Abstract
Background:
Atrial fibrillation (AF) results in electrical and structural remodeling of the atria, which extent is known to be associated with a higher AF recurrence rate after catheter ablation (CA). Recently, a novel echocardiographic parameter derived from tissue Doppler imaging (TDI) [PA-TDI] has been introduced to assess the total atrial activation time, as a noninvasive surrogate of fibrosis and remodeling. The aim of the study is to investigate the role of PA-TDI interval as a predictor of AF ablation efficacy.
Methods:
We retrospectively included patients with paroxysmal symptomatic drug-refractory AF referred to our institution for CA procedure, who presented sinus rhythm at admission. A complete transthoracic echocardiogram was performed before the ablation procedure, including the assessment of PA-TDI interval.
Results:
From January 2015 to April 2018, 128 patients (mean age: 61.86 ± 9.08 years, 68% male, body surface area: 1.97 ± 0.21 mq, body mass index: 26.98 ± 3.86 kg/mq, and ejection fraction: 59% ±6.06%) with symptomatic drug-refractory AF who received radiofrequency CA were enrolled. During the follow-up of 15.80 ± 6.7 months, 30 patients (23%) developed AF recurrence out of the blanking period. Compared with those without recurrence (group 1), patients with recurrence (group 2) had a larger left atrium (LA) size (Group 1 vs. Group 2: mean LA area: 22.2 ± 4.6 cmq vs. 25 ± 6.6 cmq, P = 0.015; mean indexed LA volume: 35 ± 10 mL/mq vs. 40 ± 12 mL/mq, P = 0.04) and longer PA-TDI interval (Group 1 vs. Group 2: 162 ± 33 ms vs. 133 ± 26 ms, P < 0.0001). A cutoff of PA-TDI > 150 ms identified patients with recurrence after ablation with a sensibility of 82% and specificity of 83% (area under the curve 0.879).
Conclusions:
The total activation time assessed by PA-TDI is an independent predictor of AF recurrence and can be used to predict the efficacy of transcatheter ablation.
Keywords: Atrial fibrillation, left atrium, PA-TDI, tissue Doppler imaging, transcatheter ablation
INTRODUCTION
Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia with a projected prevalence of 14–17 million patients affected by the year 2030 in the European Union.[1] AF remains one of the major causes of stroke, heart failure, sudden death, and cardiovascular morbidity. With the large increase in AF burden expected in the coming decades, a better diagnosis, risk stratification, and treatment selection are pivotal. Catheter ablation (CA) has become a common treatment for patients with symptomatic, drug-resistant AF[1,2] considering the acceptably low-risk procedure related. The success rate of CA, defined as no AF recurrence after 3 3-month blanking period, is around 70% for patients with paroxysmal AF and 50% in those with persistent AF, according to large prospective registries.[1] Multiple factors have already been identified as predictors of AF recurrence after CA, such as age, AF duration, ventricular and atrial function, and comorbidities; nevertheless, their predictive value is rather small.[1,2,3] Therefore, new predictors of procedural outcome are needed for a better identification of the most suitable candidates for ablation procedure.
It is well known that AF can result in electrical and mechanical changes in the left atrium (LA) and lead to extended remodeling, which is characterized by atrial enlargement, decreased atrial voltage, and prolonged inter- and intra-atrial conduction time. Electrical and structural changes in the atrium have been found to be associated with a higher AF recurrence rate after CA or electrical cardioversion. Currently, the most commonly used method to estimate the extent of atrial remodeling is the measurement of LA size, which is also an independent predictor of new-onset AF in the general population.[3,4]
In daily clinical practice, it is common experience that even patients with small atria could relapse; therefore, cardiac magnetic resonance (CMR) imaging has gained a central role in establishing the burden of atrial fibrosis.[5]
All these observations suggest the need for a better characterization of the remodeling process beyond cardiac size to improve ablation results.
Recently, total atrial conduction time (TACT) has been proposed as a marker of atrial remodeling, and a novel echocardiographic parameter based on tissue Doppler imaging (TDI) has been introduced to assess it.[6] Preliminary studies demonstrated that a long PA-TDI interval is associated with a low LA voltage and long LA activation time and could influence AF ablation efficacy outcome.[6,7,8] However, these studies were conducted retrospectively and included small size populations; moreover, significant technological advances in ablation technique have also occurred over the last decade, with a consequent improvement in long-term success rates that should be the object of investigation.
The study aimed to investigate the role of PA-TDI in predicting AF recurrences in patients with paroxysmal AF after CA procedure.
