VT ablation based on CT imaging substrate visualization: results from a large cohort of ischemic and non-ischemic cardiomyopathy patients

INTRODUCTION

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.

METHODS

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

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).

CONCLUSION

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.

Long term outcome after ablation of persistent atrial fibrillation in patients with postprocedurally unmasked sinus node disease

Funding Acknowledgements

Type of funding sources: None.

Background

About three percent of patients with persistent atrial fibrillation [AF] additionally suffer from a concealed sinus node disease [SND]. We sought to determine the ablation success one year after ablation of persistent AF in patients with postprocedurally unmasked SND.

Methods and Results

In total 2239 patients with an ablation of persistent AF at our center were screened for a postprocedurally unmasked SND, which made cardiac pacing necessary within one week after ablation. In a propensity score matched case control study, the longterm ablation success of 51 patients (mean age 73±8years, 58% male) with postprocedurally unmasked SND after ablation of persistent AF was compared to that of 102 patients without SND after ablation of persistent AF. Controls were matched to cases based on the propensity score considering age, body mass index, left ventricular ejection fraction, gender, blood pressure, diabetes mellitus, atrial low voltage, previous number of ablations and method of ablation.

One year after ablation of persistent AF, 20 (39%) patients with postprocedurally unmasked SND and 61 (60%) patients without postprocedurally unmasked SND were in sinus rhythm (p=0.025). The number of repeat ablation procedures within the follow up year did not differ significantly between cases and controls (0.60±0.68 vs 0.53±0.80, p=0.574).

Conclusion

In patients with a postprocedurally unmasked SND after ablation of persistent AF, longterm ablation success seems to be worse compared to patients without postprocedurally unmasked SND.

Correlation of local impedance, global impedance and contact force with resulting lesion size in RF ablation

Funding Acknowledgements

Type of funding sources: None.

Background

During clinical application of RF-energy, several parameters are constantly observed, e.g. RF time, power, global impedance and temperature. The new parameter "local impedance" is gaining importance and might be a possible real-time marker for predicting long-lasting RF-lesions and increasing safety. The aim of this study was to investigate the correlation between local and global impedance as well as RF power and contact force.

Methods

RF-lesions were created using an ex vivo model with porcine cardiac preparations. These were put in a saline-filled container with a dispersive electrode. Global impedance was held at 120 Ohm by adjusting saline and water. Additionally, a heated thermostat and a circulation pump were installed to imitate blood flow. RF-lesions were produced with different settings of energy and contact force (20, 30, 40 and 50 watts; contact force of 0-5g, 10-15g and 20-25g). While creating the lesions, global and local impedance, temperature, energy and RF time were documented, as well as the current lesion width and depth. Local and global impedance drops were calculated as the difference between baseline impedance and current impedance.

Results

In total, 1223 measurements were made during application of RF-energy. 6 steam pops occurred. Contact force, local and global impedance changes showed highly significant correlations with lesion depth and diameter. Amongst analyzed values, local impedance drop showed highest correlation with lesion diameter and depth (r = 0,391 and 0,613; p&lt;0,001). Visualized in Figure 1 and 2, global and local impedance correlate with lesion diameter and depth.

Discussion

Local impedance was found to be a suitable real-time marker for lesion size, showing significantly higher correlations with RF lesion size than contact force and global impedance. Further investigation is necessary to find a cut off for a safe but long-lasting RF-lesion.

Safety and efficacy of transvenous lead extraction using mechanical (non-laser) extraction tools

Funding Acknowledgements

Type of funding sources: None.

Introduction

The rate of transvenous lead extraction (TLE) is increasing with an increasing rate of complex devices being implanted. TLE is now a routine part of cardiac device management and up to date data on the safety and efficacy of TLE with modern tools and techniques is essential to management decisions regarding non-infectious indications for lead extraction.

Purpose

To evaluate the safety and efficacy of TLE in a contemporary cohort using mechanical (non-laser) extraction tools.

Methods

We present a contemporary, prospective review of TLE at our high-volume cardiac centre. All patients undergoing TLE from June 2016 and June 2019 were enrolled in our local database and baseline clinical data, procedural information and outcome data were collected.

