Cavotricuspid isthmus (CTI) ablation is a highly effective treatment of typical atrial flutter (AFL). The emergence of new-onset atrial fibrillation (AF) following CTI ablation is clinically relevant but limited data exist regarding its predictors. The goal of this study is to investigate predictors of new-onset AF following CTI ablation. Patients who underwent CTI ablation between 2016 and 2022 were included. Baseline variables including left atrial volume index (LAVI), cardiac comorbidities, CHA₂DS₂-VASc score, and medications were collected. The primary outcome was the occurrence of new-onset AF after the index CTI ablation. New AF occurred in 44 (29%) of 153 patients at a median of 264 days. Patients who developed AF were more likely men (p = 0.046), had hypertension (p = 0.014), and higher LAVI (40.6 ± 12.2 vs 34.2 ± 9.5 mL/m², p <0.001). After adjusting for unbalanced covariates in a Cox multivariable model, protective predictors against developing new AF included female sex (HR 0.31, 95% CI 0.12–0.76, p = 0.011) and prior cardiac surgery (HR 0.22, 95% CI 0.07–0.72, p = 0.013) while increased LAVI (HR 1.02, 95% CI 1.00–1.05, p = 0.08) showed a trend towards higher risk of new AF. In conclusion, in this cohort of AF-naive patients undergoing CTI ablation for typical AFL, nearly one-third developed new-onset AF. Independent predictors of developing AF include male sex and no-prior cardiac surgery. These findings have clinical implications to the management of AFL patients, including for the decision to consider performing concomitant AF ablation in patients with higher risk features.
Cavotricuspid isthmus ablation (CTI) is a highly effective treatment for restoring normal rhythm in patients with AFL. Unfortunately, a significant subset of patients may develop new-onset atrial fibrillation (AF) following the procedure, with incidence ranging between 30% to 80%. ,,,, AF occurrence after successful CTI ablation for atrial flutter (AFL) is associated with worse quality of life. Although the exact mechanisms leading to the development of AF post CTI ablation are not clear, few risk factors have been proposed including higher CHA 2 DS 2 -VASC scores and left atrial (LA) volumes. , A better understanding of the predictors of AF incidence after CTI ablation is crucial for tailoring management strategies in select patients. The goal of the present study is therefore to analyze systematically the key demographic, clinical, and echocardiographic variables that are associated with AF development following successful CTI ablation of AFL.
Methods
The protocol for this study was approved by the institutional review board of the Medical College of Georgia, who waived the need to obtain written informed consent due to the retrospective and observational nature of this analysis. We included 156 patients who were referred from the hospital services or the outpatient cardiology clinics to the EP service and underwent successful CTI ablation for AFL between April 2016 and November 2022. Patients with a prior history of AF were excluded. CTI ablation was performed in all patients under general anesthesia, with contact force 3D mapping, and intra-cardiac echo guidance. Patients were followed to the primary outcome of AF development following CTI ablation or to the last day of follow-up, through March of 2024.
Patient demographics, clinical history, and echocardiographic parameters were abstracted from the institutional electronic health records. These included patients age, body mass index, left atrial volume index (LAVI), left ventricular ejection fraction (LVEF), and the CHA₂DS₂-VASC score. The time from CTI ablation to first AF diagnosis was also recorded.
All analyses were conducted using SPSS statistical software (version 27, IBM Inc., Armonk, NY) and open-source Python programming (version 3.10.12, Python Software Foundation, Wilmington, Delaware). Categorical variables are reported as counts and percentages and compared using the chi-square test. Continuous variables are reported as mean ± standard deviation or as median and interquartile range and are compared using the student t test Mann-Whitney U test, as appropriate. Univariable predictors of new AF occurrence after successful CTI ablation in AF-naïve patients were determined using cox models with time to AF as the primary outcome. Age and all variables that achieved a p <0.10 on univariable testing were included in the multivariable Cox model, to identify independent predictors of AF in this population. All variables were reported with hazard ratios (HR) and 95% confidence intervals (95% CI). Two-sided p values <0.05 were considered statistically significant.
Results
Of the total of 156 patients who underwent CTI ablation for typical AFL and who were included in this analysis, 3 patients were lost to follow-up and were excluded from this analysis ( Figure 1 ). Of the remaining 153 patients, 44 (29%) developed AF at a median time of 264 days (interquartile range 55–584 days). The time to incident AF after CTI ablation is shown in Figure 2 . The mean age of the overall cohort was 62 ± 12 (range 22–88) years and 28% of patients were women. Table 1 details the baseline characteristics of all patients in the cohort, stratified by the incidence of AF during follow-up. Patients with AF following CTI ablation trended towards being older with higher prevalence of hypertension. They were also more likely to be men, with increased LAVI, and were less likely to have undergone prior cardiac surgery. Of note, the LVEF was reduced (<50%) in many patients in our study population (n = 82, 54%), with no differences between patients who did versus those who did not develop AF during follow-up.
Consort diagram of the study.
