Background
Time has been postulated as an important factor for electrical remodeling of the left atrium (LA) in persistent atrial fibrillation (AF) (‘AF begets AF’). However, it is still a matter of ...debate if structural changes are the cause or consequence of AF. We sought to determine the clinical and invasive parameters, which correlate with LA scar as determined by voltage mapping, in patients with persistent AF.
Methods
Seventy consecutive patients undergoing ablation of persistent (49%) or long-standing persistent AF (51%), between January 2013 and February 2014, were enrolled in the study. Besides clinical parameters, 2D echocardiographic assessment of LA size and LA pressure (LAP) after transseptal puncture was also considered. Bipolar endocardial signals with a mean voltage amplitude < 0.1 mV during AF were defined as LA scar.
Results
In the univariable analysis, LA scar was associated with age, gender, coronary artery disease (CAD), glomerular filtration rate (GFR), LA size and LAP. Arrhythmia duration, mild to moderate mitral regurgitation (MR), left ventricular dysfunction and left ventricular hypertrophy showed no significant correlation with atrial scar (all
p
> 0.05).
In a multivariable regression model, LA scar area was independently associated with age, female gender and LA area. AF duration was not associated with LA scar.
Conclusions
In this study, older age, greater LA area and female gender predicted the degree of LA scar, while other variables tested did not. In particular, we found no significant association between AF duration and LA scar.
The eradication of ventricular tachycardia (VT) isthmus sites constitutes the minimal procedural endpoint for VT ablation procedures. Contemporary high-resolution computed tomography (CT) imaging, in ...combination with computer-assisted analysis and segmentation of CT data, facilitates targeted elimination of VT isthmi. In this context, inHEART offers digitally rendered three-dimensional (3D) cardiac models which allow preoperative planning for VT ablations in ischemic and non-ischemic cardiomyopathies. To date, almost no data have been collected to compare the outcomes of VT ablations utilizing inHEART with those of traditional ablation approaches.
The presented data are derived from a retrospective analysis of n = 108 patients, with one cohort undergoing VT ablation aided by late-enhancement CT and subsequent analysis and segmentation by inHEART, while the other cohort received ablation through conventional methods like substrate mapping and activation mapping. The ablations were executed utilizing a 3D mapping system (Carto3), with the mapping generated via the CARTO® PENTARAY™ NAV catheter and subsequently merged with the inHEART model, if available.
Results showed more successful outcome of ablations for the inHEART group with lower VT recurrence (27% vs. 42%, p < 0.06). Subsequent analyses revealed that patients with ischemic cardiomyopathies appeared to derive a significant benefit from inHEART-assisted VT ablation procedures, with a higher rate of successful ablation (p = 0.05).
Our findings indicate that inHEART-guided ablation is associated with reduced VT recurrence compared to conventional procedures. This suggests that employing advanced imaging and computational modeling in VT ablation may be valuable for VT recurrences.
Background
High-power short-duration (HPSD) radiofrequency ablation (RFA) is highly efficient and safe while reducing procedure and RF time in pulmonary vein isolation (PVI). The QDot™ catheter is a ...novel contact force ablation catheter that allows automated flow and power adjustments depending on the local tissue temperature to maintain a target temperature during 90 W/4 s lesions. We analysed intraprocedural data and periprocedural safety using the QDot-catheter in patients undergoing PVI for paroxysmal atrial fibrillation (PAF).
Methods
We included
n
= 48 patients undergoing PVI with the QDot-catheter with a temperature-controlled HPSD ablation mode with 90 W/4 s (TC-HPSD). If focal reconnection occurred besides repeat ablation, the ablation mode was changed to 50 W/15 s (QMode).
N
= 23 patients underwent cerebral MRI to detect silent cerebral lesions.
Results
Mean RF time was 8.1 ± 2.8 min, and procedure duration was 84.5 ± 30 min. The overall maximal measured catheter tip temperature was 52.0 °C ± 4.6 °C, mean overall applied current was 871 mA ± 44 mA and overall applied energy was 316 J ± 47 J. The mean local impedance drop was 12.1 ± 2.4 Ohms. During adenosine challenge,
n
= 14 (29%) patients showed dormant conduction. A total of
n
= 24 steam pops were detected in
n
= 18 patients (39.1%), while no pericardial tamponade occurred. No periprocedural thromboembolic complications occurred, while
n
= 4 patients (17.4%) showed silent cerebral lesion.
