Similar predisposing factors are found in most types of atrial arrhythmias. The incidence of atrial fibrillation (AF) among patients with atrial flutter is high, suggesting similar outcomes in patients with those arrhythmias. We sought to investigate the long-term outcomes and prognostic factors of patients with AF and/or atrial flutter with contemporary management using radiofrequency ablation. In an academic institution, we retrospectively examined the clinical course of 8,962 consecutive patients admitted to our department with a diagnosis of AF and/or atrial flutter. After a median follow-up of 934 ± 1,134 days, 1,155 deaths and 715 stroke and/thromboembolic (TE) events were recorded. Patients with atrial flutter undergoing cavotricuspid isthmus ablation (n = 875, 37% with a history of AF) had a better survival rate than other patients (hazard ratio [HR] 0.35, 95% confidence interval [CI] 0.25 to 0.49, p <0.0001). Using Cox proportional hazards model and propensity score model, after adjustment for main other confounders, ablation for atrial flutter was significantly associated with a lower risk of all-cause mortality (HR 0.55, 95% CI 0.36 to 0.84, p = 0.006) and stroke and/or TE events (HR 0.53, 95% CI 0.30 to 0.92, p = 0.02). After ablation, there was no significant difference in the risk of TE between patients with a history of AF and those with atrial flutter alone (HR 0.83, 95% CI 0.41 to 1.67, p = 0.59). In conclusion, in patients with atrial tachyarrhythmias, those with atrial flutter with contemporary management who undergo cavotricuspid isthmus radiofrequency ablation independently have a lower risk of stroke and/or TE events and death of any cause, whether a history of AF is present or not.
Highlights
- •
The impact of catheter ablation for typical atrial flutter on mortality and thromboembolic events is poorly known.
- •
In patients with atrial arrhythmias, we found a lower mortality in patients with ablation for atrial flutter, even after adjusting for confounding factors.
- •
Atrial flutter with cavotricuspid isthmus ablation was also associated with a lower risk of stroke.
- •
These findings were similar in patients with atrial flutter and a history of atrial fibrillation.
- •
Ablation for atrial flutter is thus effective to maintain sinus rhythm and likely to be associated with a better prognosis on clinical end points.
Cavotricuspid isthmus (CTI)–dependent atrial flutter is a frequent arrhythmia involving a single macroreentrant circuit with activation in the right atrium around the tricuspid valve annulus, classically in a counterclockwise direction. Atrial flutter is associated with the same complications as atrial fibrillation (AF), especially the risk of thromboembolic (TE) events or developing tachycardiomyopathy. Over the years, CTI radiofrequency (RF) ablation has demonstrated to be a safe and effective alternative to antiarrhythmic drug treatment and is now recommended as first-line therapy for this arrhythmia. Similar predisposing factors are found in most types of atrial arrhythmias, including age, male gender, diabetes, congestive heart failure, or chronic pulmonary disease. The incidence of AF among patients with a previous atrial flutter episode is very high, around 25 times higher than in the general population of the same age, suggesting similar outcomes and complication rates in patients with atrial flutter and AF, whether CTI RF ablation is performed or not. However, as limited data are available, this study sought to investigate the long-term outcomes and prognostic factors of patients with contemporary management of atrial flutter.
Methods
All patients admitted to our cardiology department with a diagnosis of AF and/or atrial flutter from January 1, 2000, to December 31, 2010, were retrospectively included. Prespecified subgroups were defined: group 1 consisted of all patients undergoing CTI RF ablation for atrial flutter (group 1A: atrial flutter only and group 1B: atrial flutter and a history of AF) and group 2 consisted of all other patients with AF and/or atrial flutter, without ablation. Patients were selected in the hospital discharge records, and extensive information on date of admission, discharge, diagnosis, clinical presentation, co-morbidities, performed procedures, medication, subsequent hospitalization, adverse events, and in-hospital death were collected. The CHA 2 DS 2 -VASc and HAS-BLED scores were calculated for each patient. History of AF was defined as the presence of any documented AF tracing before ablation. Stroke and/or TE events and all-cause mortality were then collected for all patients until December 31, 2010. AF was defined on the electrocardiogram by the replacement of consistent P waves by rapid oscillations or fibrillatory waves that vary in amplitude, shape, and timing, associated with an irregular frequently rapid ventricular response when atrioventricular conduction was intact. CTI-dependent form of atrial flutter was suspected on the electrocardiogram by the presence of a typical pattern of regular atrial activation (flutter waves), particularly visible in leads II, III, aVF, and V 1 , the atrial rate typically ranging from 240 to 320 beats/min.
