Five waves of COVID-19 pandemic in Italy: results of a national survey evaluating the impact on activities related to arrhythmias, pacing, and electrophysiology promoted by AIAC (Italian Association of Arrhythmology and Cardiac Pacing)

BACKGROUND

The subsequent waves of the COVID-19 pandemic in Italy had a major impact on cardiac care.

METHODS

A survey to evaluate the dynamic changes in arrhythmia care during the first five waves of COVID-19 in Italy (first: March-May 2020; second: October 2020-January 2021; third: February-May 2021; fourth: June-October 2021; fifth: November 2021-February 2022) was launched.

RESULTS

A total of 127 physicians from arrhythmia centers (34% of Italian centers) took part in the survey. As compared to 2019, a reduction in 40% of elective pacemaker (PM), defibrillators (ICD), and cardiac resynchronization devices (CRT) implantations, with a 70% reduction for ablations, was reported during the first wave, with a progressive and gradual return to pre-pandemic volumes, generally during the third-fourth waves, slower for ablations. For emergency procedures (PM, ICD, CRT, and ablations), recovery from the initial 10% decline occurred in most cases during the second wave, with some variability. However, acute care for atrial fibrillation, electrical cardioversions, and evaluations for syncope showed a prolonged reduction of activity. The number of patients with devices which started remote monitoring increased by 40% during the first wave, but then the adoption of remote monitoring declined.

CONCLUSIONS

The dramatic and profound derangement in arrhythmia management that characterized the first wave of the COVID-19 pandemic was followed by a progressive return to the volume of activities of the pre-pandemic periods, even if with different temporal dynamics and some heterogeneity. Remote monitoring was largely implemented during the first wave, but full implementation is needed.

Real-world survival of model-3501 subcutaneous implantable defibrillator lead

Funding Acknowledgements

Type of funding sources: None.

Background

In December 2020, the subcutaneous implantable cardioverter-defibrillator (S-ICD) lead model-3501 was subject to a safety notification because of increased risk of fracture at a location just distal to the proximal sense ring. The manufacturer’s product performance report currently reports a lead survival probability of 98.8% at 45 months. However, no multicenter long-term performance information exists for this lead.

Purpose

Our aim was to assess the longevity of model-3501 leads and to compare it with that of the previous model-3401.

Methods

This analysis included consecutive patients who received an S-ICD with a model-3501 or a model-3401 lead at 66 Italian participating centers of the Rhythm Detect registry. A lead failed if it required extraction/replacement because of abnormalities suggestive of a structural defect, e.g. out-of-range impedance, nonphysiological electrical noise or ineffective therapy.

Results

From January 2013 to July 2021, 2403 patients were implanted and followed up (78% male, age 49±15years, ejection fraction 45±16%, body mass index 26±4Kg/m2). A 3501-model lead was used in 1697 patients and a 3401-model in 706 patients. During a median follow-up of 38 months [25th–75th percentile: 24-55], we detected 4 malfunctioning model-3501 leads and 2 model-3401 leads. After analysis of the returned leads by the manufacturer’s technical services, a single model-3501 lead failure was a fracture distal to the proximal ring electrode, as described in the manufacturer’s advisory letter. No deaths or permanent injuries occurred as a result of lead failures. The survival of 3501-model leads at 4 years was 99.5% (95% confidence interval, 99.0 to 99.9) compared with 99.9% (95% confidence interval, 99.6 to 100.0) of 3401-model leads (p=0.110). The cumulative occurrence rate of the 3501-model safety notification fracture was 0.1% (95% confidence interval, 0.0 to 0.3).

Conclusions

In this large multicenter analysis, the survival probability of model-3501 S-ICD leads was in line with that reported by the manufacturer, was not significantly lower than that of 3401-model leads (not affected by a safety notification), and still higher than that reported with transvenous leads. Although an enhanced electrode is now available, which addresses the potential for electrode body fracture, the present findings are reassuring and may have significant implications for the management of patients who have affected leads.

Dielectric-based tissue thickness measured during radiofrequency ablation catheter

Funding Acknowledgements

Type of funding sources: None.

A new dielectric-based method of KODEX-EPD mapping system (EPD Solutions) for measuring tissue thickness at the catheter-tissue interface has recently been developed. We reported preliminary data on real-time catheter-based measuring myocardial wall thickness in vivo, during typical atrial flutter (AFL) RF ablation.

The Kodex version used to perform this type of analysis is a version not commercially available yet but only for case replay and research purpose, not used in clinical practice.

The study population consisted of 12 consecutive patients, suffering from symptomatic paroxysmal or persistent cavo-tricuspid isthmus (CTI) dependent. The Wall Viewer (WV) function is measured by assessing a series of dielectric signals derived directly from real-time local interrogation of the catheter-tissue interface. WV is displayed in millimeters, with either high or low confidence levels per met or unmet prerequisite acquisition criteria respectively and it is displayed as a color code scale (Fig. 1, A).