Histogram of incident atrial fibrillation by 100-day bins after cavotricuspid isthmus ablation for typical atrial flutter.
Table 1
Baseline characteristics of the overall cohort, stratified by incidence of AF
| Overall | AF | No AF | p value | |
|---|---|---|---|---|
| N | 153 | 44 | 109 | – |
| Age (years) | 62 ± 12 | 63 ± 10 | 61 ± 13 | 0.23 |
| Women | 43 (28%) | 7 (16%) | 36 (33%) | 0.046 |
| Body mass index (kg/m 2) | 31 ± 8 | 32 ± 7 | 31 ± 8 | 0.35 |
| CHA 2 DS 2 -VASC score | 2.7 ± 1.4 | 2.9 ± 1.4 | 2.6 ± 1.4 | 0.22 |
| Hypertension | 115 (75%) | 36 (82%) | 76 (70%) | 0.014 |
| Diabetes mellitus | 58 (38%) | 17 (39%) | 41 (38%) | 1.00 |
| Cerebrovascular accident | 11 (7%) | 4 (9%) | 7 (6%) | 0.73 |
| Coronary artery disease | 47 (31%) | 15 (34%) | 32 (29%) | 0.57 |
| Obstructive sleep apnea | 45 (29%) | 15 (34%) | 30 (27%) | 0.44 |
| Prior cardiac surgery | 24 (16%) | 3 (7%) | 21 (19%) | 0.08 |
| Left ventricular ejection fraction (%) | ||||
| Mean | 36 ± 25 | 40 ± 23 | 34 ± 26 | 0.21 |
| Median | 42 (1- 57) | 50 (24–57) | 40 (1–59) | 0.45 |
| Left atrial volume index (mL/m 2) | 36 ± 11 | 41 ± 12 | 34 ± 9 | <0.001 |
| Mitral regurgitation grade | 1.0 ± 0.4 | 1.0 ± 0.6 | 1.0 ± 0.5 | 0.83 |
| Use of beta blockers | 109 (71%) | 36 (82%) | 73 (67%) | 0.08 |
| Use of anti-arrhythmic drugs | 11 (7%) | 4 (9%) | 7 (6%) | 0.73 |
| Duration of atrial flutter (months) | 9.6 ± 28.8 | 6.6 ± 12.3 | 10.9 ± 33.2 | 0.70 |
Of the 44 patients who developed AF in follow-up, 19 (43%) underwent AF ablation, 2 had a maze surgery, and 3 underwent electrical cardioversion. Patients had their AF ablation at a median time of 62 days after the CTI ablation (interquartile range 29–95 days).
Univariable Cox analysis was performed to identify predictors of AF occurrence post-CTI ablation. As shown in Table 2 , AF incidence was significantly higher in men, in patients with increased LAVI, and tended to be higher in patients with hypertension. Using multivariable Cox hazard model, independent predictors of AF occurrence included male sex ( Figure 3 A) and no prior history of cardiac surgery ( Figure 3 B). A higher LAVI showed an association with AF occurrence, but this did not reach statistical significance.
Table 2
Univariable and multivariable Cox regression analyses of predictors for atrial fibrillation (AF) developing after successful cavotricuspid isthmus ablation of atrial flutter
| p | HR | 95% CI | p | HR | 95% CI | |||
|---|---|---|---|---|---|---|---|---|
| Lower | Upper | Lower | Upper | |||||
| Age | 0.30 | 1.01 | 0.99 | 1.04 | 0.72 | 1.00 | 0.98 | 1.03 |
| Sex (female) | 0.025 | 0.39 | 0.18 | 0.89 | 0.011 | 0.31 | 0.12 | 0.76 |
| Body mass index | 0.42 | 1.01 | 0.98 | 1.05 | ||||
| CHA 2 DS 2 -Vasc Score | 0.49 | 1.08 | 0.87 | 1.33 | ||||
| Hypertension | 0.08 | 2.33 | 0.92 | 5.92 | 0.87 | 1.09 | 0.40 | 2.94 |
| Diabetes mellitus | 0.89 | 0.96 | 0.92 | 1.77 | ||||
| Cerebrovascular disease | 0.73 | 1.20 | 0.42 | 3.47 | ||||
| Coronary artery disease | 0.89 | 0.96 | 0.51 | 1.79 | ||||
| Obstructive sleep apnea | 0.49 | 1.25 | 0.67 | 2.34 | ||||
| Prior cardiac surgery | 0.024 | 0.26 | 0.08 | 0.84 | 0.013 | 0.22 | 0.06 | 0.72 |
| Left ventricular ejection fraction | 0.77 | 1.00 | 0.99 | 1.01 | ||||
| Left atrial volume index | 0.045 | 1.02 | 1.00 | 1.05 | 0.077 | 1.02 | 1.00 | 1.05 |
| Duration of atrial flutter | 0.57 | 0.99 | 0.98 | 1.01 | ||||
| Use of antiarrhythmic drugs | 0.31 | 1.71 | 0.61 | 4.80 | ||||
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