Predictors of late recurrence of atrial fibrillation after catheter ablation
Introduction
Arial fibrillation (AF) is the most common sustained arrhythmia in clinical practice, which is associated with increased risk for heart failure, stroke, and cardiovascular mortality, and its morbidity increase drastically from 3.03‰ to 3.68‰ during 1980–2000 in Americans [1]. Catheter ablation has emerged as an effective therapy for patients with symptomatic and drug-refractory AF. Whereas, not a matter of single or combine multi-procedure of segmental pulmonary vein isolation (SPVI), circumferential pulmonary vein ablation(CPVA), left atrial linear ablation (CPVA plus roof and mitral line), and electrogram-based ablation, the following episodes of AF recurrence after ablation procedure range from 20% to 60% [2], [3], [4]. Therefore, it's important to predict the recurrence of AF after ablation. Although several factors have been reported as predictors, there has been not a consensus. Thereby, this study was designed to investigate the clinical variables predicting the recurrence of AF after catheter ablation.
One hundred eighty-six patients who underwent catheter ablation for symptomatic drug-refractory AF in the Second Affiliated Hospital of Chongqing Medical University were included in this study. The mean age was 55.12 ± 12.06 years, 123(66.13%) cases were male. In the 186 patients, 161 were paroxysmal AF and 25 were non-paroxysmal AF. All patients underwent history acquisition, physical examination, conventional 12-lead ECG, 24 h Holter, exercise stress test, thyroid and hepatic function tests, chest X-ray, and Doppler echocardiogram before recruitment in the study. The exclusion criteria were as follows: (1) patients who had previously received ablation, (2) patients who could not complete the systematic follow-up, (3) age > 75 years or < 18 years, (4) an ejection fraction < 40% (measured by transthoracic echocardiogram), (5) a left atrial diameter (LAD) > 55 mm, and (6) valvular disease requiring surgery. Ultimately 9 patients were excluded and 186 eligible patients were included. All patients provided written informed consent, and the study protocol was approved by the ethics committee of our institute.
Paroxysmal AF is defined as AF terminated spontaneous within 7 days, usually within 48 h. Non-paroxysmal AF included persistent AF which defined as either AF episode longer than 7 days or AF requires termination by cardioversion, and long-standing persistent AF which defined as AF lasted for more than 1 year when it is decided to adopt a rhythm control strategy.
Transesophageal echocardiography was performed before the ablation procedure to confirm absence of atrial thrombi. Oral anticoagulation therapy, if any, was replaced by low-molecular heparin 3–5 days prior to the procedure. This, in turn, was discontinued 4 h before the procedure. The conventional electrophysiological study was performed to exclude supraventricular or ventricular tachycardia for patients with sinus rhythm prior to AF ablation. Ablation was performed using a 3.5-mm irrigated-tip ablation catheter (Navistar, Biosense-Webster) under the guidance of the CARTO system and fluoroscopy. Radiofrequency (RF) energy (Stockert, Biosense-Webster) was delivered up to 30 W with a temperature limit of 45–50 °C, and 60 s for each point.
Ablation procedures were started under AF rhythm in 25 patients with non-paroxysmal AF and in 55 patients with paroxysmal AF, and another 106 patients were performed under sinus rhythm. The steps of ablation procedures were as follows: SPVI or CPVA was firstly performed, the end point was PVs isolation which defined as abolition or dissociation of PV potentials or failure to induced AF during procedural pacing via coronary sinus. If induced AF was sustained ≧ 30 s or AF wasn't terminated spontaneously, left atrial linear ablation was secondly performed at the LA roof and the mitral isthmus, the endpoint of the linear ablation was bidirectional conduction block across the linear lesions. If AF still persisted after the first and second procedure, an additional ablation of the complex fractionated atrial electrogram (CFAE) was performed. CFAE was defined as:(1) short cycle length activity (a fractionation interval less than 50 ms or more than 10 ms shorter than in the surrounding area) (2) centrifugal activation, and (3) continuous activity, [5], [6], [7] the endpoint of CFAE sites ablation was prolongation of local cycle length (fibrillation interval longer than 120 ms), elimination of the CFAEs, or isolation of the local fractionated potentials. If AF coexisted with atrial flutter before ablation or ablation converted AF into AT, then right atrium electrophysiological study and linear ablations (at the superior vena cava and/or cavotricuspid isthmus) or the AT ablation are performed. Finally, if none of the above procedures terminated AF, sinus rhythm was restored by electric cardioversion immediately or 5 days after the procedure.
Patients remained in the hospital under continuous rhythm monitoring for at least 7 days after the ablation procedure. Low-molecular heparin subcutaneous injection was continued, and 3 days later all patients received anticoagulant therapy with aspirin plus clopidogrel for at least 3 months. After 3 months, the need for anticoagulation was assessed according to the presence of risk factors for thromboembolism. Amiodarone was prescribed for all patients with non-paroxysmal AF and the patients with paroxysmal AF but suffered from AF storm after ablation procedure. The regimen was 600 mg/day in the first week, 400 mg/day in the second week and followed by 200 mg/day up to 2 months.