METHODS
Patient population
Between January 2015 and April 2018, patients with symptomatic drug refractory paroxysmal AF with an indication to receive CA according to European Society of Cardiology guidelines, referred to our Institution, were enrolled.
Exclusion criteria were: AF or atrial flutter at hospital admission, pregnancy, age <18 years, moderate-to-severe valvular heart disease (including mechanical aortic or mitral valve prosthesis), congenital heart disease, acute coronary syndrome, or revascularization in the previous 6 months.
Written informed consent was obtained for the use of collected data for research purposes according to the actual privacy policy.
Echocardiographic examination
All patients underwent a comprehensive transthoracic echocardiographic examination the day before the ablation procedure, performed according to the standards of the American Society of Echocardiography (ASE),[24] and records were analyzed by an experienced echocardiographer.
Two-dimensional (2D) transthoracic echocardiography was performed using a commercially available ultrasound system (iE33; Philips, Andover, MA, USA) and an X5-1 phased array transducer with the patient in the left lateral decubitus. Before each acquisition, images were optimized for endocardial visualization by modifying the gain, compress, and gain compensation controls. 2D and color Doppler data were obtained in the parasternal short- and long-axis views and the apical two- and four-chamber views. All images were electrocardiogram (ECG)-triggered and stored in cine loop format for offline analyses.
Image acquisition included:
Conventional parameters in the apical 2- and 4-chamber views: left ventricular (LV) dimensions (LVEDd, LVESd, and LV volumes), left ventricular ejection fraction (LVEF), LV filling pattern (peak E, peak A, E/A ratio, and mitral deceleration time), and LA dimensions (area, diameter, and volume)
TDI: pulsed wave Doppler (PW) at mitral annulus (4-chamber view)
PA-TDI: obtained by calculating the time duration difference between the onset of the echocardiogram-derived P-wave and the peak of the A’ wave on lateral mitral annulus TDI. An example of PA-TDI assessment is shown in Figure 1.
Figure 1.
Example of measurement of PA-TDI duration with color-coded tissue Doppler imaging image. A fixed pixel region of interest was placed on the left atrium lateral wall just above the mitral annulus, deriving a velocity curve of the segment. The PA-TDI duration is assessed by measuring the time interval between the onset of the P-wave of the surface ECG and the peak A’-wave on the tissue Doppler tracing. 2D = Two-dimensional, TDI = Tissue Doppler imaging, PW = Pulsed-wave Doppler
Ablation procedure
All patients underwent radiofrequency (RF) CA procedures according to our institution standards. In all cases, transseptal approach was used to reach and map the left atrium. All patients received intravenous heparin to maintain an activated clotting time of 300–400 s. A nonfluoroscopic electro-anatomical mapping system was employed to guide the ablation procedure using both the Carto3 (Biosense Webster Inc., Diamond Bar, CA, USA) and the Ensite Velocity/Precision (St. Jude/Abbott Medical, Sylmar, CA, USA) mapping system. Irrigated ablation catheters with contact force technology (ThermoCool Smart-Touch, Biosense Webster Inc., or TactiCath, Abbott) were used to isolate pulmonary veins (PVs) (wide antral encircling ablation). RF current was applied at 30–35 W with a maximum temperature of 45°C and an irrigation flow of 17 mL/min until a bipolar voltage of <0.1 mV was achieved, with a maximum of 60 s per point. The endpoint of the procedure was PV isolation as confirmed by recording entrance block during sinus rhythm (SR) or pacing from the coronary sinus and exit-block showing loss of atrial capture during pacing from PVs. Some additional linear or focal RF applications were necessary in a few patient groups with evidence of low and fragmented atrial signals at the voltage map.
Follow-up
After the ablation, patients were followed up at 3, 6, and 12 months, and subsequent follow-up visits were scheduled annually thereafter, according to the practice of the center. Electrocardiogram (ECG) recordings were acquired on each visit, and 24-h Holter registrations were scheduled after 3, 6, and 12 months of follow-up. For those patients who did not attend the planned in-hospital follow-up visit, a telephone interview was performed. Importantly, all patients were encouraged to immediately obtain an ECG registration when experiencing palpitations. All medications were continued for at least 3 months. Afterward, antiarrhythmic drugs were discontinued at the discretion of the physician. After the blanking period of 3 months, recurrence of AF was defined as any recording of AF on ECG or an episode longer than 30 s on 24-h Holter registration.