The anatomy of the CTI was identified using the 4mm MAP-iT irrigated ablation catheter. A suitable starting point for the ablation, in the proximity of the tricuspid valve, and a final location in the junction between the inferior vena cava and the right atrium, were precisely defined based on electrograms recorded. Subsequently, "point by point" CTI ablation was performed delivering RF energy with 30/40 Watts for 20-40 seconds with an interlesion distance ≤6 mm.

9 patients had paroxysmal common AFL, 3 persistent common AFL. The mean age was 64±9 years, 10 (83%) were male. The mean body mass index was 30±6, 9 (75%) patients had hypertension, and 1 (8%) had coronary artery disease. The mean procedure time was 37±13 min, the mean fluoroscopic time was 690±378 s, the mean RF time 763±205 s, with a mean number of RF pulses of 28±7. The mean cavo-tricuspid isthmus length was 29.5±2.6 mm. The atrial wall thickness was significantly higher close to the tricuspid annulus than close to the inferior vena cava (3.6±0.5 mm vs 2.4±0.3 mm, p<0.001) and a trend towards a progressive decrease of atrial wall thickness was observed moving the mapping catheter from the tricuspid valve to the inferior vena cava (Fig. 1, B). Acute bidirectional cavo-tricuspid isthmus block was achieved in all patients without any complications.

We first describe a new mapping technology that allows atrial wall thickness measurement and, as expected, the wall thickness was higher close the tricuspid annulus and lower towards the inferior vena cava. The possibility to calculate the substrate thickness before RF delivery could deeply change the way to perform RF ablation, allowing a tailored energy delivery thus increasing the efficiency of the procedures and potentially reduction of the risk of complications.

Detectable reentrant circuits in localized microreentrant tachycardias in the era of ultra high-density mapping

Funding Acknowledgements

Type of funding sources: None.

Background

Optimal criteria in clinical practice differentiating microreentrant atrial tachycardias (mAT) from macroreentrant atrial arrhythmias (MAT) have not yet been clarified. The use of multielectrode catheters and the recent development of ultra high-density mapping (UHDM) with automated features has improved our knowledge of mAT circuits and foci location.

Purpose

In the present study, we systematically evaluated AT mechanisms in a large consecutive cohort of patients with MAT identifying the precise mAT circuits using the Rhythmia mapping system.

Methods

Consecutive patients indicated for MAT ablation from January 2021 to November 2021 at 33 centers were prospectively included. All MATs were completely mapped in the left or right atrium by means of the Rhythmia mapping system and the 64-poles Orion basket catheter. For study purpose, a mAT was defined as an AT with slow continuous low fragmented potentials covering at least 50% of tachycardia cycle length (CL) in a small area (set as a circuit within < 1 cm2) and in a couple of closed splines of the Orion catheter and a centrifugal activation pattern to the remainder of the atria. The Lumipoint tool was systematically used to confirm EGM fragmentation inside this area. Data are reported as mean±SD.

Results

One-hundred eighty-seven MATs were analyzed: 100 (53.7%) atypical left atrial flutter, 27 (14.3%) left AT and 60 (32%) right AT. A total of 7 MAT (prevalence of 3.7%) was identified as mATs (6 atypical left atrial flutter and 1 AT), with 5 out 7 with a previous history of AF ablation procedure. The percentage of atrial surface with a voltage level below 0.1 mV was 19±17%. The CL was 329±78ms. The electrical activity spanning the whole CL was detected by 2±0.6 pairs of close bipoles of the Orion catheter, and was actually confined to a region of 0.4±0.2cm2 with continuous highly fractionated potential covering 68±10% of the CL (longest component of fractionated EGM per spline=74±18% of the CL). Voltage level was 0.3±0.1mV at RF delivery site and 0.2±0.1mV at the site of longest duration of the fragmented potential, respectively. Targeted mAT activity was identified closer to PVs in three cases and at the mid portion of the anterior wall and at the roof in two cases each, respectively. In all cases a single shot RF delivery terminated each arrhythmia at targeted location. Consolidative RF ablations were then delivered in the adjacent area. No complication occurred. At three months follow-up all patients remained free from any AT recurrence.

Conclusions

In this standard of care clinical experience with UHDM system, the prevalence of mAT seems to be higher than previously reported in literature. A technique based on mAT identification through a novel automated algorithm and matched area of electrogram fractionation captured by the Orion catheter may limit the extent of ablation needed.

The impact of RF wattage level on local impedance and procedural parameters in AF ablation cases

Funding Acknowledgements

Type of funding sources: None.

Background

Local impedance (LI) measurement can provide information on catheter tip contact, but also changes in LI during ablation can inform the extent and effectiveness of RF energy delivery. To date the relationship between highly LI measurements and contact force (CF) during atrial fibrillation (AF) ablation at different levels of energy delivery is still lacking.

Purpose

We aimed to evaluate the impact of power setting on LI and key procedural parameters in AF ablation cases.

Methods

A novel CF ablation catheter equipped with dedicated algorithm was used to measure LI at the distal electrode of this catheter. Radiofrequency (RF) catheter applications ≥45 watts were categorized as high power (HP) and applications <45w as standard power (SP). Ablations were also grouped according to different levels of CF (<5g, 5-14g, 15-24g and ≥25g). Data are reported as mean±SD.

