Evaluation Of The Effect Of Circumferential Pulmonary Vein Ablation On Left Atrial Function In Patients With Paroxysmal Atrial Fibrillation

Objective:To assess the structural and functional atrial remodeling during long-term follow-up after circumferential pulmonary vein ablation by traditional ultrasound parameter,Tissue Velocity Imaging and Strain Rate Imaging. Analysis the clinical value of the ablation of paroxysmal atrial fibrillation.Methods:Enrolled50consecutive patients with paroxysmal AF that underwent circumferential pulmonary vein ablation. The patients were divided into successful group(n=34) and recurring group(n=16) according the ablation result. All the patients had echocardiography48hours before and6,12weeks after ablation,(1) At four-chamber view, left atrial maximum volume (LAVmax) at end-systole, just before mitral valve opening. Left atrial minimum volume (LAVmin) at end-diastole, just before mitral valve closure, and left atrial preliminary systole volume (LAVIpre) at time of the P wave on the surface electrocardiogram were measured.(2) Calculated total atrial emptying fraction (LAEF), active atrial emptying fraction(LAAEF), passive atrial emptying fraction(LAPEF), atrial expansion index(LAREF)according the formula.(3) At two-chamber, three-chamber and four-chamber view, the velocity, the strain and the strain rate curves was gained in the middle segments of each left atrial wall(left atrial anterior wall,inferior wall, posterior wall, lateral wall and atrial septum)by TVI and SRI. Peak velocity of systole, peak velocity of early diastole, peak velocity of late diastole, the time difference of all left atrial wall which from P wave to the time peak velocity of late diastole (△T), peak strain rate of systole, peak strain rate of early diastole, peak strain rate of late diastole and maximum strain were measured. Calculated average of the peak velocity, peak strain rate and the standard deviation of△T each wall.Results:(1) Compared with6weeks after ablation, LAVImax, LAVImin, LAVIpre of total study population12weeks after ablation were reduced significantly (p＜0.05), the result of the successful group was similar. Compared with6weeks after ablation, LAVImin, LAVIpre of recurring group12weeks after ablation were reduced significantly (p＜0.05). There was no significant difference of the left atrial volume was found between the two groups before the ablation. But the significant difference of the LAVImax was found between the two groups12weeks after ablation.(2) Compared with before ablation, LAEF, LAAEF, LAREF of total study population12weeks after ablation were increased significantly (p＜0.05), the result of the successful group was similar, There was no significant difference of left atrial ejection fraction was found in recurring group between before and12weeks after ablation (p＞0.05) There was no significant difference of the left atrial ejection fraction was found between the two groups before the ablation. But the significant difference of the LAEF, LAREF, LAPEF was found between the two groups12weeks after ablation (p＜0.05).(3) Compared with before the ablation, the average of Vs, Ve, Va of total study population12weeks after ablation was increased, but had no significant (p＞0.05). Compared with before the ablation, Va of successful group and Vs of recurring group12weeks after ablation were increased significantly (p＜0.05). There was no significant difference of the velocity was found between the two groups (p＞0.05). There was no significant difference of the△Ts was found in all groups between before and12weeks after ablation (p＞0.05).(4) Compared with before the ablation,the average of SRs, SRe, SRa and S of total study population12weeks after ablation was increased significantly (p＜0.01). the result of the successful and recurring group was similar. There was no significant difference of the strain was found between the two groups before the ablation, but compared with the successful group SRe, SRa and S were reduced significantly12weeks after ablation (p＜0.05)Conclusions:(1) Circumferential pulmonary vein ablation can affect the structural atrial remodeling, reduce the atrial volume, the ablation lesions can not affect the atrial volume significantly.(2) The functional atrial remodeling was observed at the same time.(3) The atrial peak velocity had a trend to increase after the ablation, the lesions made by isolation of PVs can not affect the atrial peak velocity and synchronism of the left atrial significantly.(4) Peak strain rate increased significantly after the ablation, the atrial deformation capability was significantly increased after the ablation.(5) The structural and functional atrial remodeling can still be observed in recurring patients because the reduction of AF burden after the ablation.