Results

In total 561 leads were explanted (n=153) or extracted (n=408) from 341 patients over the study period. Patients were predominantly male (71%) with a mean age of 65 ± 17 years. The most common indication for lead removal was lead failure (45.2%, n=154) followed by infection of the pocket or device (29.3%, n=100). The mean dwell time of the 408 extracted leads was 7.2 years; 35% had a dwell time of 5-10 years, 23% had a dwell time &gt;10 years and 4% had a dwell time &gt;20 years (Figure 1). In total, complete success was achieved in 96.4% (n=541) leads, clinical success in a further 2.1% (n=12) and failure only in 1.4% (n=8). Clinical success was high (93%) even in leads with dwell time &gt;20 years (Figure 2). There was an overall complication rate of 0.9% (3/341) for major complications and 1.5% (5/341) for minor complications. There were no deaths.

Conclusions

Our data would suggest that there are ongoing improvements in the safety profile and success rates of lead extraction undertaken by experienced operators now with a major complication rate of &lt;1%.

Electrode tissue coupling is a new main determinant of RF lesion creation, experience from a cardiac animal model

Funding Acknowledgements

Type of funding sources: None.

Background

Radiofrequency (RF) current is a classic ablation technology used in the EP lab. By now it is assumed that RF lesion size is mainly determined by RF power, duration and contact force. This ex vivo animal model study shows that a new parameter - "electrode tissue coupling" (ETC) - plays an additional major role in RF lesion creation. The ETC level describes the amount of electric contact between the RF electrode and cardiac tissue: In minor ETC levels, only the distal electrode connects to tissue. In full ETC levels, the whole RF electrode is embedded in cardiac tissue.

Methods

RF-lesions were created using 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-lesions were created using identic values of RF duration and contact force. A RF power of 20W, 30W, 40W, and 50W was used. The ETC levels were systematically varied between minor and full coupling. 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.

Results

In total, 1923 measurements during application of RF-current were analyzed. In ETC III (full tissue coupling), lesions became significantly wider and deeper. In 20W ablations, lesion diameters were significantly (1.68 fold) larger when applying ETC III instead of ETC I. This relation was found in variations of RF parameters (Table 1).

Interestingly, baseline local impedance and local impedance drop showed a high correlation with selected ETC levels. The average baseline local impedance in ETC I was 207.2 Ohm, compared to 267.3 Ohm in ETC III (p &lt; 0.01).

Discussion

In addition to by now known parameters (power, duration, contact force), electrode tissue coupling is a main determinant of lesion size. Higher ETC levels result in higher amounts of RF current going into adjacent tissue instead of current dissipation into the blood pool. In clinical practice, the ETC level can be predicted by baseline local and global impedance. Observation of these parameters should become clinical practice during RF ablation.

Procalcitonin as a biomarker of cardiac implantable electronic device pocket infection: a prospective validation study

Funding Acknowledgements

Type of funding sources: None.

Introduction

The implantation of cardiac implantable electronic devices (CIEDs) such as pacemakers and implantable cardioverter-defibrillators is increasing along with the complexitly of these devices. CIED infection is an uncommon, but severe complication associated with the presence of a device and is associated with a high mortality and morbidity. Lead-related infections and frank endocarditis are associated with a systemic inflammatory response and, in general, are readily identified. Isolated pocket infections do not produce such a systemic response and are thus more complex to diagnose. There is a reliance on clinical accumen and examination of local signs of infection. There is thus a need for a reliable biomaker to help identify cases of pocket infection.

Aim

Our group have previously shown procalcitonin (PCT) to be a potentially useful biomaker in the clinial situation of possible pocket infection. We aim to prospectively validate the proposed cut-off value of 0.05ng/ml for the procalcitonin (PCT) biomaker in an independent cohort, which we have previously identified as showing promise in this clinical situation.

Methods

In this prospective case-control validation study the PCT levels of 81 patients with confirmed pocket infections were compared to 81 controls, matched for age and renal function, presenting for elective generator replacement or lead revision unrelated to infection. Exclusion criteria included: concomitant infectious or inflammatory diseases, end-stage renal failure, active malignancy or receiving immunosuppressive therapy.

Results

A PCT over 0.05 ng/ml was found in 68% (n= 55) of pocket infections and 24% (n= 19) of controls. Using the pre­defined cut-off value of 0.05 ng/ml PCT had a sensitivity of 68% and a specificity of 77% for diagnosing pocket infections. ROC analysis revealed area under the curve of 0.752 (standard error 0.039, p &lt;0.001 ) for PCT. In patients presenting with minimal infective signs the sensivity remained high (67% vs 70% with extensive inflammation) and similarly remained high in thus who had received anti-biotic therapy prior to PCT sampling (65% vs 69%).

Conclusion

PCT is a potentially useful biomarker to aid the diagnosis of a pocket infection when used with the prospecitvely validated cut-off value of 0.05ng/ml. The sensitivity of the PCT positive result remained high even in patients pre-treated with antibiotics or with minimal clinical signs of inflammation.