Data statistical analysis
All variables have been tested for a normal distribution using the Kolmogorov–Smirnov test. Data were presented as the mean value and standard deviation for normally distributed continuous variables, median with 25–75th interquartile range for not Gaussian distributed continuous variables, and proportions for categorical variables.
The association between the PA-TDI interval and other parameters (including but not limited to LA size) has been evaluated using regression analysis. The AF recurrence-free survival curve has been plotted using the Kaplan–Meier method with the statistical significance examined by the log-rank test. Univariable and multivariable Cox regression analyses have been used to identify the factors associated with AF recurrences after ablation. Variables with a P < 0.05 in the univariate models have been included in the multivariate analysis. Receiver operator characteristics (ROC) curves have been used to identify the performance of the strongest independent predictors of AF recurrence at multivariate analysis.
RESULTS
Characteristics of the study population
Demographics
Baseline characteristics and principal echocardiographic findings are summarized in Tables 1 and 2.
Table 1:
Clinical characteristics and comparison between the two groups (Group 1: No AF recurrence during follow-up, Group 2: AF recurrence out of the blanking period)
| Clinical characteristics | Overall population (n=128) | No AF recurrence (n=98) | AF recurrence (n=30) | P |
|---|---|---|---|---|
| Age (years) | 61.8±9 | 62±9 | 61±8 | 0.877 |
| Male gender, n (%) | 88 (77) | 67 (68) | 21 (70) | 0.776 |
| BSA (m2) | 1.97±0.21 | 1.96±0.20 | 1.99±0.22 | 0.445 |
| BMI (kg/m2) | 26.9±3.8 | 26.6±3.5 | 27.9±4.6 | 0.121 |
| CAD, n (%) | 9 (7) | 7 (7.1) | 2 (6.7) | 0.928 |
| Hypertension, n (%) | 80 (62.5) | 56 (57) | 24 (80) | 0.023 |
| Diabetes, n (%) | 11 (8.59) | 6 (6) | 6 (17) | 0.071 |
| Medication, n (%) | ||||
| Class III AAD | 24 (18.75) | 16 (18) | 8 (29) | NS |
| Class IC AAD | 69 (53.9) | 56 (63) | 13 (48) | NS |
| ACEIs/ARBs | 52 (41) | 38 (43) | 14 (51) | NS |
| No drugs | 11 (8.7) | 9 (9.1) | 2 (6.6) | NS |
AF=Atrial fibrillation, CAD=Coronary artery disease, AAD=Anti-arrhythmic drug, ACEIs=Angiotensin converting enzyme inhibitors, ARBs=Angiotensin receptor blockers, BSA=Body surface area, BMI=Body mass index
Table 2:
Echocardiographic findings and comparison between the two groups
| Echo characteristics | Overall population (n=128) | No AF recurrence (n=98) | AF recurrence (n=30) | P |
|---|---|---|---|---|
| LV ejection fraction (%) | 58.9±6.1 | 59.6±4.8 | 56.8±8.6 | 0.031 |
| LA diameter (mm) | 41.2±6.3 | 40.8±6.2 | 42.4±6.5 | 0.253 |
| LA area (cm2) | 22.9±5.3 | 22.2±4.6 | 25.0±6.6 | 0.015 |
| iLA volume (mL/m2) | 36.6±11.1 | 35.5±10.3 | 40.3±12.6 | 0.047 |
| Peak E wave velocity (cm/s) | 72.8±15.8 | 72.9±14.9 | 72.8±18.7 | 0.982 |
| Peak A velocity (cm/s) | 70.2±17.6 | 70.0±18.4 | 70.9±15.1 | 0.866 |
| E/A ratio | 1.8±0.33 | 1.09±0.33 | 1.02±0.34 | 0.501 |
| E/e’ ratio | 6.8±2 | 6.8±1.9 | 6.7±2.3 | 0.872 |
| PA-TDI time | 140.5±30.8 | 132.66±26.06 | 162.22±33.08 | <0.001 |
AF=Atrial fibrillation, LV=Left ventricle, LA=Left atrium, TDI=Tissue Doppler imaging, iLA=indexed left atium
We evaluated 128 patients (88 males [68%], 63 ± 9 years) with symptomatic drug refractory paroxysmal AF who underwent RF CA in our institution. All patients were in SR when received transthoracic echocardiography. The entire patients’ population was divided into two groups: after a mean follow-up of 15.80 ± 6.7 months, 98 patients (77%, Group 1) maintained stable SR and 30 patients (23%, Group 2) experienced a recurrence of AF. The mean time to AF recurrence was 12 ± 6 months.
