2023 Volume 87 Issue 12 Pages 1742-1749
Background: There are limited data about predictors of atrial fibrillation (AF) recurrence after totally thoracoscopic ablation (TTA). This study investigated the clinical implication of left atrial appendage emptying velocity (LAAV) in patients undergoing TTA.
Methods and Results: Patients who underwent TTA between 2012 and 2015 at a tertiary hospital were prospectively enrolled in this study. LAAV was measured and averaged over five heart beats from preoperative transesophageal echocardiography. The primary outcome was a freedom from recurrent AF or atrial flutter (AFL) detected on 24-h Holter monitoring or an electrocardiogram over a 3-year period after TTA. In all, 129 patients were eligible for analysis in this study. The mean (±SD) patient age was 54.4±8.8 years, and 95.3% were male. During the 3 years after TTA, the overall event-free survival rate was 65.3%. LAAV was an independent predictor of recurrent AF/AFL during the 3-year period after TTA (per 1-cm/s increase, adjusted hazard ratio [aHR] 0.95; 95% confidence interval [CI] 0.91–0.99; P=0.016). Event-free survival was significantly lower among patients with a low LAAV (<20 cm/s; n=21) compared with those with a normal (≥40 cm/s; n=38; aHR 6.11; 95% CI 1.42–26.15; P=0.015) or intermediate (LAAV ≥20 and <40 cm/s; n=70; aHR 2.74, 95% CI 1.29–5.83; P=0.009) LAAV.
Conclusions: In patients with AF, LAAV was significantly associated with the risk of long-term recurrence of AF after TTA.
Current guidelines recommend surgical ablation in patients who have symptomatic atrial fibrillation (AF) refractory or intolerant to antiarrhythmic drug therapy.1 The traditional Maze operation is a highly invasive procedure in patients not planned for cardiac surgery or a concomitant cardiac procedure. Totally thoracoscopic ablation (TTA) is a video-assisted minimally invasive surgery that does not use cardiopulmonary bypass. Favorable outcomes have been reported following TTA.2–5 Despite being minimally invasive, TTA carries the risk of surgical complications, with reported recurrence rates of up to 67% at 1 year.4–7 Therefore, selecting an appropriate surgical candidates based on outcome predictions is important, but there are limited data available. A single-center study reported that a larger left atrial (LA) diameter was related to AF recurrence after TTA.3 Although that finding is physiological, the optimal cut-off value for LA diameter is unclear and more practical parameters for clinicians are still needed.
Previous studies suggested that structural remodeling of the LA is closely related to the severity and persistence of AF.8–10 Among several diagnostic tools for evaluating AF, LA appendage emptying velocity (LAAV) measured by transesophageal echocardiography (TEE) may serve as a surrogate of LA function.11 In patients with AF, LAAV predicts future embolic events12 and is a known prognostic indicator of the maintenance of sinus rhythm after successful electrical cardioversion13,14 or catheter ablation.15 In the present study, we sought to investigate the clinical and prognostic implications of the LAAV in patients undergoing TTA.
Between February 2012 and March 2015, consecutive patients undergoing TTA were enrolled in a prospective registry in Samsung Medical Center, Republic of Korea. Patients with AF refractory to at least 1 antiarrhythmic drug or electrical cardioversion were candidates for TTA. TTA was contraindicated in patients with LA thrombi or intolerance to one-lung ventilation.2,16
Of the 150 consecutive patients who underwent TTA during the study period, 21 were excluded for the following reasons: they did not undergo an adequate surgical procedure due to a huge LA (1 patient), severe pericardial adhesion (2 patients), or planned LA appendage (LAA) resection alone for stroke prevention (1 patient); or they did not undergo LAA resection during surgery (17 patients). This left 129 patients who were eligible for analysis in the present study (Figure 1). Eligible patients were divided into 3 groups according to the LAAV as follows: low (LAAV <20 cm/s), intermediate (LAAV ≥20 and <40 cm/s), and normal (LAAV ≥40 cm/s).13,14,17
Study population. LA, left atrium; LAA, left atrial appendage.
Procedures were performed in accordance with the Declaration of Helsinki and the ethical standards of the institutional committee responsible for human experimentation.
