Risk of Stroke and Recurrence After AF Ablation in Patients With an Initial Event-Free Period of 12 Months

Simon Kochhäuser, M.D.; Pouria Alipour, B.Sc.; Tanjah Haig-Carter, B.Sc.; Kathleen Trought, B.Sc.; Philip Hache, B.Sc.; Yaariv Khaykin, M.D.; Zaev Wulffhart, M.D.; Alfredo Pantano, M.D.; Bernice Tsang, M.D.; David Birnie, M.D.; Atul Verma, M.D.

Disclosures

J Cardiovasc Electrophysiol. 2017;28(3):273-279. 

In This Article

Materials and Methods

Patient Population and Data Collection

From our ablation database, consecutive patients were identified that underwent AF ablation between 2006 and 2013. The decision to perform AF ablation was based on the recommendations of the Canadian Cardiovascular Society (CCS) and the American Heart Association (AHA) that were valid at the respective time and made in conjunction with the patient. Typically, the decision to ablate was based on significant symptoms affecting quality of life, documented AF, and refractoriness to 1 or more antiarrhythmic drugs (AAD). All patients underwent follow-up (FU) at 3, 6, 9, and 12 months after ablation. FU past the 1st year was performed every 6–12 months. For the purpose of this study there was no direct contacting of patients outside of a clinical setting. At each FU, a minimum of one 12-lead ECG and a 48-hour Holter were performed. If patients reported symptoms suspicious for recurrence, they also underwent additional 2-week external loop recording to confirm recurrences of AF or other atrial tachycardias (AT) like atrial flutter or focal AT. Patients with a repeat ablation would be followed with the same intervals as patients who underwent a first ablation. Recurrence was defined as any documented or patient reported episode of AF/AT lasting more than 30 seconds. Only patients who were free of AF/AT recurrence 12 months after their last AF ablation were included.

Baseline characteristics were collected at the time of each ablation procedure, but for purposes of reporting in this study, they are based on the characteristics at the most recent ablation. All decisions regarding patient care (e.g., discontinuation of OAC or antiarrhythmic drug) were made by the treating physician in conjunction with the patient. In addition to the standard rhythm monitoring described above, each FU appointment also consisted of a review of recent hospitalizations and review of any adverse events including stroke and/or transient ischemic attack (TIA). Whenever possible, documentation of a reported stroke or TIA event or a recurrence of AF/AT was obtained from our hospital or partner hospital records. All data was collected in accordance with our institutional ethics review board guidelines.

Ablation Protocol

Our ablation protocols have been described in detail in a prior publication.[19] In brief, ablation was performed under conscious sedation or general anesthesia. After vascular access through the femoral veins, a 10-polar catheter was placed into the coronary sinus. Left atrial access was obtained through double transseptal puncture. After transseptal access, all patients were anticoagulated with intravenous heparin to maintain an activated clotting time of >300 seconds. A 3-dimensional electroanatomic mapping system was used to help guide ablation. Pulmonary vein isolation was performed in all patients using a standard, wide circumferential antral ablation (at least 2 cm outside of the pulmonary vein ostium) using an open irrigated radiofrequency ablation catheter. A decapolar circular mapping catheter was sequentially placed into each of the pulmonary venous antra during ablation and radiofrequency lesions were applied until all PV potentials within each antrum were abolished. In patients with persistent AF, additional ablation was performed at LA sites exhibiting complex fractionated electrograms until those electrograms were abolished. Additional linear ablation was also performed in some patients who had left AT/flutters, most typically on the roof and less commonly at the mitral isthmus, with the endpoint of block across the lines.

OAC was continued for a minimum of 3 months after the ablation as per guidelines.[1] The decision whether to continue OAC past 3 months was based primarily on the patient's risk of stroke (CHADS2-score), recurrence of AF/AT, and the wishes of the patient. All decisions regarding OAC or antiarrhythmic therapy were made at our clinic or in consultation with the treating physician at our center. The use of acetylsalicylic acid was recommended in the majority of patients in whom OAC was discontinued. No other antiplatelet drug was used.

Statistics

All statistical analysis were performed using SPSS 22.0 (IBM Corporation, Armonk, NY, USA). Continuous parametric variables are expressed means (± standard deviation) or median (1st Quartile, 3rd Quartile) in the case of non-normal distribution. Categorical variables are listed as number (percentage). For comparison of means, Pearson's chi-square or Fishers exact test were used for categorical variables and the Mann–Whitney-U test for continuous variables. Distribution of normality in continuous variables was tested with the Shapiro-Wilks test. Univariable and multivariable binary regression were performed to identify predictors of AF/AT recurrence. Receiver operating characteristics (ROC) curves were analyzed and the area under the ROC curve (AUC) was calculated to analyze the general diagnostic quality of the CHADS2- and CHA2DS2-VASc-score as predictors of AF/AT recurrence. Shown P values are against the null hypothesis that the true AUC is 0.5. P values below 0.05 were considered statistically significant for all performed tests.

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