While, there is no statistical differences in CS-A,CS-M,RS-M,LS-A,LS-M,LS-B(P>0.05).(5)Compared with QRSd-lat(-) group, in QRSd-lat(+) group, there is no statistical differences in CS-A, CS-M, CS-B, RS-A, RS-M, RS-B, LS-A,LS-M,LS-B(P>0.05).3. Comparion in QTc interval:(1)Compared with QTc-all(-) group, in QTc-all(+) group, LVEDd increased, LVEF,GCS,CS-M,CS-B,GRS,RS-M,RS-B lowered, differences were statistically significant(P<0.05).While, there is no statistical differences(P>0.05) in LVEDs, E/A, CS-A,RS-A,GLS,LS-A,LS-M,LS-B, Rot-A, Rot-B as well as Twist.(2)Compared with QTc-ant(-) group, in QTc-ant(+) group, RS-B lowered, differences were statistically significant(P<0.05). While, there is no statistical differences in CS-A,CS-M,CS-B,RS-A,RS-M, LS-A,LS-M, LS-B(P>0.05).(3)Compared with QTc-inf(-) group, in QTc-inf(+) group, RS-B lowered, differences were statistically significant(P<0.05). While, there is no statistical differences in CS-A,CS-M,CS-B,RS-A,RS-M, LS-A,LS-M, LS-B(P>0.05).(4)Compared with QTc-sep(-) group, in QTc-sep(+) group, CS-B and RS-B lowered, differences were statistically significant(P<0.05). While, there is no statistical differences in CS-A,CS-M, RS-A,RS-M, LS-A,LS-M, LS-B(P>0.05).(5)Compared with QTc-lat(-) group, in QTc-lat(+) group, CS-M and RS-B lowered, differences were statistically significant(P<0.05). While, there is no statistical differences in CS-A,CS-B,RS-A,RS-M, LS-A,LS-M, LS-B(P>0.05).4.Correlation analysis:(1) Both QRSd-all and QTc-all positively correlated with LVEDd(r=0.441,0.309,P<0.05), and negatively correlated with LVEF, CS-B(r=-0.318,-0.307,P<0.05). QTc-all was also negatively correlated to GRS(r=-0.470,P<0.05).(2) In anterior leads, QRSd-ant negatively correlated with RS-A(r=-0.361,P<0.05). QTc-ant negatively correlated with RS-B(r=-0.351, P<0.05).(3) In inferior leads, QRSd-inf negatively correlated with RS-M(r=-0.350,P<0.05). QTc-inf negatively correlated with RS-B(r=-0.405, P<0.05).(4) In anteroseptal leads, QRSd-sep negatively correlated with CS-B,RS-A and RS-B(r=-0.390,-0.326,-0.342,P<0.05). QTc-sep negatively correlated with CS-B and RS-B(r=-0.322,-0.345,P<0.05).(5)In lateral leads, QTc-lat negatively correlated with CS-M and RS-B(r=-0.399,-0.408,P<0.05).Conclusion: 1.Compared with healthy people, left ventricular enlargement and functional change to different extent as well as regional wall motin can be found in ischemic cardiomyopathy.2.QRS duration or QTc interval prolonging in patients with ischemic cardiomyopathy are accompanied by the further weakening of myocardial deformation ability,especially in CS and RS, and are not related to rotational and twisting motion of heart.3.There is good relation between QRS duration or QTc interval and CS or RS.