Results

Sixty-two consecutive pts undergoing RF catheter ablation of AF from the CHARISMA registry were included A total of 4619 ablation spots performed around PVs were analyzed (58% paroxysmal, 84% de novo, RF deliveries per pt=76±27, RF delivery time=9.1±5s, CF=12.3±8g). The majority of these were HP applications (n=4192, 91%). The mean LI was 158±17Ω prior to ablation and 138±14Ω after ablation (p<0.0001, absolute LI drop of 21.9±8Ω) with a LI drop rate equal to 4.4±3Ω/s. HP ablations had significantly shorter RF delivery times, 8.8±4s vs 12±7s (p<0.0001), larger LI drops (22.2±8Ω vs 19.3±9Ω, p<0.0001) and higher LI drop rates (4.5±3Ω/s vs 3.6±2Ω/s, p<0.0001) than SP, respectively. For both HP and SP settings, the magnitude of LI drop increased and RF delivery time decreased with increasing amounts of CF. The largest differences between HP and SP were found when CF was <15g (RF delivery time: 9±5s at HP vs 12.9±7s at SP, percentage of difference 26.3%, p<0.0001; LI drop: 21.2±8Ω at HP vs 18.6±9Ω, percentage of difference -14.3%, p<0.0001). No major complications occurred during the procedures. All PVs were successfully isolated.

Conclusions

This preliminary experience suggests that, HP ablation is effective and safe and resulting in shorter RF delivery times and larger LI drops than SP ablation.

Influence of catheter orientation on local impedance parameters during radiofrequency delivery in AF ablation

Funding Acknowledgements

Type of funding sources: None.

Background

Recently, a novel contact force (CF) sensing catheter able to measure local tissue impedance (LI) providing a measure of tissue characteristics has become available for clinical use.

Purpose

We sought to evaluate the influence of catheter contact angle on LI and CF parameters in consecutive atrial fibrillation ablation cases.

Methods

Consecutive pts undergoing radiofrequency catheter (RFC) ablation of AF from the CHARISMA registry were included. A novel ablation catheter (IntellaNav Stablepoint catheter) with dedicated algorithm (DirectSense) was used to measure LI at the distal electrode of this catheter. Each targeted spot was characterized in terms of RF delivery time, catheter contact angle, baseline LI and subsequent LI drop during ablation at different levels of CF (<5g, 5-19g and ≥20g). RFC ablations were performed at ≥45 watts. Data are reported as mean±SD.

Results

A total of 4193 point ablations performed around PVs from 54 cases of AF ablation were analyzed (57% paroxysmal, 85% de novo). The LI was 157±17Ω prior to ablation and 137±14Ω after ablation (p<0.0001, absolute LI drop of 22±8Ω). The CF was 12.5±8g and the RFC delivery time was 8.8±4s. The LI drop increased as CF increased (ranging from 18.9±7Ω for CF<5g to 24.8±7Ω for CF≥20g, p<0.0001) as well as RFC delivery time decreased (ranging from 12.7±4s for CF<5g to 6.6±4s for CF≥20g, p<0.0001). The LI drop at perpendicular orientations was significantly lower than at parallel orientations (19.5±8Ω vs 23.4±8Ω, p<0.0001) and RFC delivery time was higher (9.6±5s vs 8.4±4s, p<0.0001). This trend was confirmed among different level of CF both for LI drop and RFC delivery time. Figure

Conclusions

In this experience, the magnitude of the LI drop at perpendicular orientation were significantly lower than at parallel orientation and RFC delivery time was greater in parallel instances than in perpendicular instances. Thus, perpendicular RF ablations required longer RF applications and produced weaker LI decreases that parallel lesions, suggesting that catheter orientation may have critical role in RF delivery for ablation.

Ventricular tachycardia channels ablation incorporating automated high-density mapping guidance: data from the CHARISMA registry

Funding Acknowledgements

Type of funding sources: None.

Background

Ventricular tachycardia (VT) ablation targeting conducting channels (CC)s based on timing of late potentials (LPs) during sinus rhythm (dechanneling) may facilitate a scar homogenization strategy without the need for extensive ablation and possibly lead to higher successful rate.

Purpose

We evaluated the feasibility and safety of a CC identification and ablation approach by means of an ultra-high density mapping system with a novel automated algorithm in ischemic VT procedures.

Methods

Consecutive patients indicated for ischemic VT ablation were prospectively included. A complete map of the left ventricle was performed prior and after ablation through the Rhythmia mapping system. Channels were defined as any signal activity bounded by anatomic and functional barriers and characterized through the Lumipoint (LM) tool and continuous activation was used on the whole ventricular substrate. Procedural end point was the elimination of all identified CCs by ablation at the CC entrance and exit followed by abolition of any residual LPs inside the CC. The ablation endpoint was noninducibility. Data are reported as mean±SD.