Two thirds of patients for 24 h Holter and one third of patients for 7 days Holter were performed at 1st, 2nd, 3rd, 6th, 9th, 12th, 18th, and 24th month, ECG was performed at twice a month until the end of study. All patients were followed by telephone at intervals of 7 days and visited our outpatient clinic every 15 days for physical and ECG examinations. When the patients had palpitations, dizziness or syncope during the follow-up period, they were advised to contact with their doctors immediately and for blood pressure, ECG and Holter re-examined. AF recurrence was defined as an episode lasting more than 30 s and confirmed by ECG or Holter, including atrial fibrillation and atrial tachyarrhythmia (Ata, atrial flutter and atrial tachycardia).
AF recurrence within 3 months post-ablation was defined as early recurrence, otherwise, it was defined as late recurrence, and delayed cure was defined as AF disappearing despite early recurrence during subsequent follow-up of any AADs.
The clinical variables analyzed in this study include: gender, age, duration of AF history, AF category, hypertension, diabetes mellitus(DM), overweight/obesity, metabolic syndrome(MetS), structural heart disease (include coronary artery disease, hypertensive heart disease, atrial septal defect, hypertrophic cardiomyopathy and alcoholic cardiomyopathy), left atrial diameter (LAD), left ventricular ejection fraction (LVEF), ablation strategy, procedural failure which was defined as without AF termination during ablation or not achieving complete PVs isolation in that parts of patients whose procedures were performed in sinus rhythm, the use of angiotensin-converting enzyme inhibitor (ACEI), angiotensin II receptor blockers (ARB) and β-receptor blocker (β-RB) post-ablation, and early recurrence(ERAF).
According to the World Health Organization criteria [8], overweight/obesity was defined as Body mass index (BMI) ≥ 25 kg/m [2]. According to the guidelines of the National Cholesterol Education Program Adult Treatment Panel III [9], patients with 3 of the following criteria were defined as having MS: (1) waist circumference in male ≧ 90 cm and female ≧ 80 cm, (2) hypertriglyceridemia which means triglycerides ≧ 150 mg/dl, (3) a raise of low high-density lipoprotein cholesterol (LDL) which means LDL ≧ 40 mg/dl in men and ≧ 50 mg/dl in women, (4) blood pressure ≧ 130/85 mm Hg and/or a history of treated hypertension, and (5) impaired glucose tolerance which was defined as glucose ≧ 110 mg/dl and/or a history of diabetes. LAD, LVEF and E/A ratio were obtained from transthoracic echocardiogram using Hewlett Packard Sonos 5500 (Hewlett Packard, Palo Alto, CA, USA). LAD was measured at the LA anteroposterior diameter at end-systole on the M-mode image and LV ejection fraction (EF) was determined by standard volumetric methods.
The continuous variables were expressed as means ± SD and categorical dates as frequency (%). Univariate analysis was performed with Chi-square, Fisher's exact tests for categorical data and Student's t tests for continuous data. The parameters with P < 0.10 in the univariate models were selected to be tested in the multivariate analysis (logistic regression analysis). A two-sided P < 0.05 was considered to indicate statistical significance. All statistical analysis were performed using SPSS statistical software (Version 17.00; SPSS Inc, Chicago, IL, USA).
Section snippets
Outcome of catheter ablation
The clinical characteristics of the 186 patients are displayed in Table 1. The mean duration of AF history (months), LAD (mm), and LVEF (%) were 64.52 ± 58.49, 34.97 ± 5.84, and 68.72 ± 8.83, respectively. Yet, only 32(17.20%) patients' LAD was more than 40 mm, and only 31(16.7%) patients' LVEF was less than 60%. Smoking, hypertension, DM, overweight/obesity, and MetS were present in 32.26%, 34.41%, 10.22%, 28.49%, and 32.80% of patients, respectively. Structural heart disease including coronary
Main finding
To our knowledge, this is the first article that comprehensive assay of the predictors for AF recurrence is discussed. The results demonstrated that MetS, overweight/obesity, procedural failure and ERAF are independent predictors for LRAF after catheter ablation. Furthermore, Ata plays an important role in both ERAF and LRAF.
MetS and LRAF
MetS was a risk factor of new-onset of AF, [10], [11] besides it was an independent predictor for AF recurrence after catheter ablation [12]. Chang et al. [13] reported
Limitation
One limitation is that this study includes a relatively small number of patients. Second, some asymptomatic recurrence may be undetected without the use of long-term recording, [2], [38] besides, the follow-up period is not long enough that some very late recurrence (recurrence after 2 years of the ablation procedure) may be ignored [39]. Therefore, the AF recurrence maybe underestimated and some underlying risk factors may be neglected or less studies. Third, the precise mechanisms responsible
Conclusion
This study demonstrates that overweight/obesity, metabolic syndrome, procedural failure, and ERAF are independent predictors for late recurrence of atrial fibrillation. In clinic practice, the presence of overweight/obesity and metabolic syndrome should be considered in the assessment of patients amenable to AF catheter ablation.
Conflict of interest
None declared.
Acknowledgment
The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology.
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Drs. Cai and Yin have same contribution to this paper.