Surgical ProcedureTransthoracic echocardiography, TEE, and chest computed tomography (CT) were performed in all patients preoperatively. After induction of general anesthesia and double-lumen endotracheal intubation, selective ventilation of the contralateral lung was performed. TTA is a video-assisted thoracoscopic surgical technique without thoracotomy and cardiopulmonary bypass. A bilateral approach is required, and the detailed techniques of TTA have been described in our previous report.16 Ablation lines for pulmonary vein isolation were created using an AtriCure Isolator Transpolar Clamp (AtriCure, Inc., Cincinnati, OH, USA) and LA roof and floor lesions connecting both pulmonary veins were created with a linear pen device (AtriCure, Inc.). After isolation of the pulmonary vein and the creation of box lesions, an exit and entrance block test was performed using an AtriCure Cooltip pen. Next, the ganglionated plexuses were checked and ablated. The ligament of Marshall, which may be a source of adrenergic atrial tachycardia, was always divided and ablated. The LAA was removed by stapling with an Echelon Flex 60 articulating endoscopic linear stapler (Ethicon Endo-Surgery Inc., Cincinnati, OH, USA).
Basically, our strategy was a hybrid procedure: complete ablation on both the epicardial and endocardial ablation sides. Early on, we used to perform a routine postprocedural electrophysiologic study followed by cavotricuspid isthmus ablation before discharge; however, based on our previous experience,18,19 we currently perform an electrophysiologic study including touch-up ablations under the guidance of a 3-dimensional mapping system only in patients with atrial tachyarrhythmia refractory to thoracoscopic epicardial ablation after 3 months.20
Postoperative Care and Follow-upPatients were monitored in the intensive care unit for the first 24 h after the procedure. Heparin was administered after 2 h postoperatively and conversion to either warfarin or a non-vitamin K oral anticoagulant was done as soon as possible. Oral amiodarone was prescribed if the heart rate was >80 beats/min with AF rhythm at rest. Patients were followed up at 3, 6, and 12 months, and at least annually thereafter. Antiarrhythmic drugs were discontinued after 3 months or up to 6 months based on the results of 24-h Holter monitoring. Anticoagulants were also discontinued after 3 months considering the risk of stroke for each patient.
Recurrent AF or atrial flutter (AFL) was defined as any AF or AFL detected on an electrocardiogram (ECG) or lasting more than 30 s on 24-h Holter monitoring. An ECG was performed at each visit, and 24-h Holter monitoring was performed annually unless the patient refused. In case of recurrence, rhythm control including electrical cardioversion and catheter ablation was attempted with antiarrhythmic drugs.
Histological AnalysisA portion of each LA tissue (ranging in size from ~2 mm×4 mm to 4 mm×10 mm) was fixed in 10% buffered formalin and embedded in paraffin. To quantify the extent of atrial fibrosis, 5-μm sections stained with Picro Sirius red were scanned (×400) and the percentage fibrotic area was automatically measured using the Image Pro Plus program (Media Cybernetics, Inc., Bethesda, MD, USA). Because automatic measurement of myocardial fibrosis tends to overestimate the real pathologic sclerotic tissue, we excluded non-pathologic fibrosis areas such as peri-adventitial and adipose tissue, and tangentially cut subendocardial portions. Mean values of 5 random fields from each slide were calculated in 24 randomly selected patients.21
EchocardiographyBefore TTA in all patients, comprehensive transthoracic echocardiography and TEE were performed using commercially available equipment (for TEE, EPIQ CVx [Philips Medical System, Andover, MA, USA]) according to the practice guideline.22 The average of 5 consecutive Doppler signals was used for all patients. All values were calculated from a cardiac cycle with a heart rate <110 beats/min to avoid inadequate LA emptying or filling.