No relevant difference in demographic features was observed between groups, except for a slightly higher incidence of hypertension in patients with an arrhythmic recurrence (Group 1 vs. Group 2: 24 (80%) vs. 56 (57%), P = 0.023). Conversely, there were no significant differences in terms of mean age, sex, body surface area, body mass index, and incidence of comorbidities such as diabetes and ischemic heart disease [Table 1].
The procedural endpoint of PVs isolation was reached in all patients and no major procedural complications occurred.
Echocardiographic findings
According to ASE normal values cutoffs,[24] we observed that the overall study population had normal mean LV ejection fraction (EF) (58.96% ±6.6%), dilated LA (mean LA diameter: 41.2 ± 6.30 mm, LA area: 22.9 ± 5.30 cm2, and indexed LA volume: 36.65 ± 11.07 mL/m2) and normal average LV diastolic function (PW E wave: 72.87 ± 15.86 cm/s, PW A wave: 70.25 ± 17.58 cm/s, E/A ratio: 1.07 ± 0.33, and E/e’ ratio = 6.78 ± 2.01).
Comparing the two groups, Group 2 presented a significantly more dilated LA, in terms of area (Group 1 vs. Group 2: 22.2 ± 4.60 cm2 vs. 25 ± 6.6 cm2, P = 0.015), indexed left atium (iLA) volume (Group 1 vs. Group 2: 35 ± 10 mL/m2 vs. 40 ± 12 mL/m2, P = 0.04) but not in LA diameter (Group 1 vs. Group 2: 40.8 ± 6.2 mm vs. 42.2 ± 6.5 mm, P = 0.253), and slightly impairment of LV EF (Group 1 vs. Group 2: 60% ± 5% vs. 59% ± 8%, P = 0.03). There were no significant differences between groups in terms of diastolic function. More in detail: PW Doppler E wave velocity (Group 1 vs. Group 2: 72.9 ± 14.9 cm/s vs. 72.8 ± 18.7 cm/s, P = 0.982), A wave velocity (Group 1 vs. Group 2: 70.0 ± 18.4 cm/s vs. 70.9 ± 15.1 cm/s, P = 0.866), E/A ratio (Group 1 vs. Group 2: 1.09 ± 0.33, Group 2 = 1.02 ± 0.34, P = 0.501), and E/e’ ratio (Group 1 vs. Group 2: 6.8 ± 1.9, Group 2 = 6.7 ± 2.3, P = 0.872) were similar [Table 2].
The mean PA-TDI interval of the overall population was 140.49 ± 30.84 ms. Patients with AF recurrence during follow-up (Group 2) had a significantly longer PA-TDI duration at baseline in comparison to patients who maintained sinus rhytm (SR) [Group 1 vs. Group 2: 133 ± 26 ms vs. 162 ± 33 ms, P < 0.0001 – Figure 2].
Figure 2.
Box plots showing the mean difference in PA-TDI interval time duration between patients with atrial fibrillation recurrence and patients in sinus rhythm during follow-up. TDI = Tissue Doppler imaging, AF = Atrial fibrillation, SR = Sinus rhythm
Univariate and multivariate Cox proportional hazard analysis was performed to identify clinical and echocardiographic predictors of AF recurrence after CA. As shown in Table 3, hypertension, LVEF, LA area, iLA volume, and PA-TDI were identified as predictors at univariate analysis, but only PA-TDI and LA area result as an independent predictor of recurrence of AF at multivariate analysis (in the model of multivariate regression analysis, we considered only the covariates associated to a P < 0.05 on univariate analysis).