Conclusions
TC-HPSD ablation with 90 W/4 s using the QDot-catheter led to a reduction of procedure and RF time, while no major complications occurred. Despite optimized temperature control and power adjustment, steam pops occurred in a rather high number of patients, while none of them leads to tamponade or to clinical or neurological deficits.
Pulmonary vein (PV) reconduction after PV isolation (PVI) unmasked by adenosine is associated with a higher risk for paroxysmal atrial fibrillation (PAF) recurrence. It is unknown if the reconnected ...PVs after adenosine testing and immediate re-ablation can predict reconnection and reconnection patterns of PVs at repeat procedures. We assessed reconnection of PVs with and without dormant-conduction (DC) during the first and the repeat procedure.
We included 67 patients undergoing PVI for PAF and a second procedure for PAF recurrence. DC during adenosine administration at first procedure was seen in 31 patients (46%). 264 PVs were tested with adenosine; DC was found in 48 PVs (18%) and re-ablated during first procedure. During the second procedure, all PVs where checked for reconnection.
Fifty-eight patients (87%) showed PV reconnection during the second procedure. Reconnection was found in 152/264 PVs (58%). Of 216 PVs without reconnection during adenosine testing at the first ablation, 116 PVs (53.7%) showed reconnection at the repeat procedure. Overall, 14.9% of patients showed the same PV reconnection pattern in the first and second procedure, expected statistical probability of encountering the same reconnection pattern was only 6.6%(p = 0.012).
In repeat procedures PVs showed significantly more often the same reconnection pattern as during first procedure than statistically expected. More than 50% of initial isolated PVs without reconnection during adenosine testing showed a reconnection during repeat ablation. Techniques to detect susceptibility for PV re-connection like prolonged waiting-period should be applied. Elimination of DC should be expanded from segmental to circumferential re-isolation or vaster RF application.
Abstract
Funding Acknowledgements
Type of funding sources: None.
Background
It has been shown recently that ablation of paroxysmal and persistent atrial fibrillation (AF) using very high-power-short ...duration (vHPSD) ablation protocol is safe and effective. Data for vHPSD ablation protocol in adult patients with congenital heart disease (ACHD) are lacking. We searched our database for ACHD patients undergoing AF ablation using vHPSD ablation regarding periprocedural safety and outcome.
Methods
The data of 62 consecutive ACHD patients with mild (n=43; 69.4%), moderate (n=15; 24.2%) or complex (n= 4; 6.4%) CHD were analysed (Table 1 ). Mean age was 60,43 ± 12,7 years ( 46% male) with a Cha2ds2-VASc2 Score median of 2. Patients were diagnosed with paroxysmal AF (n= 24; 38%) or persistent AF (n= 38; 61%). In 6 patients (9,6 %), a previous conventional pulmonary vein isolation (PVI) had been performed.
Settings used for vHPSD ablation were 70 W/5-7 s or 60 W/7-10 s using irrigated-tip catheters. Circumferential PVI was performed in all 62 patients; in 30 patients (48%) additional substrate ablation was performed. The 30-day incidence of adverse events was analyzed and patients followed-up in regular visits at our outpatient clinic using repetitive 7 days Holter ECGs every 3 months.
Results
No adverse events such as cardiac tamponade, pericardial effusion >10mm, transient ischemic attack/stroke, atrio-esophageal fistula, cardiac arrest or death occurred. Vascular access complications were detected in 7/62 patients (11%), including 4 patients with a need of intervention (surgical n=2, thrombin injection n=2).
Complete PVI was performed in all patients (mean procedure time 129 ± 42min, mean fluoroscopy time 9,09 ± 5.44 min. Radiofrequency (RF) time was 127.27 ± 7,25 min (111,43 ± 27,83 min PVI only, 148,76 ± 46,07 min PVI + substrate ablation).