Results

A total of 36 channels were identified through LM from 28 patients (1.2±0.5 per patient): 21 (75%) patients had 1 CC, 6 (21.4%) had 2 CCs and 1 (3.6%) had 3 CCs. LPs were identified inside CCs in 19 cases (67.9%). In 8 cases (28.6%) LPs were present both inside and outside and in 1 (3.6%) case LPs were present only outside the CC. LPs inside channels covered an area of 7.6±5 mm2 with a ratio between LPs area and CCs’ area of 67.4±31.8%. In 12 (43%) cases LPs area covered more than 90% of the CCs’ area. At voltage map analysis a total of 34 CC were identified: 1 CC was present in 75% of the cases, 2 CCs in 17.9% and 3 CCs in 3.6%. LPs were identified only inside CCs in 46.4% of the cases, both inside and outside in 42.9% and only outside in 10.7%. Healthy tissue (voltage level≥0.5mV) was prevalent (68.2±17%), followed by intermediate voltage areas (0.5-0.05 mV; 31.1±17%) and very low voltage areas (<0.05mV; 0.7±1%). LPs were found mostly at intermediate voltage areas (57.0±34% of the covered area; 39.1±33% at healthy tissue and 3.4±13% at very low voltage areas). LM was more accurate than traditional voltage mapping in identifying CCs: in 6 (21.4%) cases voltage map overestimated LPs areas, in 2 (7.1%) cases failed to fully identify LPs and only in 19 out 28 (67.8%) LM and voltage map had a complete agreement. All CCs’ entrance and exit were successfully ablated and abolition of any residual LPs inside the CC was achieved in all patients. No complication occurred. Noninducibility was achieved in all (100%) the cases.

Conclusions

In this experience, a channel identification approach through the advanced Lumipoint tool was more accurate than traditional voltage mapping and seems to be safe, feasible, and effective at least in the acute setting of ischemic VT ablation.

A novel local impedance algorithm to guide effective pulmonary vein isolation in AF patients: preliminary experience among different voltages of atrial substrate

Funding Acknowledgements

Type of funding sources: None.

Background

Recently, a novel technology able to measure local tissue impedance (LI) and contact force (CF) aimed at validating ablation endpoints has become available for clinical use.

Purpose

This analysis explores the relationship between LI parameters, substrate characteristics and AF type during ablation in AF patients.

Methods

A novel ablation catheter with dedicated algorithm was used to measure LI at the distal electrode. Each ablation point was characterized in terms of RF delivery time, baseline LI and LI drop during ablation according to different voltages (above or below 0.5 mV) of the atrial substrate. Ablation endpoint was PVI as assessed by entrance and exit block with local capture. Data are reported as mean±SD.

Results

A total of 2032 RFC deliveries from 34 consecutive patients were analyzed (71% paroxysmal AF, 29% persistent AF). All PVs were successfully isolated with an overall procedure time of 128±33min (fluoroscopy time=15.6±9min, RF delivery time=9.6±4s, CF=11.1±7g). The baseline LI was 155±17Ω prior to ablation and 136±14Ω after ablation (p<0.0001, absolute LI drop of 21.0±8Ω) with a LI drop rate equal to 2.8±2Ω/s. Ablation spots were more frequently deployed in high-voltage areas (>0.5mv, n=1240, 61%). Baseline LI and LI drops were both higher when underlying atrial voltages were >0.5mV than when <0.5mV (156±18Ω vs 153.6±16Ω for starting LI, p=0.0032; 22.2±8Ω vs 19.1±8Ω for LI drop, p<0.0001, respectively). No differences were found in terms of both CF and LI after ablation between >0.5mV and <0.5mV (11.0±7g vs 11.2±7g for CF, p=0.3435; 136.4±13Ω vs 135.3±15Ω for ablated tissue LI, p=0.1521, respectively). Low-voltage areas were more frequently detected at ablated spots in persistent AF cases (n=288, 51.9%) than in paroxysmal AF cases (n=504, 35.1%, p<0.0001), however, no differences were found in terms of both baseline LI and LI drop between persistent and paroxysmal AF cases (156.3±17Ω vs 154.6±17Ω for starting LI, p=0.135; 20.7±8Ω vs 21.1±9Ω for LI drop, p=0.1722, respectively).

Conclusions

LI measurements well distinguished contact with high-voltage areas from low-voltage areas and were able to detect significant differences in LI drop during ablation according to the voltage level.

Feasibility and efficacy using the KODEX-EPD imaging system in right atrial flutter ablation: a single center experience

Background

Isthmus-dependent right atrial flutter is the most frequently encountered atrial flutter in clinical practice (80–90% of atrial flutters).

Purpose

The aim of our study was to assess as first experience the feasibility and safety of radiofrequency catheter ablation (RFCA) of cavo-tricuspid isthmus (CTI) guided by KODEX-EPD imaging system in patients presenting with typical atrial flutter (AFL).

Methods

16 consecutive patients (mean age 68,46±7,8 years, 80% males) with diagnosis of AFL underwent RFCA guided by KODEX-EPD imaging system. In 15 patients the analysis performed during tachycardia showed a counter-clockwise activation. In 1 patient no tachycardia could be induced and the ablation was performed in sinus rhythm with fixed pacing from the coronary sinus. The KODEX-EPD imaging system was also used to guide ablation and to confirm persistent bidirectional block after ablation.