Table 3:
Univariate and multivariate proportional hazard cox analysis of AF recurrence predictors
| Univariate analysis |
Multivariate analysis |
|||||
|---|---|---|---|---|---|---|
| HR | 95% CI | P | HR | 95% CI | P | |
| Male gender | 0.98 | 0.45–2.10 | 0.957 | - | - | - |
| Age | 0.99 | 0.95–1.03 | 0.649 | - | - | - |
| Hypertension | 2.36 | 1.96–5.79 | 0.041 | 1.57 | 0.55–4.50 | 0.393 |
| CAD | 0.59 | 0.14–2.53 | 0.486 | - | - | - |
| Diabetes | 1.90 | 0.72–4.98 | 0.189 | - | - | - |
| E/e’ ratio | 0.98 | 0.76–1.24 | 0.858 | - | - | - |
| BSA | 1.98 | 0.40–10.70 | 0.383 | - | - | - |
| BMI | 1.05 | 0.96–1.15 | 0.220 | - | - | - |
| LV ejection fraction | 0.93 | 0.86–0.98 | 0.010 | 1.05 | 0.95–1.15 | 0.277 |
| LA diameter | 1.04 | 0.97–1.12 | 0.212 | - | - | - |
| LA area | 1.01 | 1.03–1.16 | 0.003 | 1.13 | 1.01–1.27 | 0.048 |
| LA indexed volume | 1.03 | 1.01–1.07 | 0.019 | 0.98 | 0.92–1.04 | 0.582 |
| PA time | 1.01 | 1.01–1.02 | <0.001 | 1.01 | 1.03–1.06 | 0.022 |
LV=Left ventricle, LA=Left atrium, CAD=Coronary artery disease, BSA=Body surface area, BMI=Body mass index, CI=Confidence interval, HR=Hazard ratio, PA time interval from ECG P wave to Doppler A wave
To investigate the discriminative performance of PA-TDI duration and LA area to predict AF recurrence, ROC analysis was performed. The area under the ROC curve for LA area is 0.6126 (95% confidence interval [CI] = 0.479–0.718, P = 0.032) indicating a low discriminative power. The area under the ROC curve for PA-TDI interval was 0.879 (95% CI = 0.798–0.928, P < 0.0001), demonstrating a good degree of discrimination [Figure 3]. Considering a cutoff point of 150 ms, a sensitivity of 82% and a specificity of 83% were obtained; Kaplan–Meier analysis showed an elevated AF recurrence probability for those patients with a PA-TDI interval longer than 150 ms [Figure 4].
Figure 3.
Receiver operator characteristic curve analyses of the total atrial conduction time (PA-TDI duration) and left atrial area according to the recurrence of atrial fibrillation during follow-up, showing higher area under the curve, thus higher discriminative power of PA-TDI when compared to left atrial area. TDI = Tissue Doppler imaging. LA = Left atrium, ROC = Receiver operator characteristics
Figure 4.
Kaplan–Meier curve for freedom of atrial fibrillation, dividing the population into two groups based on a cutoff of PA-TDI duration of 150 ms, excluding a 90-day blanking period. Curves show significant differences between groups based on PTA-DI higher or lower than 150 ms (P < 0.01) TDI = Tissue Doppler imaging
DISCUSSION
In the last years, the scientific community has demonstrated a huge effort trying to identify reliable parameters which could be related to a higher risk of suffering an arrhythmic recurrence after a CA procedure. A large number of parameters as age, arterial hypertension, type of AF, LA size, and impaired LV systolic function have been proposed and investigated.[4,5,6,7,8,9] Interestingly, all these parameters seem to either cause or reflect the presence and extent of atrial remodeling.[9] Transthoracic echocardiographic measurement of LA size has been largely accepted as one of the major predictors of maintenance of SR,[10] and its being easily obtained has made it particularly appealing in the clinical practice. However, conflicting data on the relationship between mild or moderate LA enlargement with prognosis and the long-term maintenance of SR have been published.[11] Moreover, manually traced 2D echocardiographic LA areas are often limited by poor temporal and spatial resolution.[12]
Increased LA volume is a morphological expression of chronic diastolic dysfunction[13] and a measure of cardiovascular risk burden.[14] Increased LA size has been shown to be highly predictive of AF occurrence and stroke in the general population and indexed LA volume was independently associated with Framingham cardiovascular risk score, congestive heart failure, vascular disease, TIA, and stroke.[14] In our study population, LA area and iLA volume are significantly higher in those patients who suffered AF recurrence in the univariate analysis; nevertheless, only LA area was confirmed as an independent predictor of maintenance of SR after CA in the multivariate analysis, although its discrimination power is low.