Electrophysiological study was systematically performed whenever CTI-dependent atrial flutter was suspected on the electrocardiogram, as previously described, whether in a typical counter clockwise or a clockwise form. Written informed consent was obtained for all patients, and the ablation procedure was performed under conscious sedation. For elective procedures, antiarrhythmic drugs were discontinued at least 5 half-lives before ablation, and oral anticoagulants were discontinued 48 hours before the procedure, to obtain an international normalized ratio ≤2.0. Transesophageal echocardiography was performed before ablation in patients with insufficient anticoagulation to exclude the presence of atrial thrombi. Two 8Fr sheaths were introduced into the femoral vein. A 7Fr duodecapolar catheter was placed into the right atrium with the proximal bipole in the upper region of the right atrium, the bipole 11-12 on the lateral side of the right atrium, and the distal bipole in the proximal coronary sinus. An 8-mm nonirrigated ablation catheter was used for mapping and ablation. For patients with spontaneous arrhythmia, activation mapping within the right atrium was performed to confirm typical flutter: counterclockwise or clockwise activation around the tricuspid annulus. CTI dependence was confirmed by entrainment mapping in the CTI and postpacing interval measurement with subsequent CTI RF ablation. In patients in sinus rhythm and documented typical atrial flutter tracings, CTI RF ablation was performed during atrial pacing from the coronary sinus. Radiofrequency application was performed (60 W, 60°C), by either continuous dragging or selectively targeting sites with high-amplitude signals. Bidirectional block was verified by pacing on both sides of the ablation line, with demonstration of activation detour using signals recorded on the duodecapolar catheter. Additional pacing maneuvers and mapping were used to confirm the ablation end point in questionable cases. Ablation was considered successful when bidirectional isthmus block persisted at least 20 minutes.
After catheter ablation, patients underwent follow-up by the referring cardiologist at least every 12 months. Monitoring at follow-up visits included a 12-lead electrocardiography to document the rhythm and rate and, for those on antiarrhythmic drug therapy, to assess potential proarrhythmic electrocardiographic precursors, nonsustained ventricular tachycardia, or pauses. Long-term electrocardiographic recordings were not systematic and were performed when decided by the cardiologist if any worsening of symptoms or unexplained symptoms occurred. Patients were censored at the time of last known follow-up. During follow-up, study outcomes (TE event, stroke, and all-cause mortality) were recorded using International Classification of Diseases, Tenth Revision , in the hospital coding system and information collected until December 31, 2010. The institution includes a total of 4 hospitals covering all specialties and is the only public institution in an area of around 4,000 km 2 , serving approximately 400,000 inhabitants. Death was also recorded using a search tool on a Web site dedicated to local news covering 35,000 km 2 ( http://nrco.lanouvellerepublique.fr/dossiers/necro/index.php ).
All data were analyzed using StatView, version 5.0 (SAS Institute Inc., Cary, North Carolina). Descriptive statistics of patients’ baseline parameters are reported as mean value ± SD for normally distributed continuous variables. An unpaired Student t test was used for comparison of characteristics among groups. Survival from any stroke and/or TE event and death of any cause was calculated with the Kaplan-Meier method. Comparison among groups was performed using the log-rank test. The Cox proportional hazard model was used for univariate and multivariate analyses to determine the independent predictive factors associated with different outcomes in the overall population. The results are expressed as hazard ratios and 95% confidence intervals. In addition, we estimated a propensity score model. The individual propensities for having CTI RF ablation for atrial flutter were estimated using logistic regression using a list of potential confounders provided in Table 1 . A p value of ≤0.05 was considered significant. No extramural funding was used to support this work.