Left ventricular end-diastolic and end-systolic diameter and the LA diameter were calculated from the parasternal long-axis view. The left ventricular ejection fraction was calculated from 2-dimensional recordings using the modified biplane Simpson’s method. LA volume was assessed by the modified biplane area-length method and was indexed to body surface area. Early diastolic mitral inflow velocity (E) was measured using the pulsed wave Doppler method by placing the sample volume at the level of the mitral valve leaflet tips. The tissue Doppler-derived early diastolic mitral annular velocity (e′) was measured from the septal corner of the mitral annulus in the apical 4-chamber view. Peak longitudinal LA strain (reservoir strain) was measured using vendor-independent dedicated software (2D cardiac Performance Analysis 1.4; TomTec Imaging System) according to the current guideline.23
In TEE, LAAVs were evaluated at 4 different angles (i.e., 0°, 45°, 90°, and 135°). Based on previous practice,22 LAAVs were measured over 5 heart beats using a pulsed wave Doppler within the proximal part of the LAA cavity at each angle. The representative LAAV was set to the average value at the angle from which the maximal velocity appears. The mean diameter of the LAA orifice was calculated as the average of the maximum and minimum diameters.
Cardiac CT ImagingCardiac multidetector CT imaging was performed using a 64-slice scanner (Aquilion 64; Toshiba Medical Systems, Otawara, Japan) according to the standardized clinical protocol. All examinations were ECG-gated, and were conducted after administration of 50–80 mL non-ionic iopromide contrast medium (Ultravist; Bayer, Leverkusen, Germany) at a rate of 4–6 mL/s. The LAA morphology was categorized as windsock, chicken wing, cactus, or cauliflower based on the previous classifications of Kimura et al.24
Statistical AnalysisCategorical variables are presented as frequencies and percentages, and were compared using the Chi-squared test or Fisher’s exact test. Continuous variables are presented as the mean±SD or median with interquartile range (IQR), and were compared using analysis of variance (ANOVA) or the Kruskal-Wallis test. The primary outcome was freedom from AF (including AFL) recurrence, detected on ECG or lasting more than 30 s in 24-h Holter monitoring, over a 3-year period after TTA. Cumulative event rates were estimated using the Kaplan-Meier method and compared using a log-rank test. Cox proportional hazards regression was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) between groups. Variables presenting differences between groups with P<0.1 and clinically relevant variables such as age, CHA2DS2-VASc score, and AF duration, were selected for analysis of independent predictors of AF recurrence. The best cut-off value of LAAV to maximize the difference in 3-year recurrence rate was estimated by plotting the standardized log-rank statistic.
Because rhythm status during LAAV measurements could be related to LAAV, sensitivity analysis was performed in patients with AF rhythm during TEE. All tests were 2-sided, and P<0.05 was considered statistically significant. Statistical analyses were performed using R 3.6.2 (R Foundation for Statistical Computing, Vienna, Austria) and SPSS Statistics 26 (IBM Corp., Armonk, NY, USA).
The mean patient age was 54.4±8.8 years and 123 (95.3%) were male. The median duration of AF was 29.1 months (IQR 9.5–57.3 months) and the median LAAV was 30.2 cm/s (IQR 23.7–41.9 cm/s). Seventy-one percent (91/129) of the patients underwent a planned electrophysiologic study as a staged procedure, including cavotricuspid isthmus ablation. Among these patients, 22 underwent additional catheter ablation using 3-dimensional mapping guidance to ablate residual potential.
There were significant differences among the low, intermediate, and high LAAV groups in the prevalence of hypertension, AF rhythm during TEE, hybrid radiofrequency catheter ablation, N-terminal pro B-type natriuretic peptide (NT-proBNP) concentrations, and echocardiographic variables, including E/e´, LA diameter, LA volume index, LA strain, and mean orifice diameter (Table 1).