Results

Mean procedural time was 37,6±8,2 min, mean radiofrequency ablation time was 7,8±3,4 min, and mean fluoroscopy time was 2,1±1,2 min. All procedures were acutely successful with interruption of AFL during RFCA along the inferior CTI in 15 patients and achievement of the bidirectional conduction block in 16 patients proven by atrial pacing medial and lateral to the ablation line. There were no major procedural and 30-day complications. Over a mean follow-up of 18 months, we observed no recurrence of arrhythmia and no complications.

Conclusions

Our study shows that RFCA for AFL using the KODEX-EPD imaging system is feasible, safe, and effective.

Funding Acknowledgement

Type of funding sources: None.

Defibrillation testing of subcutaneous versus transvenous defibrillators in the clinical practice: a nationwide survey in Italy

Aims

According to current guidelines, defibrillation testing (DT) for efficacy can be omitted in patients undergoing transvenous implantable cardioverter–defibrillator (T-ICD) implantation. DT is still recommended for patients at risk for a high defibrillation threshold (e.g. hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, right-sided implantations) and for ICD generator changes. Moreover, a class I recommendation remains to perform DT during the implantation of subcutaneous ICD (S-ICD). The aim of the present survey was to analyze the current practice of DT during T-ICD and S-ICD implantations in Italy.

Methods

In March 2021, an ad hoc questionnaire on the current performance of DT and the standard practice adopted during testing was completed by 72 operators at Italian centers implanting S-ICD and T-ICD.

Results

48 (67%) operators reported never performing DT during de-novo T-ICD implantations, while no operators perform it systematically. The remaining respondents perform it in specific cases: right sided implantations (54%), poor signal sensing (46%), secondary prevention patients (42%), arrhythmic syndromes (13%), hypertrophic cardiomyopathy (8%). DT is never performed at T-ICD generator change. At the time of de-novo S-ICD implantation, DT is never performed by 9 (13%) operators and performed systematically by 48 (66%). The remaining operators perform DT in cases of: secondary prevention patients (73%), sub-optimal S-ICD placement (33%), non-compromised ejection fraction (33%) or obese patients (7%). DT is not performed at S-ICD generator change by 92% of operators. DT is conducted by delivering a first shock energy of 65J by 60% of operators, while the remaining 40% test lower energy values. The most frequently reported conditions for revising the system at the end of de- novo implantation procedure is high shock impedance (54%) and sub-optimal S-ICD placement or high PRAETORIAN score (50%). With adequately low shock impedance and optimal system placement, 37% of operators would accept a defibrillation margin <15J.

Conclusion

In current clinical practice, the vast majority of operators omit DT at T-ICD implantation, even when still recommended in the guidelines. DT is also frequently omitted at S-ICD implantation. We also report a wide variability among operators in the procedures followed during DT and in the criteria applied for defining the procedural success.

Funding Acknowledgement

Type of funding sources: None.

Local impedance characteristics and advanced mapping capabilities to better understand pulmonary veins reconnections during repeat AF ablation procedures: insight from the CHARISMA registry

Background

Detailed characterization of pulmonary veins (PV) reconnection during repeat AF ablation through high-density mapping (HDM) and local impedance (LI) algorithm is still lacking.

Purpose

We aimed to characterize PV gaps and underlying electrical activity during and after ablation of PVs in AF patients (pts).

Methods

Consecutive patients (pts) undergoing redo AF ablation from the CHARISMA registry with complete characterization of PV gaps (PVG) at 8 Italian centers were included. Rhythmia mapping system was used to map the left atrium and PVs before and after ablation. LI characteristics were collected through a RF ablation catheter equipped with a dedicated LI algorithm (DirectSense). A novel map analysis tool (Lumipoint) that automatically identifies split potentials and continuous activation was used sequentially on each PV component, in order to better assess PVG. Each PVG was characterized in terms of LI and its variations during the procedure. Ablation endpoint was PVI as assessed by entrance and exit block.

Results

Fifty PVGs were automatically identified through the Lumipoint tool in 23 cases, mostly at anterior sites (21, 42%), followed by posterior (15, 30%) and carina (10, 20%) sites. One PVG was identified in 7 (28%) pts, 2 gaps in 10 (43.5%) pts and >2 gaps in 6 (26.1%) pts. The mean LI at PVG sites was 111.3±12Ω prior to ablation: it was significantly higher than LI at scar tissue closer to PVG (99.3±8Ω, p<0.0001) but was significantly lower than LI at healthy tissue (120.8±11Ω, p=0.0015). The mean linear extension of PVGs detected through Lumipoint was significantly lower than the one recognized through voltage map (11.5±8 mm vs 13.3±9 mm, p=0.01) whereas was comparable to the one identified through conventional activation map (11.8±7 mm, p=0.1161 vs Lumipoint). Complete identification of the whole area of PVG was achieved in 31 (62%) and 42 (84%) cases through voltage and activation map, respectively whereas the identification was only partial in 18 (36%) and 7 (14%) cases, respectively. In 1 case both voltage and activation map failed to identify a PVG. No complications during the procedures were reported. All PVs were successfully isolated in all study pts.

Conclusion

Advanced mapping capabilities were useful to pinpoint the search for PVGs, enabling a more targeted ablation approach vs relying on voltage mapping. LI values correlated well with PVGs characteristics and they significantly differ from both scar and healthy tissue.

