Magnetic Resonance For Quantitative Evaluation On Left Ventricular Myocardial Strain In Ventricular Arrhythmia

Objective: To investigate left ventricular myocardial strain and function in ventricular arrhythmias(VA)with structurally normal hearts using the short-3D and feature-tracking post-processing technique of cardiac magnetic resonance(CMR).Materials and methods: We included 39 patients with VA(VA group),which contained 24 frequent premature ventricular complexes(frequent PVCs)and 15non-sustained ventricular tachycardia(non-sustained VT),and 20 normal volunteers(control group)from the second affiliated hospital of Nanchang University.The cohort underwent CMR at rest,including left ventricular short axial and long axis(vertical and horizontal planes)cine images.Left ventricular end-diastolic volume(EDV),end-systolic volume(ESV),left ventricular ejection fraction(LVEF),global radial strain(Err),global circumferential strain(Ecc),global longitudinal strain(Ell),global radial/circumferential/longitudinal time to peak strain(TTPrr/TTPcc/TTPll),global peak radial/circumferential/longitudinal systolic and diastolic strain rate(SRrr,SRcc,SRll/DSRrr,DSRcc,DSRll)and segmental peak strain were assessed.VA group were divided into frequent PVC and non-sustained VT group.The EDV,ESV,LVEF,Err,Ecc,Ell,TTPrr,TTPcc,TTPll,SRrr,SRcc,SRll,DSRrr,DSRcc,DSRll and segmental peak strain in multiple groups were compared by One-Way ANOVA or Kruskal-Wallis test.A Spearman correlation test was used to determine the relationships between LVEF and Err,Ecc,Ell,DSRrr,DSRcc,DSRll.Bland-Altman analysis was performed for the assessment of intra-and inter-observer reproducibility.Results: Compared to control group and non-sustained VT group,Err,Ecc and Ell decreased in frequent PVC group(p<0.01),while the corresponding time-to-peak reached later(p<0.05).The SRrr,SRcc,DSRcc and DSRll in frequent PVC group were lower than controls(p<0.05),while the values of SR and DSR in three directions decreased compared to non-sustained VT group(p<0.05).And the LVEF in patients with frequent PVC was lower than controls(p<0.01),EDV and ESV weresimilar to controls and non-sustained VT group(p>0.05).The above parameters had no significantly difference between non-sustained VT and control group(p>0.05).Compared to the other two groups,the peak radial,circumferential and longitudinal strain in the basal and middle parts of LV were lower in frequent PVC group(p<0.05),while the corresponding time-to-peak reached delay(p<0.05).But the values of peak strain and time-to-peak in non-sustained VT were no statistically significant different compared to control group(p>0.05).Compared to controls,the distribution trend of the peak strain in the radial,circumferential and longitudinal directions of VA patients from basal to apex were consistent basically.In frequent PVC group,the peak segmental radial,circumferential and longitudinal strain were reduced significantly in the anterior,septal and lateral segments compared with the same segments in control and non-sustained VT(p<0.05).While compared to control subjects,the peak segmental strain had no statistical decreased in non-sustained VT group(p>0.05).LVEF was positively correlated with Err,DSRcc and DSRll(r=0.559,p=0.000;r=0.447,p=0.000;r=0.377,p=0.000;respectively).Ecc,Ell and DSRrr were nominal negatively correlated with LVEF(r=-0.59,p=0.000;r=-0.464,p=0.000;r=-0.479,p=0.000;respectively).On Bland-Altman analysis,global circumferential strain had the best intra-and inter-observer agreement(bias-1.52±2.12% and2.15±1.25%).Conclusion: Cardiac magnetic resonance can quantitative evaluate the left ventricular dysfunction in ventricular arrhythmia patients without overt cardiovascular disease.And CMR tissue tracking technology can identify the regional myocardial dysfunction by segmental strain,which is better than LVEF.In clinical work,CMR tissue tracking has the potential to detect subtle LV dysfunction,which provide basis for therapy planning and treatment of VA patients.