Baseline Characteristics According to LAA Emptying Velocity
| Overall (n=129) |
Low LAAV (<20 cm/s; n=21) |
Intermediate LAAV (LAAV ≥20 and <40 cm/s; n=70) |
Normal LAAV (≥40 cm/s; n=38) |
P value | |
|---|---|---|---|---|---|
| Clinical | |||||
| Age (years) | 54±8.8 | 57.8±7.1 | 53.8±8.9 | 53.6±9.0 | 0.128 |
| Male sex | 123 (95.3) | 20 (95.2) | 67 (95.7) | 36 (94.7) | 0.973 |
| Body mass index (kg/m2) | 25.2±2.8 | 25.6±2.3 | 25.3±3.0 | 24.8±2.6 | 0.307 |
| Diabetes | 12 (9.3) | 3 (14.3) | 5 (7.1) | 4 (10.5) | 0.585 |
| Hypertension | 49 (38.0) | 12 (57.1) | 30 (42.9) | 7 (18.4) | 0.006 |
| Congestive heart failure | 9 (7.0) | 1 (4.8) | 5 (7.1) | 3 (7.9) | 0.900 |
| Stroke history | 19 (14.7) | 5 (23.8) | 6 (8.6) | 8 (21.1) | 0.095 |
| CHA2DS2-VASc score | 1.0 [1.0–2.0] | 1.0 [1.0–2.0] | 1.0 [0.0–1.0] | 0.0 [0.0–2.0] | 0.064 |
| RFCA history | 20 (15.5) | 1 (4.8) | 10 (14.3) | 9 (23.7) | 0.144 |
| Hybrid (staged) RFCA | 91 (70.5) | 17 (81) | 55 (78.6) | 19 (50.0) | 0.004 |
| AF duration (months) | 29.1 [9.5–57.3] | 17.6 [9.5–59.7] | 33.8 [9.0–74.2] | 30.7 [11.0–55.5] | 0.688 |
| NT-proBNP (pg/mL) | 259.7 [151.1–460.7] | 460.7 [313.5–679.4] | 280.7 [202.2–489.5] | 119.8 [53.4–204.8] | <0.001 |
| LAA fibrosis extent (%) | 38.5 [33.0–44.7] | 37.4 [34.6–43.9] | 39.9 [35.0–47.4] | 34.6 [31.1–41.9] | 0.152 |
| Echocardiography and CT | |||||
| AF rhythm during TEE | 102 (79.1) | 19 (90.5) | 61 (87.1) | 22 (57.9) | 0.001 |
| LVEF (%) | 60.0 [56.0–64.0] | 58.0 [56.0–63.0] | 59.0 [55.0–63.0] | 62.0 [56.0–65.0] | 0.226 |
| E/e′ | 8.1 [6.2–10.1] | 9.7 [7.7–11.8] | 8.1 [6.2–10.0] | 7.5 [6.0–9.5] | 0.042 |
| LA diameter (mm ) | 45.0 [40.0–50.0] | 48.4±7.2 | 45.4±6.0 | 42.9±7.0 | 0.002 |
| LA volume index (mL/m2) | 45.6 [36.4–54.8] | 52.5 [44.6–64.7] | 47.0 [36.9–55.0] | 40.0 [34.0–48.9] | 0.002 |
| LA strain (%) | 15.2 [12.1–19.2] | 13.8 [10.1–16.2] | 14.6 [11.2–18.4] | 18.9 [14.3–22.2] | 0.002 |
| Mean orifice diameter (mm) | 15.8±3.9 | 19.4±4.1 | 15.8±3.3 | 13.8±3.7 | <0.001 |
| LAA depth (mm) | 33.4±5.8 | 34.3±7.2 | 33.3±5.3 | 33.1±5.9 | 0.469 |
| LAA morphology | 0.310 | ||||
| Windsock | 39 (30.2) | 6 (28.6) | 22 (31.4) | 11 (28.9) | |
| Chicken wing | 38 (29.5) | 3 (14.3) | 21 (30.0) | 14 (36.8) | |
| Cactus | 29 (22.5) | 6 (28.6) | 18 (25.7) | 5 (13.2) | |
| Cauliflower | 23 (17.8) | 6 (28.6) | 9 (12.9) | 8 (21.1) | |
Unless indicated otherwise, values are presented as the mean±SD, median [interquartile range], or n (%). AF, atrial fibrillation; CT, computed tomography; LA, left atrium; LAA, left atrial appendage; LAAV, left atrial appendage emptying velocity; LVEF, left ventricular ejection fraction; NT-proBNP, N-terminal pro B-type natriuretic peptide; RFCA, radiofrequency catheter ablation; TEE, transesophageal echocardiography.
After the procedure, antiarrhythmic drugs were used in 125 (96.9%) patients for a median duration of 221 days (IQR 167–402 days). Amiodarone was used in 117 patients, whereas flecainide, propafenone, dronedarone, and sotalol were used in 4, 2, 1, and 1 patients, respectively. Oral anticoagulants were used in 127 (98.4%) patients for a median duration of 175 days (IQR 102–242 days).