Funding Acknowledgement

Type of funding sources: None.

Early rhythm-control ablation therapy in preventing AF recurrences: insight from the CHARISMA Registry

Funding Acknowledgements

Type of funding sources: None.

Background

An early and comprehensive rhythm-control therapy emerges as a need to treat AF in an effective way and to improve the ablation outcomes, in terms of arrhythmia-free survival.

Purpose

We aimed to investigate the importance of timing of ablation in preventing AF recurrences.

Methods

153 consecutive patients (pts) undergoing AF ablation from the CHARISMA registry at 8 Italian centres were included. Ablations were guided by a novel radiofrequency ablation catheter with local impedance (LI)-sensing capability through a dedicated algorithm (DirectSense, Boston Scientific). Pts were grouped as early treated (ET) if the procedure was performed within 1 year after the first AF episode and as delayed treated (DT) if admitted for ablation after more than 1 year. The ablation endpoint was PVI as assessed by entrance and exit block. Post-ablation follow-up was scheduled at 3, 6 and 12 months. AF and atrial tachycardia (AT) recurrences were considered as long-term endpoint.

Results

Of the 153 pts enrolled (69.9% male, 59 ± 10 years, 61.4% paroxysmal AF, 38.6% persistent AF), 123 (80.4%) met Class I indications, 23 (15%) Class IIa indications and 7 (4.6%) Class IIb indications according to current ESC AF guidelines. The mean time to ablation procedure from the first AF episode was 1034 ± 1483 days. Eighty pts (52.3%) were included in ET group, whereas 73 pts (47.7%) in DT group. No differences were found between AF type in terms of ablation strategy (53.3% of the cases -52 out 94- were classified as ET for paroxysmal AF vs 47.5% of the cases -28 out 59- were ET for persistent AF, p = 0.4346). At the end of the procedures, all PVs had been successfully isolated in all study pts. During a mean follow-up of 366 ± 130 days, 18 pts (11.8%) suffered an AF/AT recurrence after the 90-day blanking period. Recurrences occurred mostly in the DT group compared to the ET one (13 out 73 -17.8%- vs 5 out 80 -6.3%-, p = 0.042) and the time to AT/AF recurrence was longer in the ET group (HR = 0.2876, 95%CI: 0.1029 to 0.8038; p = 0.0181). On multivariate logistic analysis adjusted for baseline confounders, only hypertension (HR = 4.66, 95%CI: 1.5 to 14.48, p = 0.0081) was independently associated with recurrences. An early rhythm-control therapy was associated with a low risk of recurrences beyond the hypertension risk factor, ranging from 2% (no hypertension and an ET ablation therapy) to 30.3% (with hypertension and a DT procedure) (Figure 1).

Conclusion

A LI-guided ablation strategy for PVI proved to be safe and effective and resulted in a very high recurrence-free rate. An early rhythm-control therapy in the absence of common risk factors was associated with the lowest rate of recurrences. Abstract Figure. AT/AF Recurrence

Impact of channels identification and ablation in ventricular tachycardia patients through high-density mapping: preliminary experience from an Italian registry

Funding Acknowledgements

Type of funding sources: None.

Background

Ventricular tachycardia (VT) ablation techniques in ischemic cardiomyopathy have evolved during the recent years. However, the long-term success rate remains disappointing. A technique based on channel identification and ablation through a novel automated algorithm may limit the extent of ablation needed and possibly lead to higher successful rate.

Purpose

To report preliminary data on feasibility and safety of a channel identification approach and to characterize late potentials (LPs) features using an ultra-high density mapping system with a novel analysis tool in ischemic VT procedures.

Methods

Consecutive patients (pts) indicated for ischemic VT ablation were enrolled in the CHARISMA study. A complete map of the left ventricle was performed prior and after ablation through the Rhythmia mapping system. For our purpose channels were defined as any signal activity bounded by anatomic and functional barriers and characterized through a novel map analysis tool (Lumipoint-LM-) that automatically identifies fragmented late potentials (LPs) and continuous activation was used on the whole ventricular substrate. Procedural endpoint was the elimination of all identified conducting channels (CCs) by ablation at the CC entrance and exit followed by abolition of any residual LPs inside the CC. The ablation endpoint was noninducibility.

Results

A total of 18 channels were identified through LM from 14 pts: 71.4% of the pts had 1 CC, 28.6% had 2 CCs. In the majority of the cases LPs where identified only inside CCs (57.1%), whereas in 6 cases (42.9%) LPs were present both inside and outside. The mean conduction time inside CCs was 50.3 ± 30ms, the mean CC length was 32.6 ± 17mm and the conduction velocity was 0.8 ± 0.5 mm/ms. LPs covered a mean area of 7.0 ± 5mm2 (ratio between LPs area and CCs’ area = 52.4 ± 33.7%). At voltage map analysis 1 CC was present in 78.6% of the cases (2 CCs in 21.4%). LPs were identified only inside CCs in 42.9% of the cases, both inside and outside in 50% and only outside in 7.1%. Healthy tissue (voltage level≥0.5mV) was prevalent (61.2 ± 13.8%), followed by intermediate voltage areas (0.5-0.05mV; 37.5 ± 13.7%) and very low voltage areas (<0.05mV; 1.2 ± 2%). LPs were found mostly at intermediate voltage areas (54.1 ± 31.7% of the covered area; 39.1 ± 28.4% at healthy tissue and 6.8 ± 17.8% at very low voltage areas). Agreement in CCs identification between advanced analysis through LM and voltage map was fair (9/14 with complete agreement). In 3 cases voltage map overestimated LPs areas, in 2 cases failed to fully identify LPs. All CCs’ entrance and exit were successfully ablated and abolition of any residual LPs inside the CC was achieved in all pts. No complication occurred. Noninducibility was achieved in all the cases.