Diastolic function, evaluated by transmitral PW Doppler parameters, and more specifically E wave velocity, A wave velocity,[15] and E/e’ ratio, was already demonstrated to be associated with a higher risk of AF recurrence.[16] On the other hand, Di Salvo et al. described the role of atrial myocardial deformation properties in predicting the maintenance of SR after external cardioversion.[27] According to the current literature data, in our study, the multivariate analysis demonstrated that none of the above is notwithstanding an independent predictor of AF recurrence.[16]
In addition to atrial enlargement, a decelerated atrial conduction velocity might be another consequence of atrial remodeling.[17] Indeed, atrial dilatation and the reduction of the atrial conduction velocity can result in a larger number of re-entrant wavelets inside the atria, as suggested by Gaspo et al.[17] in dog models. This condition could favor the development and perpetuation of AF.[18]
TACT is the time elapsed between the initiation of atrial depolarization (usually in the region of the sinus node) and the last depolarization (usually in the lateral LA wall) of the same activation front. TACT prolongs in case of increased atrial size or decreased conduction velocity. Therefore, theoretically, a prolonged TACT should correlate with vulnerability for AF. Several techniques have been examined to quantify TACT: signal-averaged electrocardiogram signal-average electrocardiogram (SAE) P-wave duration is a well-established noninvasive method to estimate TACT and has been reported that a longer P-wave duration on SAE is an independent predictor of new-onset AF as already suggested by Guidera and Steinberg[25] and Hayashida et al.[26]
Recently, cardiac magnetic resonance imaging (MRI) was introduced to establish the burden of atrial fibrosis, and there are strong evidences that such fibrosis could be a major determinant in the AF ablation efficacy outcome.
The efficacy of delay enhancement MRI-guided ablation in comparison to a conventional CA procedure was the main issue of investigation of the DECAAF study.[5] In this large multicenter observational study, patients were referred to receive CA after late gadolinium enhancement (LGE)-CMR and the procedure was CMR guided. Arrhythmia recurrence was observed to be related to the extent of global atrial fibrosis and was an independent predictor in the covariates analysis.[5] However, due to the well-known practical limitations, both late-gadolinium MRI and signal-averaged-ECG P-wave duration are not largely used in clinical routine. Besides the leading research of Oakes et al. based on LGE cardiac MRI to reflect LA arrhythmic substrate,[19] it has been shown that TACT measured noninvasively using echocardiography (PA-TDI interval) correlates with the degree of structural atrial remodeling.[7]
The PA-TDI interval is an easily achievable, fast, low-cost, and reliable method to estimate the TACT. This novel echocardiographic parameter has been already validated against P-wave duration on signal-averaged electrocardiography.[6] Several studies have largely evaluated this tool, confirming its reliability and diagnostic accuracy, both in patients undergoing AF RF CA[20] and in patients undergoing electrical cardioversion (CV).[21] In particular, we extended the evaluation of the predictive value of the PA-TDI interval to a midterm follow-up. Other authors have shown how the parameter is a good predictor of early recurrence of AF. Indeed, den Uijl et al. reported that a prolonged value (146 ± 20 ms according to their results) was associated with AF recurrence after CA.[20] Our analysis shows that patients with PA-TDI duration longer than 150 ms have a significant higher probability of arrhythmic recurrence, as well shown in the Kaplan–Meier curves [Figure 4]. Similarly, also Fukushima et al. found out that PA-TDI was an independent predictor of AF recurrence in patients with paroxysmal AF[23] and they reported the same cutoff of 150 ms. In these studies, patients were treated without modern contact force technology which has been demonstrated to allow better outcomes.[22] In our study, TACT still maintains his significant predictive value and his role could become pivotal in the contact force ablation era for patient selection.
LA size is merely an expression of structural changes, caused by atrial remodeling. Conversely, TACT reflects both structural (since it is directly proportional to LA dimensions) and electrical changes (expressed by atrial conduction velocity) and provides a more comprehensive estimation of the amount of global atrial remodeling.
The main clinical implication of our results is that the routine use of PA-TDI could help the physician to get a better selection of those patients who could benefit the most from a CA procedure. The early identification of patients with a higher chance to maintain SR after CA could influence the therapeutic choice (rhythm or frequency control strategies, management of antiarrhythmic drugs, and anticoagulants) and that could drive to a possible remarkable economic impact on the public health system. On the other hand, those patients who are supposed to have an extremely low possibility of freedom from AF could be saved to be exposed to a procedural risk.
Limitations
The main limitations of the study are the relatively small population and the absence of a control group.
Although patients received a 24-h Holter monitoring at 3, 6, and 12 months and an ECG in the presence of symptoms, we are aware that a considerable number of AF episodes could remain asymptomatic. This is an important methodological limitation of the study. Another study limitation is the use of two different electro-anatomical mapping systems for PV isolation that could have an impact on the outcome of some patients, even if has not been investigated so far.
CONCLUSIONS
The PA-TDI interval can reflect the process of atrial remodeling, such as LA enlargement, and when applied in clinical practice could be a convenient parameter for predicting a recurrence after CA of AF.
Ethical statement
The study was conducted according to the declaration of Helsinki. All patients signed written informed consent for the procedure and for the use of collected data for research purpose.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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