LAA Emptying Velocity and 3-Year AF/AFL RecurrenceDuring the 3 years of follow-up, the median number of 24-h Holter monitoring episodes per patient was 4, and Holter monitoring was performed in 108 patients (83.7%). Of the 129 patients in total, 43 experienced recurrent arrhythmias, including 19 with paroxysmal AF, 17 with chronic AF, and 7 with AFL. The overall rate of event-free survival at 3 years was 65.3%. There was a significant difference in the event-free survival rate among patients with low, intermediate, and normal LAAV (Figure 2). Patients with low LAAV had a significantly lower rate of the event-free survival than those with normal (adjusted [a] HR 6.11; 95% CI 1.42–26.15; P=0.015) and intermediate (aHR 2.74; 95% CI 1.29–5.83; P=0.009) LAAV.
Freedom from atrial fibrillation (AF) recurrence according to the left atrial appendage emptying velocity (LAAV). There was a significant difference in the freedom from AF (or atrial flutter) recurrence according to the LAAV strata.
As a continuous variable, a higher LAAV was significantly associated with a lower risk of 3-year AF/AFL recurrence (per 1-cm/s increase, aHR 0.95; 95% CI 0.91–0.99; P=0.016; Table 2), with an area under the receiver operating characteristic curve of 0.76 (0.67–0.84, Supplementary Figure 1). The best cut-off value of LAAV for 3-year AF/AFL recurrence was 21 cm/s, which is similar to the cut-off point used to define low LAAV in the present study (Supplementary Figure 2). Patients with LAAV <21 cm/s had a significantly lower event-free survival than those with LAAV ≥21 cm/s (25.0% vs. 75.0%; aHR 3.34; 95% CI 1.56–7.14; P=0.002; Figure 3).
Multivariable Analysis for 3-Year AF Recurrence
| Variable | Univariable analysis | Multivariable analysis | ||
|---|---|---|---|---|
| HR (95% CI) | P value | HR (95% CI) | P value | |
| Clinical | ||||
| Age | 1.01 (0.98–1.05) | 0.575 | 3.32 (0.68–16.24) | 0.139 |
| CHA2DS2-VASc score, +1 | 1.11 (0.84–1.41) | 0.390 | ||
| Hybrid RFCA | 1.35 (0.67–2.75) | 0.401 | ||
| AF rhythm during TEE | 6.78 (1.64–28.03) | 0.008 | ||
| AF duration, +1 month | 1.00 (1.00–1.01) | 0.177 | ||
| NT-proBNP | 1.00 (1.00–1.00) | 0.404 | ||
| Echocardiographic | ||||
| E/e′ | 1.01 (0.96–1.06) | 0.790 | ||
| LA volume index, +1 | 1.03 (1.01–1.05) | 0.004 | 1.03 (1.00–1.06) | 0.075 |
| LA strain, +1 | 0.91 (0.85–0.97) | 0.003 | 0.96 (0.88–1.05) | 0.407 |
| Mean orifice diameter, +1 | 1.10 (1.02–1.19) | 0.011 | 1.04 (0.94–1.15) | 0.465 |
| LAA emptying velocity, +1 | 0.94 (0.91–0.97) | <0.001 | 0.95 (0.91–0.99) | 0.016 |
| LA diameter, +1 | 1.06 (1.01–1.11) | 0.013 | NA* | NA* |
*When left atrial (LA) diameter was included in the multivariable Cox regression model as an alternative to LA volume index, LA diameter was not significantly associated with the risk of 3-year AF recurrence (hazard ratio [HR] 1.03; 95% confidence interval [CI] 0.97–1.09; P=0.351). +1, per unit increase. Other abbreviations as in Table 1.
Freedom from atrial fibrillation (AF) recurrence according to the best cut-off value for left atrial appendage emptying velocity (LAAV). There was a significant difference in freedom from AF (or atrial flutter) recurrence between patients with an LAAV <21 cm/s and those with an LAAV ≥21 cm/s.
Figure 4 shows the rhythm status of ECGs at discharge and 6 months, 1 year, and the last follow-up after TTA. There were significant differences in the rate of sinus rhythm in the 12-month and last ECGs according to the preoperative LAAV. Patients with normal LAAV had consistently high rates of sinus rhythm at each time point.
