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.