After a mean follow up of 249 days, freedom of any atrial arrhythmia off antiarrhythmic drugs (AAD) after a single ablation procedure was present in 26/47 patients (55.3%). Success rate was significantly higher in patients with paroxysmal AF (n=16/18; 88%) compared to patients with persistent AF (n=10/29; 34.5%; p< 0.001; Figure 1) Conclusion: In this first study using vHPSD in ACHD patients of variable complexity with paroxysmal or persistent AF, the technique was safe and effective. Major periprocedural complications were rare and limited to vascular access problems. No vHPSD ablation modality-related complications occurred. vHPSD was fast in all patintes regardless of CHD complexity. Results in the paroxysmal CHD group were excellent and encouraging for persistent AF.
Abstract
Funding Acknowledgements
Type of funding sources: None.
Background
Radiofrequency current remains one of the most important techniques for catheter ablation. Creating durable lesions is key ...for sufficient and safe procedures. Several possibilities were tested for estimating the progress of lesion formation. For instance, force-time-integral, ablation index and lesion size index are used to assess quality of RF-application and, therefore, lesion size and durability. Nevertheless, recovered conduction after acute conduction block remains an issue in RF-ablation. The aim of this study was to evaluate local impedance (LI) changes as real time surrogate for lesion formation.
Methods
RF-lesions were created using an ex vivo porcine cardiac model and a force and local impedance sensing catheter. The experimental setup consisted of a saline-filled container, a dispersive electrode, a heated thermostat and a circulation pump to imitate in vivo conditions. Global impedance was kept at 120 Ohm as well as the temperature at 37°C. RF-lesions were created using identic values of RF duration and contact force. RF power (20W, 30W, 40W, 50W) and level of electrode-tissue-coupling were also systematically varied between minor and full coupling. In minor ETC-level, only the distal end of the catheter is in contact with the tissue. In full ETC-level, the whole catheter tip is in contact with the tissue.
All parameters (power, temperature, global and local impedance, contact force, ETC, lesion size) were measured constantly during application of RF-current, enabling real-time correlation of RF parameters and lesion size. In case of an audible steam pop, RF application was stopped.
Results
Including a total of 8654 measurements into the analysis, maximum diameter and depth were 9.51 ± 1.91 mm and 7.29 ± 2.50 mm in average. Local impedance correlated well with lesion depth (r= 0,78, p<0,001), as well as lesion diameter (r=0,652, p<0,001, Figure 1).
After significant declines of LI at the beginning of RF-application, it slowly approximates a minimum. Lesion size on the other hand, rises exponentially in first seconds and gets closer to a maximum after more than 25 seconds. This relationship is illustrated in Figure 2. With decreasing lesion growth at the end of RF-application, LI changes decrease to low level (Figure 3).
Conclusion
Lesion formation in RF-ablation is not linear during application of RF current. Local impedance changes seem to be a suitable real-time surrogate for assessing changes in lesion size during ablation.
Abstract
Funding Acknowledgements
Type of funding sources: None.
Background
Several parameters are assumed to influence lesion size in RF ablation. Especially RF power, duration and contact force are ...considered for optimizing lesion quality and creating durable lesions. Recent data showed a significant influence of electrode-tissue-coupling (ETC) on lesion size and occurrence of steam pops. Therefore, this study aimed to investigate the impact of ETC and contact force on lesion progression in RF ablation.
Methods
RF-lesions were created using a contact force sensing catheter with the ability of measuring local impredance in an ex vivo porcine cardiac model. The experimental setup consisted of a saline-filled container, a dispersive electrode, a heated thermostat and a circulation pump to imitate in vivo conditions. Global impedance was kept at 120 Ohm as well as the temperature at 37°C. RF power of 20W, 30W, 40W, and 50W was used. The ETC levels (full/minor) and CF-level (1-5g, 10-15g and 20-25g) were systematically varied between minor and full coupling. In minor ETC-level, only the distal end of the catheter is in contact with the tissue. In full ETC-level, the whole catheter tip is in contact with the tissue. All parameters (power, temperature, global and local impedance, contact force, ETC, lesion size) were measured constantly during application of RF-current, enabling real-time correlation of RF parameters and lesion size. In case of an audible steam pop, RF application was stopped.
Results
8654 measurements out of 72 lesions were included in analysis. Significant differences in lesion size were observed when ETC-level was differed. Lesion depth was significantly higher in full ETC-level (5.13 ± 0.99 mm vs. 9.45 ± 1.45 mm, p<0.001). No significant difference was seen in lesion diameter and depth by varying CF-level, when lesions were created in full ETC-level (Table 1). These findings are also illustrated in Figure 1.
