Impacts Of Preoperative Left Atrium Function And Atrial Endocardial Expression Of VWF And TM On The Recurrence After Minimally Invasive Surgical Atrial Fibrillation Ablation

Part Ⅰ.The impact of preoperative left atrium function on the recurrence after minimally invasive surgical atrial fibrillation ablation Objective: Accurate evaluation of left atrium size and function is getting more attraction because of their role in diagnosis,treatment,and prognosis of atrial fibrillation(AF).However,there have been limited reports about the impact of left atrium(LA)function on the recurrence after minimally invasive surgical AF ablation.This study retrospectively analyzed the data from non-valvular AF patients who underwent procedure at our center.We focused on the role of preoperative LA function in predicting postoperative AF recurrence.Methods: From October 2010 to May 2014,a total of 114 patients underwent minimally invasive surgical AF ablation at Shanghai Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine.All these patients underwent preoperative echocardiography to evaluate cardiac function(including LA function).All patients completed at least 2-year follow-up.Follow-up protocol included physical examination,12-lead electrocardiography(ECG),and 24-hour Holter monitoring at 3,6,12,and 24 months.AF episodes within the first 3 months after the procedure was not considered recurrence since the first 3 months was blanking period.After blanking period,any atrial tachyarrhythmia(ATA)(including AF,atrial tachycardia,or atrial flutter)lasting ≥ 30 seconds,regardless of clinical symptoms,is considered recurrence.Results: All patients underwent successful procedure.No patient died in the perioperative period and there was no conversion to sternotomy.At discharge,105 patients(92.1%)were in sinus rhythm.At the 2-year interval,99 patients(86.8%)maintained sinus rhythm and all were off antiarrhythmic drugs.The sinus rhythm rate for paroxysmal AF(PAF)patients was 90.2%(55/61),while for non-paroxysmal AF(Non-PAF)patients it was 83.0%(44/53).When analyzing risk factors for AF recurrence,univariable analyses showed that AF duration,left atrial diameter(LAD),left atrial emptying fraction(LAEF),and left atrial active emptying fraction(LAAEF)were risk factors for AF recurrence(P<0.05),while Non-PAF was not(P=0.257).In multivariable analyses,LAD,AF duration,LAEF and LAAEF separately remained risk factors for AF recurrence(P<0.05).However,LAPEF was not shown to be risk factor(P=0.067).Receiver operating characteristic(ROC)curves showed that cut-off values were: LAD 43.5mm,LAEF 21.6%,and LAAEF 12.1%.Kaplan-Meier analyses suggested that the sinus rhythm rate for patients with LAD ≥ 43.5mm was lower than those with LAD < 43.5mm(P<0.001),while patients with LAEF ≥ 21.6% and LAAEF ≥ 12.1% had higher sinus rhythm rate compared with those with LAEF < 21.6% and LAAEF < 12.1%,respectively(P<0.001 for both).There was no difference in sinus rhythm rate between PAF and non-PAF patients(P=0.250)Conclusion: LA function is closely associated with the recurrence after minimally invasive surgical AF ablation.LAEF,LAAEF,LAD,and AF duration were risk factors.Patients with PAF and non-PAF had similar sinus rhythm rate after the procedure.Part Ⅱ.The impact of preoperative atrial endocardial expression of v WF and TM on the recurrence after minimally invasive surgical atrial fibrillation ablation Objective: Very few studies have focused on endocardial changes during atrial fibrillation(AF).Even though there were limited reports about endocardial changes during AF,most of them were about thrombus formation.However,there is evidence that not only that endocardial expression of certain factors are associated with thrombus formation(e.g.von Willebrand Factor(v WF)and thrombomodulin(TM)),but also that they are associated with atrial distension,remodeling,and fibrosis,which are important risk factors for postoperative AF recurrence.This study retrospectively analyzed the data from non-valvular AF patients who underwent minimally invasive surgical AF ablation at our center.Our purpose is to explore the atrial endocardial expression of v WF and TM and their association with rhythm results after minimally invasive surgical AF ablation.Methods: From January 2013 to October 2014,52 patients with non-valvular AF underwent minimally invasive surgical AF ablation at Shanghai Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine.All these patients were divided into two groups: paroxysmal AF(PAF)and non-paroxysmal AF(non-PAF).Non-PAF included persistent AF and long-standing persistent AF.Left atrial appendage(LAA)samples were obtained during the procedure and immunohistochemistry for endocardial markers including v WF and TM was performed and semiquantitatively graded.Western blot analysis was also performed.In immunohistochemistry,each slide was scored as having no staining,weak focal staining,multifocal moderate staining,or diffuse strong staining,giving a score of 0,1,2,or 3,respectively.All patients underwent rhythm documentation at 3,6,12,and 24 months with electrocardiography(ECG)and Holter monitoring.AF episodes within the first 3 months after the procedure was not considered recurrence since the first 3 months was blanking period.After blanking period,any atrial tachyarrhythmia(ATA)(including AF,atrial tachycardia,or atrial flutter)lasting ≥ 30 seconds,regardless of clinical symptoms,is considered recurrence.Results: All patients underwent successful procedure.No patient died in the perioperative period and there was no conversion to sternotomy.All patients finished complete rhythm documentation at 3,6,12,and 24 months with ECG and Holter monitoring.At discharge,43 patients(82.7%)were in sinus rhythm.At the 2-year interval,43(82.7%)patients maintained sinus rhythm and all were asymptomatic.Nine(17.3%)patients(3 with PAF and 6 with non-PAF)had AF recurrence.No patients experienced postoperative stroke.The left atrial diameter(LAD)was larger in patients with AF recurrence compared with those with sinus rhythm(47.1 ± 4.1 vs 42.4 ± 7.6,P=0.033).The expression of v WF in the LAA was more intense in patients with AF recurrence compared with those with sinus rhythm(P=0.027).The expression of TM in the LAA,on the other hand,was less intense in patients with AF recurrence compared with those with sinus rhythm(P=0.043).Western blot analysis also confirmed the results of immunohistochemistry.A higher staining intensity(score 2/3)of v WF was associated with a larger LAD(45.2 ± 5.7mm vs.41.8 ± 8.1mm,P=0.044),while a higher staining intensity(score 0/1)of TM was associated with a smaller LAD(45.4 ± 6.1mm vs.38.3 ± 7.8mm,P=0.046).Kaplan-Meier analysis showed that a higher staining intensity of v WF(score 2 or 3)and a lower intensity of TM(score 0 or 1)were associated with postoperative AF recurrence(v WF: P=0.016;TM: P=0.033).Conclusion: Atrial endocardial expression of v WF and TM are closely associated with the recurrence after minimally invasive surgical AF ablation.Increased expression of v WF and decreased expression of TM in the atrial endocardium are risk factors for AF recurrence in patients with non-valvular AF.