Rate of sinus rhythm at each follow-up time point. Rhythm status was determined using the electrocardiogram obtained nearest to the specific time point. (A) All patients. (B) Patients stratified by left atrial appendage emptying velocity (LAAV). *P<0.05 compared with the LVVA ≤20 cm/s group.
Subgroup Analysis Excluding Patients With Sinus Rhythm During LAAV Measurements
In a subgroup analysis only including patients with AF rhythm during TEE, a higher LAAV was significantly associated with a lower risk of 3-year AF/AFL recurrence (per 1-cm/s increase, aHR 0.95; 95% CI 0.91 0.91–0.99; P=0.024; Supplementary Tables 1,2).
Patients with low LAAV had a significantly lower rate of the event-free survival than those with normal (aHR 4.79; 95% CI 1.19–19.67; P=0.030) and intermediate (aHR 2.75; 95% CI 1.26–5.97; P=0.011) LAAV.
The present study demonstrated the clinical implication of LAAV in patients undergoing TTA for AF. The main findings of the study are as follows. First, patients with LAAV <20 cm/s had a significantly lower rate of AF-free survival at 3 years than those with LAAV 20–40 cm/s and those with LAAV ≥40 cm/s. Second, LAAV was an independent predictor of 3-year AF recurrence after TTA.
The LAA is a remnant of the embryonic LA.25 The LAA has complex anatomical and physiological characteristics that are distinct from the rest of the LA.26,27 LAAV is influenced by many factors, including age, LAA contractility, LA pressure, and left ventricular systolic and diastolic function.11,28 Therefore, LAAV may be a candidate surrogate of comprehensive cardiac function in patients with AF. Previous studies reported that LAAV is a predictor of treatment response after electrical cardioversion or catheter ablation in patients with AF.13–15 However, the clinical value of LAAV has not been studied in patients undergoing thoracoscopic ablation for AF. Given that the only general and predictable factors, such as age and LA dimension, have been evaluated for outcome prediction in TTA,3 LAAV, which can be easily measured during TEE studies,11 may be a potential and feasible parameter for selecting surgical candidates.
In the present study, low LAAV, especially <20 cm/s, was associated with a high risk of AF recurrence. Previous studies have suggested that LAAV is one of the most powerful predictors of AF recurrence after rhythm control.13–15 In those studies, the LAAV cut-off value for AF recurrence was 28,15 31,14 or 40 cm/s.13 In the present study, LAAV 20–25 cm/s was the best cut-off value for predicting AF recurrence. The differences in optimal cut-off values among studies may be explained by the study populations, follow-up duration, and, in particular, the treatment modalities.
Atrial fibrosis is one of the direct parameters of structural changes in patients with AF. A postmortem study reported that atrial fibrosis is related to the presence of AF and its severity.9 However, in the present study, the extent of LAA fibrosis was not significantly different among the patients according to LAAV group. Rather, there were differences in various anatomical and functional parameters, including LA size, mean LAA orifice diameter, NT-proBNP concentrations, E/e′, and LA strain, among the LAAV strata. These findings suggest that in patients with AF, LAAV is not limited to LAA remodeling,29 but may be a surrogate of cardiac conditions related to AF severity. Although the low LAAV group had numerically lower AF duration among the 3 groups, the difference was not statistically significant. Given that the lower LAAV group had a larger LA diameter or LA volume index, the relatively shorter AF duration may be due to late diagnosis of AF from its development or by chance. Furthermore, LAAV was independently associated with AF recurrence, whereas traditional clinical and echocardiographic parameters were not. Univariate analysis in the present study revealed that LA enlargement, as assessed by diameter or volume index, was associated with the risk of AF recurrence, similar to a previous study.3 However, when adjusted for LAAV, LA enlargement was not identified as an independent predictor of AF recurrence. Therefore, in patients with AF planned for TTA, LAAV measurements would be recommended as a preoperative evaluation for outcome prediction and appropriate patient selection, in addition to an effort to detect anatomical and structural remodeling.3
In our early practice we used a hybrid procedure in which a routine postprocedural electrophysiologic study was performed after TTA to confirm the state of pulmonary vein isolation, followed by cavotricuspid isthmus ablation to prevent AFL. Additional AF ablations guided by 3-dimensional mapping were only performed in patients with significant residual pulmonary vein potential, at the discretion of electrophysiologists. Based on this approach, 84.5% (109/129) of patients in our study underwent TTA as their first ablation, whereas the corresponding rate in the literature is 47.1%.30 Meanwhile, the effectiveness of staged (hybrid) catheter ablation after TTA is a matter of debate. Our early experience did not demonstrate significant benefits of routine staged radiofrequency catheter ablation.19 Furthermore, the results of a randomized study do not support the routine use of electrophysiologic studies after TTA.31 In accordance with these prior studies, staged radiofrequency catheter ablation was not significantly associated with the risk of AF/AFL recurrence after TTA in our study. However, we observed that LAAV was significantly associated with the risk of AF/AFL recurrence, even after adjusting for hybrid radiofrequency catheter ablation. Therefore, LAAV was identified as a predictor of the risk of AF/AFL recurrence, independent of pre- or postprocedural catheter ablation.