Initial experience using a novel algorithm to calculate omnipolar electrograms using a high-density grid-style catheter

Funding Acknowledgements

Type of funding sources: None.

Background/Introduction

A novel mapping algorithm recently became available in Europe and select countries in the Asia Pacific region. EnSite Omnipolar Technology (OT) utilizes the Advisor HD Grid Mapping Catheter, Sensor Enabled (HD Grid) to calculate electrograms in 360 degrees from two bipolar and three unipolar electrograms acquired from a triangular set of three electrodes. This software also enables calculation of wavefront characteristics including maximum voltage, activation direction and wave speed. Procedural characteristics and clinical utilization of this novel software have not yet been reported.

Purpose

To examine the clinical utility and procedural characteristics associated with the use of this novel mapping algorithm among participating centers.

Methods

Acute procedural data were prospectively collected in 386 cases at 52 centers utilizing the newly approved mapping software in the initial phases of commercialization in Europe and the Asia Pacific region. Procedural characteristics recorded included indication for mapping/ablation, navigation mode, mapping reference, and maps and tools used to diagnose/locate ablation targets.

Results

A total of 14 indications for mapping and ablation were represented including AF, atypical flutter, and VT (Table 1). VoXel (magnetic primary) navigation mode was used in most cases (n=325, 84%). The CS catheter was used as the map reference in 280 cases (73%). A variety of workflows were used with OT to diagnose and locate ablation targets including voltage maps (n=275, 71%), LAT maps (n=226, 59%), OT activation vectors (n=124, 32%), propagation maps (n=94, 24%), and sparkle maps (n=69, 18%); note: total exceeds 100%, multiple workflows per case observed. EnSite LiveView Dynamic Display (LiveView) was used in 129 cases (33%) to diagnose and locate ablation targets, including 28 (22%) where OT activation vectors were used with LiveView. Several benefits of OT were reported including rapid identification of ablation target(s) (n=133, 35%), higher point density (n=82, 21%), better signals (n=69, 18%), and improved procedure efficiency (n=48, 12%).

Conclusion(s)

Initial experience with this novel mapping software in Europe and the Asia-Pacific region illustrated utility in a variety of arrhythmias to diagnose and locate ablation targets. The use of OT provided several benefits including rapid identification of ablation targets and higher point density, however further examination of its impact on procedural efficiencies and acute outcomes is likely warranted.

Safety of high power and short duration ablation (70 watts over 5–7 seconds) in patients with persistent atrial fibrillation undergoing pulmonary vein isolation and additional substrate modification

Background

In paroxysmal atrial fibrillation (AF), pulmonary vein isolation using HPSD has shown a promising success rate compared to ablation using conventional power settings, as well as a significant reduction in procedural and ablation time. In persistent atrial fibrillation, left atrial substrate modification seems to be a promising additional ablation approach besides pulmonary vein isolation (PVI). However, results after additional substrate ablation are not consistently positive, which may be related to non-transmural lesions and tissue oedema. An extended time of the procedure may also influence safety. Recent publications showed that HPSD ablation provides more sufficient lesions due to acute cell necrosis instead of cell oedema.

Purpose

The aim of this study is to evaluate the safety of HPSD ablation in patients undergoing ablation of persistent atrial fibrillation with PVI and additional substrate modification.

Methods

We studied and compared n=300 patients from our register undergoing the first ablation of persistent atrial fibrillation with HPSD settings (n=150) between May 2018 and January 2019 and standard settings (n=150) between July 2017 and January 2018. Patients were followed up for three months to report procedure-related adverse events. In all patients, a modified stepwise approach using PVI followed by electrogram-guided substrate modification and linear-ablation, if necessary, was performed. A HPSD ablation was performed with 70 watts with a maximum duration of 5–7 seconds. Catheter irrigation was set to 20 ml/min using the Flexability™ ablation catheter and the Ampere™ generator. The patients were compared with a historical cohort that underwent PVI using a conventional power protocol with 30–40 watts over 20–40 seconds, using the same ablation catheter. A transthoracic echocardiogram was performed in all patients after the ablation-procedure and on the following day. Duplex sonography or clinical control were performed to assess groin complications.

Results

Baseline characteristics and procedural data are shown in table 1. No significant difference in the complication rates in both groups was observed by a significant procedure-time reduction in HPSD-Group (2:13h vs 2:31h p&lt;0,001) and overall low risk of the procedure. No deaths, thromboembolic complications or atrioesophageal fistula were registered. Complication rates with statistical relevancy are shown in table 2.