Conclusions

In our preliminary experience, a new channel identification approach through the advanced Lumipoint algorithm seems to be safe, feasible and effective at least in the acute setting of ischemic VT ablation.

Near zero fluoroscopy in cryoballoon catheter ablation in patients with atrial fibrillation using the new KODEX-EPD imaging system

Funding Acknowledgements

Type of funding sources: None.

Background. Fluoroscopy is commonly used in cryoballoon catheter ablation for pulmonary vein (PV) isolation procedures in patients with atrial fibrillation (AF).

Objective The purpose of this study was to verify the feasibility of a new dielectric imaging system in reducing the radiation exposure during cryoballoon ablation in patients with AF.

Methods We enrolled 26 consecutive patients with paroxysmal AF: 13 patients underwent the procedure under fluoroscopy guidance before the new system introduction, while 13 patient underwent the procedure under fluoroscopy and KODEX-EPD system guidance with its occlusion tool software. After transseptal access a detailed image reconstruction of left atrium and PVs was achieved with the Achieve octapolar circular mapping catheter and the cryoablation was performed with the Arctic Front Advance cryoballoon.

Results Total time of the procedure was comparable between the two groups (90.15 ± 28.67 vs 80.77 ± 17.17 using KODEX-EPD, p = 0.34), while fluoroscopy time was significantly lower in the group using KODEX-EPD (16.92 ± 8.96 vs 5.54 ± 2.06, p < 0.01). Acute isolation was achieved in all PVs. No 30 days complication was observed.

Conclusion This is the first study that demonstrates the feasibility of a reduce fluoroscopy workflow using the novel KODEX-EPD system in a cryoballoon procedure. Abstract Figure. Fluoroscopy time

The magnitude and the course of local impedance drop to guide successful AF ablation: insight from an Italian registry

Funding Acknowledgements

Type of funding sources: None.

Background

It has been demonstrated that an ablation strategy based on local impedance (LI) algorithm is helpful in guiding successful ablation of atrial fibrillation (AF) cases. How the magnitude and the course of LI drop could impact the effectiveness of ablation has to be proved.

Purpose

We aimed to evaluate LI drop characteristics in predicting effective radiofrequency (RF) ablation of consecutive AF cases.

Methods

Consecutive patients undergoing AF ablation at 8 Italian centers were included in the CHARISMA registry. A RF ablation catheter equipped with mini-electrodes technology and a dedicated algorithm was used to measure LI and to guide ablation. For our purpose, we defined the time to drop (τ) as the time for the first deflection of LI drop to the plateau. RF applications were targeted to a LI drop of 10 Ω and were stopped when a maximum cut-off LI drop of <40 Ω was observed. Successful single RF ablation was defined according with a reduction of signal voltage by at least 50% and inability to capture local tissue on pacing. The ablation endpoint was PVI as assessed by entrance and exit block. Follow-up were scheduled at 3, 6 and 12 months post-ablation.

Results

153 consecutive patients (61% paroxysmal AF, 39% persistent AF) were enrolled in the study. 3556 point-by-point first-pass RF applications of >10 s duration were performed around PVs. The mean LI drop was 13 ± 8Ω, the mean τ was 18.7 ± 13s and the median LI drop/τ was 0.67 [QI-QIII, 0.37 – 1.17] Ω/s. Both absolute drops in LI and LI drop/τ were greater at successful ablation sites (n = 3122, 88%) than at ineffective ablation sites (n = 434, 12%) (14 ± 8Ω vs 6 ± 4Ω, p < 0.0001 for LI; 0.73[0.41–1.25]Ω/s vs 0.35[0.22–0.59]Ω/s for LI drop/τ, p < 0.0001). Every 5-point increment in LI drop was associated with successful ablation, with an OR of 3.13 (95%CI: 2.7 to 3.6, p < 0.0001), reaching the highest point when a value larger than 15 Ω was observed (99.9% of acute success). A significant trend was observed from lower to higher LI drop/τ values and a value greater than 0.65 Ω/s (best cut-off value on the basis of the ROC analysis) was significantly associated with successful RF delivery with an OR of 5.54 (95%CI: 4.31 to 7.11, p < 0.0001). No complications occurred during and after procedures. At 1-year follow-up, the AF recurrence rate was 12% after the 90-day blanking period.

