Evaluation Of Left Ventricular Diastolic Function And Influencing Factors In Patients With Complete Left Bundle Branch Block With Normal Left Ventricular Ejection Fraction By Echocardiography

Objective: Studies have shown that left ventricular systolic function and synchrony have been reduced in complete left bundle branch block(CLBBB)with normal left ventricular ejection fraction(LVEF)and the reduction is more significantly in patients with QRS duration widening and ventricular septal flash(SF).However,the influencing factors of left ventricular diastolic function changes remain unclear.Most cardiovascular diseases have a certain effect on left ventricular diastolic function since the onset of diseases,which may occur before LVEF reduction.This study aims to evaluate left ventricular diastolic function and synchrony and influencing factors in isolated CLBBB patients with normal LVEF by echocardiography,to provide important information for clinical judgment of the condition.Methods: Patient selection: A total of 62 isolated CLBBB patients with normal LVEF were included in this study as case group(CLBBB group).And 50 healthy people with matching age and sex were included as control group(Con group).Echocardiographic procedure:Left ventricular diastolic function: Conventional echocardiography and 2D-speckle tracking echocardiography(2D-STE)were performed to detect left atrium volume index(LAVI),mitral flow early and later diastolic velocity(E and A),septal mitral annulus early diastolic velocity(e?).Calculated E/A and E/e?;peak tricuspid regurgitation velocity(TR);left ventricular global peak early diastolic longitudinal strain rate(SRe),calculated E/SRe.Left ventricular diastolic synchrony: 2D-STE was performed to detect standard deviation of left ventricular 18 segments peak early diastolic longitudinal strain rate(LSRe-SDt).Left ventricular systolic function and synchrony: 2D-STE was performed to detect left ventricular systolic longitudinal strain(GLS)and standard deviation of left ventricular 18 segments peak systolic longitudinal strain time(LV-SDt).Interventricular synchrony: Doppler imaging was performed to detect the time difference between left ventricular outflow tract pre-ejection period and right ventricular outflow tract pre-ejection period(IVMD).Influencing factors: to explore the effect of electrocardiographic QRS duration,SF,GLS and LV-SDt on left ventricular diastolic function in Group CLBBB.Results:1.Left ventricular diastolic function and synchrony between CLBBB group and Con group Compared with Con group,E,A,E/A,e? and SRe were significantly decreased(P <0.001),while LAVI and E/e? were significantly increased(P < 0.001).In addition,LSRe-SDt was significantly prolonged in CLBBB group,suggesting that both left ventricular diastolic function and left ventricular diastolic synchrony were decreased.2.Subgroup analysis2.1 According to the QRS time limit,CLBBB group were divided into two groups:wide QRS group(QRS > 150ms)and narrow QRS group(QRS between 120 ms and 150ms).Compared with Con group,E,A,E/A and SRe in both wide QRS group and narrow QRS group decreased(P < 0.01),and LSRe-SDt increased.However,e? decreased,E/SRe decreased,LAD increased and LAVI increased were observed only in wide QRS group.Compared with narrow QRS group,e? and SRe decreased,LAD and E/SRe increased in wide QRS group(P < 0.05),and LSRe-SDt showed no significant difference(P > 0.05).The above results suggested that left ventricular diastolic function reduction was more significant in CLBBB patients of wide QRS group,but QRS duration had no significant effect on left ventricular diastolic synchrony.2.2 According to whether SF exists,CLBBB group were divided into two groups:SF group(with SF)and the NSF group(without SF).Compared with Con group,E,A,E/A and SRe in both SF group and NSF group were significantly decreased(P < 0.01),while E/e? and LSRe-SDt were significantly increased(P < 0.01).Compared with NSF group,SRe decreased more significantly in SF group(P<0.01),while LSRe-SDt showed no significant difference(P > 0.05).The above results suggested that left ventricular diastolic function reduction was more significant in CLBBB patients with SF,but SF had no significant effect on leftventricular diastolic synchrony.2.3 According to GLS value,CLBBB group were divided into two groups:decreased GLS group(GLS <-20%)and normal GLS group(GLS ?-20%).Compared with Con group,E,SRe were decreased in both decreased GLS group and normal GLS group(P < 0.01),while A decreased and LAD,LAVI,E/SRe and LSRe-SDt increased were only observed in decreased GLS group.Compared with normal GLS group,e? decreased,SRe decreased,E/e increased and E/SRe increased more significantly in decreased group(P < 0.05),LSRe-SDt showed no significant difference(P > 0.05).The above results suggested that left ventricular diastolic function reduction was more significant in CLBBB patients with decreased GLS,but GLS had no significant effect on left ventricular diastolic synchrony.3.Influencing factors of left ventricular diastolic function3.1 Reduction of e?: Correlation analysis showed that age,systolic blood pressure,diastolic blood pressure,left ventricular end-diastolic diameter,left ventricular end-systolic diameter,heart rate,LS-SDt,SF existing and GLS were linearly correlated with e'(P < 0.05).Multiple linear regression analysis showed that LS-SDt increase(?=-0.440),SF existing(?=0.617)and GLS decrease(?=0.381)were the main influencing factors for e' decrease(R2=0.45,P < 0.001).3.2 Increase of E/e?: Correlation analysis showed that age,systolic blood pressure,GLS,LS-SDt and SF existing were linearly correlated with E/e?(P < 0.05).Multiple linear regression analysis showed that age increase(?= 0.261),GLS decrease(?=-0.542)and SF existing(?=-0.388)were the main influencing factors for increased E/e'(R2=0.35,P< 0.001).3.3 Increase of E/SRe: Correlation analysis showed that QRS duration,IVMD,LVEF and GLS were linearly correlated with E/SRe increase(P < 0.05);While multiple linear regression analysis showed that QRS duration widening was an independent risk factor for E/SRe increase(?=0.509,R2=0.25,P < 0.001).In conclusion,QRS duration widening,SF existing,GLS decrease and LV-SDt increase had significant effects on left ventricular diastolic function reduction in CLBBB group.Conclusion:1.Left ventricular diastolic function and synchrony decrease in CLBBB patients with normal LVEF.2.QRS duration,SF,left ventricular systolic function and systolic dyssynchrony are the main influencing factors for left ventricular diastolic function in CLBBB patients,but the effect on left ventricular synchrony is not significant.3.Clinically,isolated CLBBB patients with wide QRS duration,SF,GLS reduction and left ventricular systolic dyssynchrony should be paid close attention and followed up regularly.