Methods
Retrospective chart review identified 114 consecutive patients without history of AF or prior cardiac surgery who underwent typical CTI dependent AFL ablation between December 2013 to November 2018 who also had a complete preoperative transthoracic echocardiogram, and at least one year of follow-up at our medical center. All available medical records, including baseline characteristics, medication history, ECG, echocardiogram, and electrophysiology study, were reviewed and analyzed by investigators. The HATCH score was derived by calculation of appropriate variables (HTN, Age >75, TIA/CVA, COPD, CHF).7 Valvular pathology was reported to be present if moderate or greater.
Data collection and analysis were performed according to protocols approved by the NYU Langone Health Institutional Review Board. Surface and intracardiac electrograms (ECGs) were digitally recorded and stored (EP Workmate, Abbott Medical, Inc.). All procedures were performed under conscious sedation after exclusion of left atrial thrombus by transesophageal echocardiography. A 7-French 20-pole catheter (Daig DuoDeca 2-10-2, Abbott Medical, Inc.) was used with the distal poles placed within the coronary sinus and the proximal electrodes located along the tricuspid annulus in the lateral and inferior right atrium. The diagnosis of CTI dependent AFL was confirmed by entrainment or activation mapping at the discretion of the primary operator. Arrhythmia induction by burst pacing was performed in patients presenting in sinus rhythm. 32 patients were found to have atrial tachycardia as their presenting rhythm. Attempted induction of AF was not routinely performed. The primary goal of the procedure was to create a line of bidirectional conduction block in the CTI. Ablation was performed in each group with a radiofrequency ablation catheter with non-fluoroscopic 3-dimensional mapping (Carto 3, Biosense-Webster, Inc., and NavX, Abbott Medical, Inc.).
Patients were followed for up to 3 years after the date of their procedure. Patient follow-up was censored for the purposes of survival analyses at time of last follow up if less than 3 years after their first procedure. Patients received routine outpatient follow-up at 1 month post-ablation and subsequently at the discretion of their referring cardiologist. Oral anticoagulation was continued for at least 1 month during which a two-week ambulatory arrhythmia monitor was recommended. The primary outcome was survival free of incident atrial fibrillation after CTI dependent AFL ablation. Diagnosis of AF was defined by the presence of AF >30s duration on ambulatory arrhythmia monitor or implanted device, or on 12 lead ECG.
Categorical data were analyzed across the two groups with the chi squared test and were reported as frequencies and percentages. Continuous data were analyzed using the Mann-Whitney U test and were reported as mean + standard deviation. Univariate analyses were performed to evaluate for independent predictors of AF after typical CTI AFL ablation. Univariate and multivariate analyses using the cox proportional hazard model were performed to evaluate the relationship between LAVI and incidence of AF, and multivariate analysis was adjusted for differences in significant baseline characteristics. A p value criteria of < 0.1 was used to determine which covariates could be included in the multivariate analysis. A receiver operating characteristic (ROC) curve was constructed to test the ability of LAVI to predict new-onset AF and identify an optimal cutoff value. Kaplan-Meier analysis was performed with a log-rank test to determine how LAVI related to the cumulative risk of incident AF. A two-sidedP value <0.05 was considered statistically significant. SPSS Statistics software 25.0 (IBM, Armonk, NY) was used for data analysis.