Conclusion

Complex ablation using PVI and additional substrate modification in persistent atrial fibrillation using HPSD seems to be equally as safe regarding procedure-related outcomes as standard power settings ablation and can significantly reduce the time of the overall procedure.

Funding Acknowledgement

Type of funding sources: None.

European early experience with a novel 3D mapping system

Funding Acknowledgements

Type of funding sources: None.

Introduction

Catheter navigation and 3-dimensional (3D) cardiac mapping are critical for successful electrophysiological ablation procedures. A novel 3D mapping system received CE Mark in July 2020. The system offers two imaging modalities: magnetic-based (VoXel) and impedance-based (NavX). Real-time display of 3D location and catheter movements is achieved via a magnetic field frame and magnetic sensors with supplemental impedance data when operating in VoXel mode or primarily via an impedance field generated from surface electrodes in NavX mode. To address limitations in data collection commonly experienced during 3D mapping, a new respiratory compensation algorithm, patient movement detection module, and metal compensation algorithm have been developed to enable consistent data collection throughout the full respiratory cycle even in challenging cases and lab environments.

Purpose

To examine the clinical utility and procedural characteristics associated with the use of this novel 3D mapping system among participating centers.

Methods

Procedural data was collected in cases utilizing the newly cleared mapping system during the initial evaluation phase in Europe. Procedural characteristics recorded included indication for mapping and ablation, rhythm mapped, chambers mapped, and procedure time.

Results

Procedural data was collected from over 250 cases across 12 European centers. A total of 12 indications for mapping and ablation were represented including de novo and redo atrial fibrillation (paroxysmal, persistent, long-standing persistent), ventricular tachycardia (ischemic, non-ischemic) or premature ventricular contraction, and supraventricular arrhythmias (typical and atypical atrial flutter, atrioventricular nodal reentrant tachycardia, atrioventricular reentrant tachycardia). Over 70% of the cases were performed in VoXel mode. Impedance mode was mostly used in SVT cases or when the case was intended to be completed with minimal fluoroscopy. The most commonly mapped rhythms were sinus rhythm during voltage mapping and atrial tachycardia. The majority of cases (over 65%) were completed under conscious sedation; general anesthesia was used in 20% of the cases (15% not reported). The respiratory compensation algorithm was utilized in over 90% of the cases. For cases in which pre-procedural computed tomography or magnetic resonance imaging were available, operators indicated that the model shape was accurate when compared to pre-procedural imaging in 96% of the cases performed in VoXel mode.

Conclusions

Initial European experience with this novel 3D mapping system included a wide variety of arrhythmias in the atria and ventricles. This new mapping system offered operators the flexibility to tailor to specific procedure needs with two imaging modalities which were both widely utilized.

Repeat ablation for paroxysmal atrial fibrillation - Does adenosine play a role in predicting pulmonary vein reconnection patterns?

BACKGROUND

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

Catheter Ablation for "Lone" Atrial Fibrillation: Efficacy and Predictors of Recurrence

BACKGROUND

Atrial fibrillation in otherwise healthy young patients has been termed "lone" atrial fibrillation (AF). The best treatment choice is still under discussion. The aim of this study was to report on efficacy and safety of catheter ablation.

METHODS

Among 855 patients referred to our center between 2011 and 2013, 76 (9%) met the diagnostic criteria for lone AF (mean age 45 ± 8 years; mean LA diameter 37 ± 4 mm; paroxysmal AF 82%; persistent AF 18%). The primary endpoint was freedom from any atrial tachycardia after the first ablation; the secondary endpoint was freedom from any atrial tachycardia after the last ablation procedure without antiarrhythmic drugs.

RESULTS

The primary endpoint occurred in 56 patients (74%) after a mean follow-up time of 444 ± 344 days. The secondary endpoint occurred in 73 patients (96%) after a mean of 1.3 ablations/patient during a follow-up time of 459 ± 366 days. The risk of AF recurrence was not influenced by AF duration or by the type of AF (paroxysmal versus persistent). In a multivariate regression analysis smoking (P = 0.001), first degree atrioventricular block (P = 0.001), and early (< 3 months) AF recurrence (P = 0.001) were independently associated with a higher risk of AF recurrence. Major peri-procedural adverse events did not occur.

CONCLUSIONS

Catheter ablation in young healthy patients is highly effective and safe. The outcomes are maintained during long-term follow-up irrespective of preoperative AF duration. Patients with AF recurrence were more likely to smoke, have first degree AV block and early AF recurrence.