| Variable | Group 1A (n = 550) | Group 1B (n = 325) | p ∗ | Group 2 (n = 8,087) | p † |
|---|---|---|---|---|---|
| Age (years) | 67 ± 12 | 64 ± 12 | 0.001 | 71 ± 15 | <0.0001 |
| Men | 456 (83%) | 254 (78%) | 0.08 | 4,785 (59%) | <0.0001 |
| History of atrial fibrillation | 0 (0%) | 325 (100%) | — | 8,087 (100%) | <0.0001 |
| Heart failure | 274 (50%) | 147 (45%) | 0.19 | 4,491 (56%) | <0.0001 |
| Hypertension | 204 (37%) | 120 (37%) | 0.96 | 3,419 (42%) | 0.003 |
| Diabetes mellitus | 100 (18%) | 37 (11%) | 0.008 | 1,249 (15%) | 0.87 |
| Prior stroke | 20 (4%) | 19 (6%) | 0.13 | 699 (9%) | <0.0001 |
| Coronary artery disease | 128 (23%) | 64 (20%) | 0.22 | 2,526 (31%) | <0.0001 |
| Previous myocardial infarction | 42 (8%) | 30 (9%) | 0.41 | 1,226 (15%) | <0.0001 |
| Valvular heart disease | 85 (15%) | 49 (15%) | 0.88 | 1,905 (24%) | <0.0001 |
| Thyroid disorder | 14 (3%) | 19 (6%) | 0.01 | 664 (8%) | <0.0001 |
| Renal failure | 35 (6%) | 11 (3%) | 0.06 | 762 (9%) | <0.0001 |
| Previous major bleeding | 23 (4%) | 10 (3%) | 0.40 | 451 (6%) | 0.02 |
| Pacemaker or defibrillator | 66 (12%) | 35 (11%) | 0.58 | 1,403 (17%) | <0.0001 |
| LVEF (%) (n = 2,114) ‡ | 43 ± 16 | 49 ± 15 | 0.02 | 47 ± 16 | <0.0001 |
| Creatinine (μmol/L) (n = 7,569) ‡ | 111 ± 57 | 110 ± 50 | 0.31 | 110 ± 50 | 0.55 |
| CHA 2 DS 2 -VASc score | 2.3 ± 1.6 | 2.1 ± 1.7 | 0.08 | 3.3 ± 1.8 | <0.0001 |
| HAS-BLED score | 1.3 ± 1.0 | 1.1 ± 1.0 | 0.06 | 1.6 ± 1.1 | <0.0001 |
| Duration of follow-up (days) | 713 ± 921 | 1016 ± 1153 | <0.0001 | 940 ± 1087 | 0.003 |
| Therapy at discharge or during follow-up: | |||||
| Oral anticoagulation (n = 8,051) ‡ | 388 (74%) | 251 (82%) | 0.01 | 3,998 (55%) | <0.0001 |
| Antiplatelet agent (n = 8,051) ‡ | 143 (28%) | 63 (21%) | 0.02 | 2,555 (36%) | <0.0001 |
| ACE-I (n = 4,938) ‡ | 187 (36%) | 91 (28%) | 0.02 | 1,697 (42%) | <0.0001 |
| Beta-blocker (n = 4,938) ‡ | 171 (33%) | 127 (39%) | 0.05 | 1,876 (46%) | <0.0001 |
| Antiarrhythmic agent (n = 6,009) ‡ | 114 (22%) | 122 (38%) | <0.0001 | 1,901 (37%) | 0.02 |
| Digoxin (n = 4,476) ‡ | 28 (5%) | 34 (10%) | 0.005 | 1,290 (31%) | <0.0001 |
| Diuretics (n = 4,476) ‡ | 99 (45%) | 45 (31%) | 0.008 | 1,981 (48%) | 0.001 |
| Cardioversion | 14 (3%) | 24 (7%) | 0.0007 | 918 (11%) | <0.0001 |
| Ablation for atrial fibrillation | 0 (0%) | 60 (18%) | — | 196 (2%) | <0.0001 |
∗ Comparison between groups 1A and 1B.
† Comparison between group 1 (groups 1A and 1B) and group 2.
‡ Number of patients with available data on the studied parameter.
Results
A total of 8,962 patients with AF and/or atrial flutter were included in this study. There were 875 patients with atrial flutter who underwent CTI RF ablation (group 1). Forty-four patients (5%) had a clockwise form of CTI-dependent flutter. Bidirectional block after CTI RF ablation was obtained in 860 patients (98.3%). There were 325 patients (37%) who had a history of AF before CTI RF ablation (group 1B). Characteristics of all the patients included in the study are listed in Table 1 . Patients in group 1B were younger than those in group 1A and were more likely to be treated with anticoagulation and antiarrhythmic agents. Patients in group 2 were significantly less likely to be men; had a greater prevalence of congestive heart failure, hypertension, coronary artery disease and previous myocardial infarction, valvular heart disease, a previous stroke event, chronic renal failure, and a previous bleeding event; and had therefore higher CHA 2 DS 2 -VASc and HAS-BLED scores. Patients in group 1 were more likely to receive oral anticoagulation and less likely to receive β blockers.
