Clinical Research On Evaluating Left Atrial Function And Predicting Left Atrial Appendage Stasis In Patients With Atrial Fibrillation By Strain And Strain Rate Imaging

Objective:To evaluate left atrial?LA?function using strain and strain rate imaging?S/SRI?in patients with paroxysmal atrial fibrillation?PAF?and to investigate the value of LA S/SR in predicting left atrial appendage?LAA?stasis in patients with nonvalvular atrial fibrillation?NVAF?.Methods:Part 1:57 patients with PAF were divided into two groups:PAF1:32 patients with LA volume indexes?LAVI??34 mL/m²and PAF2:25 patients with LAVI>34 mL/m².In addition,29 age-matched normal subjects were enrolled as controls.The LA S/SR of the three groups was analyzed with the reference point at the onset of P-wave.The following indices were measured from the strain-time and SR-time curves in apical4-,2-and 3-chamber views:1.The mean peak atrial longitudinal S/SR during atrial booster pump(S_pump,SR_pump),reservoir(S_res,SR_res),and conduit(S_cond,SR_cond)phase.All Biplane-S/SR indices were calculated by averaging the values obtained in the apical 4-chamber and 2-chamber views,to represent LA global function.2.The time to peak atrial longitudinal strain?TpS?and the time to peak atrial longitudinal SR?TpS?with reference to the onset of P-wave of 15 segments of LA wall in each phase.The LA dyssynchrony in each phase was defined as the standard deviation of 15 TpS or TpSR parameters in this phase.The LA S/SR and synchrony indices among the three groups were compared.Part 2:With the reference point at the onset of QRS-wave,the LA S/SR was analyzed in 130 NVAF patients.S_res,SR_reses and SR_condond were acquired in apical 4-and 2-chamber views,respectively,to calculate Biplane-LAS/SR.Measurements of LAA functional parameters,analysis of LA or LAA spontaneous echo contrast?SEC?grade and confirmation of thrombus were performed on TEE.LAA stasis was defined when dense SEC?grade 3+or 4+?or thrombus was present in LA or LAA.Based on the presence of LAA stasis,130 NVAF patients were divided two groups to compare LA S/SR.The correlations were analyzed between LA S/SR with LAA functional parameters and LAA SEC grade.The receiver operating characteristic?ROC?curves were constructed to determine the optimal cut-off values of LA S/SR to predict LAA stasis.A logistic regression analysis was performed to determine the independent predictors of LAA stasis.Results:Part 1:Biplane-LAS_pump,Biplane-LASR_pump,Biplane-LAS_reses and Biplane-LASR_reses were lower in PAF1 than in controls and were further reduced in PAF2?P<0.05?.Compared with the control group,Biplane-LAS_condond and Biplane-LASR_condond were decreased in PAF1and PAF2?P<0.05?.No significant differences were observed between the PAF1 and PAF2 groups.Compared with the control group,the asynchronization parameters of TpS_pump-SD were significantly higher in PAF1 and PAF2?P<0.05?.TpS_res-SD was significantly higher in PAF2than in control group?P<0.05?,but no significant differences were found between PAF1 and control or PAF1 and PAF2.No significant differences in TpSR-SD were observed in each phase among the three groups.Part 2:On TEE,21 patients?16%?showed LAA stasis.Such patients manifested significantly lower LA S/SR than those without such changes?P<0.05?.4C-,2C-,and Biplane-LA reservoir S/SR not only showed a moderate correlation with LAA functional parameters,including LAA emptying fraction and LAA peak emptying flow velocity,but also a significant rank correlation with LAA SEC grade.Significant differences were seen in LA reservoir S/SR between each grade of LA SEC?P<0.05?.No significant differences existed in correlation coefficients with LAA functional parameters and the areas under the ROC curve?AUC values?of4C-,2C-,and Biplane-LA reservoir S/SR?P>0.05?.In multivariate logistic regression analysis,4C-LAS_reses was an independent predictor of LAA stasis.4C-LAS_res<13%was recommended to predict LAA stasis with 90%sensitivity and 74%specificity.Conclusions:?1?LA function was already impaired in patients with PAF with normal LA size,which was manifested as lower LA myocardial deformation and higher LA dyssynchrony,and was further deteriorated when LA was enlarged.S/SRI may be considered a promising tool for the early detection of abnormal LA mechanical function.?2?LA S/SR by TTE is predictive of LAA stasis in patients with NVAF.4C-LAS_reses is an independent predictor of LAA stasis.4C-LAS_res<13%is recommended for screening LAA stasis in NVAF patients.