The Relationships Between Peri-Operation Anticoagulation Therapy And Thromboembolic Events In Patients With Atrial Fibrillation Who Underwent Radiofrequency Catheter Ablation

Background and Objective:Atrial fibrillation(AF),one of the most common persistent arrhythmia in clinical practice,is associated with many kinds of symptoms and may increase the risk of stroke.Recently,radiofrequency ablation has become an available therapy for patients with symptomatic AF who are resistant to medical treatment.Thromboembolism is a severe complication associated with AF as well as with ablation of AF.The relationships between different anticoagulation methods and thromboembolic events during or after radiofrequency ablation of AF in our center were evaluated.Methods:From July 2004 to October 2007,ablation of AF was consecutively performed in 393 patients who had accepted anticoagulation with warfarin before the procedure, which including 145 persistent/permanent AF and 248 paroxysmal AF.Spiral pulmonary vein CT angiography(CTA) and transesophageal echocardiography(TEE) were performed prior operation to exclude thrombus in atrium,especially in left atrial appendage.Anticoagulation with warfarin was administrated in all patients before operation for at least 1 month,with the international normalized ratio(INR) maintained between 2.0 and 3.0.Low molecular weigh heparin(LMWH) was used to replace warfarin 3 days before operation.All patients were divided into two groups:groupⅠconsisted of patients who underwent ablation of AF from July 2004 to January 2006,4000～5000U intravenous heparin were given after atrial septum puncture;groupⅡconsisted of patients who underwent ablation of AF from February 2006 to October 2007,who were heparinized(100U/Kg) after atrial septum puncture.During the operation,1000U heparin(including the dose of heparin perfusing with saline through irrigated ablation catheter) were appended per hour.LMWH was initiated after operation together with warfarin for 3 days.After the procedure,warfarin was used for at least 3 months in all patients. Peri-operation thromboembolic events were identified by in-hospital observation, outpatient clinic visit and telephone interview follow-up.The potential risk factors associated with the thromboembolic events were analysed.Results:Thromboembolic events(thrombosis and embolism) were identified in four persistent/permanent AF patients in groupⅠ(6.25%,4/64).One thrombus(thrombosis) on the tip of ablation catheter was found by intracardiac echocardiography(ICE) during current delivery,but no embolism complication was observed. Thromboembolic events occurred in 3 patients after operation(4.69%,3/64).In contrast,no thromboembolic event was observed in patients with paroxysmal AF.The incidence of thromboembolic event in patients with persistent/permanent AF was higher than that in patients with paroxysmal AF(4/64 vs.0/84,P=0.033).Transient ischemic attack(TIA) was identified in one persistent AF patient (female,81 years old) of groupⅡand this patient didn't fulfill the anticoagulation therapy after ablation.No other thromboembolic event was identified in groupⅡpatients.Excluding the patient with TIA,the incidence of thromboembolic event in groupⅡwas 0%.The incidence of thromboembolic event of persistent/permanent AF in groupⅡis lower than that of groupⅠ(4/64 vs.0/80,P=0.037).The incidence of thromboembolic event was 1.27%(5/393) in this series patients.Significant difference in the incidence of thromboembolism between patients with paroxysmal AF(0%) and those with persistent/permanent AF(3.45%,5/145, P=0.007) was found.Compared with persistent/permanent AF patients without thromboembolic events,patients with thromboembolic events were characterized with higher weight(76.7±9.6 Kg vs.69.4±7.4 Kg,P=0.032),older age(65.8±10.0 years vs.55.8±10.5 years,P=0.039),more augmented left atrium(48.4±2.6 mm vs.43.4±5.2 mm,P=0.037) and lower left ventricular ejection fraction(LVEF)(0.60±0.05 vs.0.66±0.06,P=0.030).Multivariate logistic analysis showed that higher weight (OR=1.314,95%CI 1.047～1.647,P=0.018) and older age(OR=1.308,95%CI 1.053～1.624,P=0.015) were independent risk factors of thromboembolic events in patients with persistent/permanent AF who underwent radiofrequency catheter ablation.No significant difference in gender,course of disease,persistent time of AF and left ventricular end diastolic/systolic diameter was observed between persistent/permanent patients with and without thromboembolic events. Conclusions:With the improvement of anticoagulation therapy during ablation,the incidence of thromboembolic event in patients with persistent/permanent AF become lower and lower,which is similar to those in patients with paroxysmal AF.During or after ablation,persistent/permanent AF patients with higher weight,older age,more augmented left atrium and lower EF have a higher risk of thromboembolism.Higher weight and older age were the two independent risk factors of thromboembolic events in patients with persistent/permanent AF who underwent radiofrequency catheter ablation.