When lesions were analyzed in minor ETC-level only, significant differences were observed, when CF-levels were varied (Table 2).
Conclusion
ETC is a main predictor of lesion size in RF-ablation. CF also influences lesion depth and diameter. However, significant differences were only observed in minor ETC-levels. Consequently, CF might be a main factor for durable lesions in RF-ablation, but the influence of varied CF decreases when ETC-level is rising.
Abstract
Funding Acknowledgements
Type of funding sources: None.
Background
Radiofrequency ablation remains one of the most important ablation techniques in the EP lab. Creating durable lesion is ...difficult, as progression of lesion formation cannot be observed directly. Surrogate parameters, as force-time-integral and indices, as the ablation index or lesion size index, help distinguishing the efficacy of a RF-application, but several deficiencies are known. The aim of this study was to further investigate dynamic changes in ablation parameters and lesion growth in RF-ablation.
Methods
RF-lesions were created using an ex vivo porcine cardiac model with a force and local impedance sensing catheter. A second catheter was used for lesions up to 70 Watts. The experimental setup consisted of a saline-filled container, a dispersive electrode, a heated thermostat and a circulation pump to imitate in vivo conditions. Global impedance was kept at 120 Ohm as well as the temperature at 37°C. RF-lesions were created using identic values of RF duration and electrode tissue coupling. RF power of 20W, 30W, 40W, and 50W was used in the local impedance sensing catheter, while RF power of 30W, 40W, 50W, 60W, and 70W were used in the second catheter.
All parameters (power, temperature, global impedance, ETC, lesion diameter and lesion depth) were measured once per second during application of RF-current, enabling real-time correlation of RF parameters and lesion size. In case of an audible steam pop, RF application was stopped.
Results
In total, 61 lesions were included in the analysis. Due to at least 60 measurements per lesion, 3321 data points with all ablation parameters (power, temperature, global impedance, lesion diameter and lesion depth) were collected and analyzed.
Throughout the application, lesion progression was highest in the first seconds of RF application and showed a slowing approximation to a maximum (Figure 1 and 2). Potential maximum lesion size seems to be defined by selected power level (s. Figure 3). Interestingly, these findings were seen in all power levels from 20 – 70 W (s. Figure 3).
75 % of final lesion size was achieved after 12-25 seconds, depending on selected power levels (s. Figure 4). In high power ablation (> 50 W), 75% of final lesion size was reached significantly earlier compared to lower power levels (20-40 W, s. Figure 4).
Conclusion
In RF-ablation, lesion growth is not linear. A slowing approximation of lesion diameter and depth to a maximum is observed. This finding should be considered in clinical settings to avoid steam pops and collateral damage due to a long RF duration despite little changes in lesion size. Further investigation is needed for a surrogate parameter, which is able to assess declining lesion growth after the first seconds of RF-application.
Abstract
Funding Acknowledgements
Type of funding sources: None.
Background
Radiofrequency current remains one of the most important ablation techniques in the EP lab. Creating durable lesions is key ...to successful ablation. Evaluating lesion quality and progression of lesion growth is difficult as many parameters influence lesion formation. Therefore, several approaches were developed, as monitoring RF duration, power and contact force seems insufficient in clinical practice. Force-time-integral (FTI) and force-time-current-integral (FTCI), as well as the ablation index (AI) and lesion size index (LSI) showed decent results in past studies. Recently, a new force sensing catheter (NFSC) was released. By now, data about lesion formation and correlation with the FTI, FTCI and LSI is lacking with this NFSC. This study aimed to further investigate lesion formation with the NFSC in an ex vivo model.
Methods
30 RF-lesions were created using an ex vivo porcine cardiac model with the NFSC catheter. The experimental setup consisted of a saline-filled container, a dispersive electrode, a heated thermostat and a circulation pump to imitate in vivo conditions. Global impedance was kept at 120 Ohm as well as the temperature at 37°C. In a first set of lesions, CF was varied (1g, 5g, 10g, 20g). Three lesions were created in each CF-level with 30W. In a second set of lesion, CF was kept at 10 – 15 g, but ablation power was set to 20W, 30W, 40W, 50W, 60W and 70W. In every power level, three lesions were created.