Patients with LAAV <20 cm/s were at high risk of recurrent AF, but low LAAV itself cannot be a sole contraindication for TTA because most cases of recurrent AF after TTA in the present study were paroxysmal. For example, only 23.8% of patients with LAAV <20 cm/s showed AF or AFL on the last ECG despite a much higher recurrence rate, defined as at least one episode during follow-up. Indeed, all patients in this high-risk group had persistent AF at baseline. Conversely, LAAV ≥40 cm/s was associated with a sinus rhythm rate of 97% on the last ECG and a recurrence rate of 12% during follow-up, which can be a good indicator for selecting TTA candidates.
This study has several limitations. First, because this was a single-center study, the generalizability of the results may be limited. The optimal cut-off value of LAAV may differ according to the study population. Second, it is possible that LAAV was influenced by rhythm status during TEE. Therefore, we conducted a subgroup analysis only including patients with AF rhythm during LAAV measurements, and the results were consistent. Third, there may be a correlation between LAAV and echocardiographic variables. Multicollinearity potentially reduces the power of multivariable analysis. Nevertheless, LAAV remained a significant predictor of 3-year AF/AFL recurrence after adjustment for echocardiographic variables in this study. Fourth, the study population was heterogeneous due to the history or concomitant use of catheter ablation. According to the current guidelines,1,32 one of the indications for TTA is failed catheter ablation, making a history of radiofrequency catheter ablation relatively common among TTA patients. A meta-analysis reported that the prevalence of previous catheter ablation before TTA was 52.9%.30 In the present study, 15.5% of patients had a history of previous catheter ablation, which is not significantly higher than the prevalence reported in the literature. The high rate of the hybrid procedure in the present study was due to a practical strategy early at the Samsung Medical Center. However, most of these procedures only involved an electrophysiologic study with cavotricuspid isthmus ablation. Event after adjusting for the hybrid procedure, we found that LAAV remained significantly associated with the risk of AF recurrence. Finally, 24-h Holter monitoring was not performed systematically because this was an observational study. Our institution recommends annual Holter monitoring in all patients undergoing TTA and repeat testing in patients with palpitations. Consequently, 24-h Holter monitoring was performed in 83.7% (108/129) patients, with a median of 4 episodes per patient across the entire population. Twenty-one patients without Holter monitoring had multiple ECGs at each visit, but the possibility of hidden paroxysmal AF remained.
In patients undergoing TTA for AF, LAAV was an independent predictor of long-term AF recurrence. In particular, LAAV <20 cm/s was significantly associated with an increased risk of recurrent AF.
None.
The authors have no conflicts of interest to disclose relevant to the submitted work.
J.K., S.-J.P., and D.S.J. designed the study; S.C., D.K., E.K.K., S.-A.C., J.-O.C., S.-C.L., and S.W.P. obtained data. J.K., M.B., S.-J.P., and D.S.J. wrote the manuscript. All authors have read and approved the final version submitted.
This study was approved by the Institutional Review Board of Samsung Medical Center (2020-05-146-003).
Please find supplementary file(s);
https://doi.org/10.1253/circj.CJ-23-0040