The perioperative complication rate in group 1 after CTI RF ablation was 0.46%, including 1 tamponade necessitating a surgical drainage and 3 significant groin hematomas, of which one necessitated a surgical treatment. No stroke and/or TE event or death was directly related to the procedure. After a median follow-up of 929 ± 1,082 days, episodes of AF were documented in 35% of the patients with CTI RF ablation. AF episodes occurred in 48% of the patients who had a preablation history of AF and in 28% who had none (p <0.0001).
During follow-up, 715 strokes or TE events occurred ( Table 2 ). Risk of stroke and/or TE events was significantly less in group 1 versus group 2. In group 1, there was no difference in the rate of TE events between patients with and without a history of AF ( Figure 1 ). In multivariate analyses, among the CHA 2 DS 2 -VASc score items, 4 were associated with a significantly greater risk of stroke and/or TE events, the presence of previous stroke being associated with the highest risk ( Table 2 ). Catheter ablation of atrial flutter was independently associated with a 47% lower risk of stroke and/or TE events (95% confidence interval 0.30 to 0.92). The rate of TE events seemed more markedly reduced in patients of group 1 at low risk of stroke (CHA 2 DS 2 -VASc score of ≤1) compared with patients of group 2 with the same score ( Table 3 ). The lower risk was still significant after adjustment for warfarin use.
| Univariate Analysis | Multivariate Analyses | |||
|---|---|---|---|---|
| Hazard Ratio (95% CI) | p | Hazard Ratio (95% CI) | p | |
| Stroke/thromboembolic events (n = 715) | ||||
| Age | 1.05 (1.04–1.05) | <0.0001 | 1.04 (1.03–1.05) | <0.0001 |
| Male sex | 0.80 (0.69–0.93) | 0.004 | 1.06 (0.85–1.31) | 0.61 |
| Diabetes mellitus | 1.33 (1.10–1.61) | 0.002 | 1.46 (1.14–1.87) | 0.003 |
| Hypertension | 1.38 (1.20–1.60) | 0.002 | 0.94 (0.77–1.16) | 0.59 |
| Heart failure | 1.42 (1.21–1.65) | <0.0001 | 1.58 (1.20–2.10) | 0.001 |
| Coronary artery disease | 1.29 (1.11–1.51) | 0.0009 | 1.12 (0.85–1.46) | 0.41 |
| Previous myocardial infarction | 1.30 (1.07–1.56) | 0.006 | 0.95 (0.69–1.32) | 0.77 |
| Chronic pulmonary disease | 1.16 (0.94–1.45) | 0.16 | 1.08 (0.82–1.42) | 0.58 |
| Renal failure | 1.40 (1.12–1.76) | 0.003 | 0.98 (0.73–1.32) | 0.91 |
| Prior stroke | 3.66 (4.36–3.07) | <0.0001 | 3.26 (2.56–4.13) | <0.0001 |
| Pacemaker or defibrillator | 0.89 (0.75–1.07) | 0.24 | 0.78 (0.62–1.01) | 0.06 |
| Atrial flutter and CTI RF ablation | 0.44 (0.31–0.64) | <0.0001 | 0.53 (0.30–0.92) | 0.02 |
| Atrial flutter and history of AF | 0.54 (0.33–0.89) | 0.17 | 1.47 (0.71–3.05) | 0.30 |
| Failure to obtain complete CTI block | 1.15 (0.28–4.60) | 0.84 | 1.67 (0.40–6.99) | 0.48 |
| Vitamin K antagonist at discharge | 0.84 (0.72–0.98) | 0.03 | 0.90 (0.71–1.13) | 0.35 |
| Antiplatelet agent at discharge | 1.52 (1.30–1.79) | <0.0001 | 1.09 (0.86–1.40) | 0.47 |
| ACE inhibitor at discharge | 1.26 (1.04–1.52) | 0.15 | 1.10 (0.90–1.35) | 0.35 |
| Beta blocker at discharge | 0.95 (0.78–1.15) | 0.61 | 0.92 (0.75–1.13) | 0.42 |
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