All parameters (power, temperature, global impedance, contact force, lesion size) were measured constantly during application of RF-current, enabling real-time correlation of RF parameters and lesion size. In case of an audible steam pop, RF application was stopped.
Results
1640 measurement in 30 lesions were included into the analysis. Mean lesion diameter was 7.82 ± 1.52 mm, mean lesion depth 4.80 ± 1.08 mm. Baseline global impedance (GI) was 138.10 ± 10.93 Ω, mean GI-drop 28.10 ± 8.00 Ω. In average, CF of 12.10 ± 5.87 g was used.
Correlations of lesion size, FTI and FTCI are shown in table 1. Interestingly, LSI correlated best with lesion size (r = 0.851 and r = 0.852 for lesion depth and diameter; p<0.001). Figure 1 illustrates a scatter plot of LSI and lesion depth (Figure 1a) and lesion diameter (Figure 1b).
Figure 2 shows dynamic changes in lesion depth compared to changes in LSI and FTCI. During RF-application, development of lesion formation and LSI is comparable from approximately second 7 onwards. FTCI is rising in a linear manner, whereas lesion formation increases monoexponentially.
Conclusion
In the NFSC, lesion size correlates strongest with the LSI in power levels up to 70 Watts. FTI and FTCI also showed decent correlations. Regarding dynamic changes in lesion size, LSI is best comparable to actual lesion growth.
Abstract
Funding Acknowledgements
Type of funding sources: None.
Introduction
In persistent AF, outcomes after PVI alone is worse as the pathophysiology remains unclear. Prolonged AF duration is an ...independent predictor for worse success rates after catheter ablation. In this study, we investigated efficacy and safety of ablation of spatio-temporal dispersions, as additional ablation strategy after PVI in patients with long-standing persistent AF.
Methods
All consecutive patients with long-standing persistent AF treated with an AI-based algorithm for detection of spatio-temporal dispersion in our institution between 05/21 and 10/22 were included (n = 41, see table 1). The procedure was done using a high-density 3D-Map and an algorithm for detection of right and left atrial areas with spatio-temporal dispersion (DISPERS). Ablation of DISPERS was aiming at homogenizing, dissecting, isolating or connecting DISPERS areas to non-conducting structures. Follow-up contained regular visits at our out-patient-clinic and repetitive 7 day Holter ECGs. Late recurrence (LR) was defined as recurrence after 90 days or as recurrence, which caused further ablation. All complications requiring intervention or causing long-term sequelae were classified as major complications.
Results
In 24/41 pts (58.5%), the DISPERS guided ablation was the first AF ablation. Patients were suffering from very long-standing persistent AF with a mean AF duration of 64.89 ± 54.77 months. Additional to circumferential PVI, ablation of all detected left atrial (100%) and right atrial (68.3%) DISPERS areas was performed, leading to significant slowing of AF cycle length (mean 23.3%) or termination of AF to AT (5/41, 12.2%) or direct conversion to SR (6/41, 14.6%).
One major complication occurred (1/41 (2.4%), pseudoaneurysm, resolving after manual compression). Three patients (7.3%) required temporary external pacing due to delayed sinus recovery after the procedure. No patient was in need of permanent pacemaker implantation.
LR occurred in 25 patients (61.0 %): In 8/25 patients (32 %), LR was solely AF, whereas in 15/25 patients (60%) LR was a left AFlutt. In 2 patients (8%), AF and left AFlutt was detected.
During a follow-up of 231 ± 129 days, 72.9 % of patients remained in sinus rhythm undergoing 1.6 ± 0.68 ablations (s. Figure 1; 4,9% of patients on AAD). Additionally, Figure 2 illustrates the AF-free outcome in all patients.
Conclusion
Ablation of arrhythmogenic substrate identified by spatio-temporal dispersion yielded in this cohort of extensively long-standing persistent AF patients in high success rates regarding elimination of AF. Most arrhythmia recurrences were reentrant AT. After a total of 1.6 procedures, freedom from AF and AT was >72%. Despite prolonged procedure times, complication rates remained very low. Extending study population and follow-up is needed to evaluate long-term efficacy of dispersion-guided ablation.
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