Conclusions

The magnitude and time-course of the LI drop during RF delivery were associated with effective lesion formation. This ablation strategy for PVI guided by LI technology proved safe and effective, and resulted in a very low rate of AF recurrence over 1-year follow-up.

Minimal fluoroscopic approaches and factors associated with radiation dose when high-definition mapping is used for supraventricular tachycardia ablation: insight from the CHARISMA registry

Funding Acknowledgements

Type of funding sources: None.

Background

Limited data exist on factors associated with radiation exposure during ablation procedures when a high definition mapping technology is used.

Purpose

To report factors associated with radiation exposure and data on feasibility and safety of a minimal fluoroscopic approach using the Rhythmia mapping system in supraventricular tachycardia (SVT) ablation procedures.

Methods

Consecutive patients indicated for arrhythmia ablation were enrolled in the CHARISMA study at 12 centers. We included in this analysis consecutive right-side procedures performed through a minimal fluoroscopy approach with the Rhythmia mapping system were analyzed. A 3D geometry of chambers of interest was reconstructed on the basis of the electroanatomic information taken from the mapping system. Fluoroscopy was used only if deemed necessary. The effective dose (ED) was calculated using accepted formula. For our purpose high dose exposure was defined as an ED greater than the median value of ED of the population exposed to radiation.

Results

This analysis included 325 patients (mean age = 56 ± 17 years, 57% male) undergoing SVT procedures (152 AVNRT, 116 AFL, 41 AP and 16 AT). During the study, 27481 seconds of fluoroscopy was used (84.6 ± 224 seconds per procedure), resulting in a mean equivalent ED of 1.1 ± 3.7 mSv per patient. The mean reconstructed RA volume was 99 ± 54 ml in a mean mapping time of 12.2 ± 7 min. The mean number of radiofrequency ablations (RFC) to terminate each arrhythmia was 9.4 ± 9 (mean RFC delivery time equal to 6.7 ± 6 min). 192 procedures (59.1%) were completed without any use of fluoroscopy; during the remaining 133 procedures (39.9%), 206.6 ± 313.4 seconds of fluoroscopy was used (median ED = 1.2 mSv). In a minority of the cases (n = 25, 7.7%) the fluoroscopy time was higher than 5 minutes (median ED = 6.5 mSv), whereas radiologic exposure time greater than 1 minute occurred in ninety cases (27.7%, median ED = 2.1 mSv). On multivariate logistic analysis adjusted for baseline confounders the RFC application time (OR = 1.0014, 95%CI: 1.0007 to 1.0022; p = 0.0001) was independently associated to an ED greater than 1.2 mSv, whereas female gender had an inverse association (0.54, 0.29 to 0.98; p = 0.0435). Acute success was reached in 97.8% of the cases. During a mean of 290.7 ± 169.6 days follow-up, no major adverse events related to the procedure were reported. Overall, the recurrence rate of the primary arrhythmia during follow-up was 2.5%.

Conclusions

In our experience, arrhythmias ablation through minimal fluoroscopy approach with the use of a novel ablation technology is safe, feasible, and effective in common right atrial arrhythmias. High-dose exposure occurred in a very limited number of cases, without any reduction of the safety and acute and long-term effectiveness profile.

Impact of ablation index settings on pulmonary vein reconnection

PURPOSE

Ablation index (AI) is a radiofrequency lesion quality marker. The AI value that allows effective and safe pulmonary vein isolation (PVI) is still debated. We evaluated the incidence of acute and late PV reconnection (PVR) with different AI settings and its predictors.

METHODS

The Ablation Index Registry is a multicenter study that included patients with paroxysmal/persistent atrial fibrillation (AF) who underwent first-time ablation. Each operator performed the ablation using his preferred ablation catheter (ThermoCool® SmartTouch or Surround Flow) and AI setting (380 posterior-500 anterior and 330 posterior-450 anterior). We divided the study population into two groups according to the AI setting used: group 1 (330-450) and group 2 (380-500). Incidence of acute PVR was validated within 30 min after PVI, whereas the incidence of late PVR was evaluated at repeat procedure.

RESULTS

Overall, 490 patients were divided into groups 1 (258) and 2 (232). There was no significant difference in the procedural time, fluoroscopy time, and rate of the first-pass PVI between the two study groups. Acute PVR was observed in 5.6% PVs. The rate of acute PVR was slightly higher in group 2 (64/943, 6.8%, PVs) than in group 1 (48/1045, 4.6% PVs, p = 0.04). Thirty patients (6%) underwent a repeat procedure and late PVR was observed in 57/116 (49%) PVs (number of reconnected PV per patient of 1.9 ± 1.6). A similar rate of late PVR was found in the two study groups. No predictors of acute and late PVR were found.

CONCLUSION

Ablation with a lower range of AI is highly effective and is not associated with a higher rate of acute and late PVR. No predictors of PV reconnection were found.

A novel local impedance algorithm to guide effective pulmonary vein isolation in AF patients: 1-year outcome from the CHARISMA Study

Background

Recently, a novel technology able to measure local tissue impedance (LI) providing a measure of tissue characteristics aimed at validating confidently ablation endpoints has become available for clinical use.

Purpose

We report the outcomes of our acute and long-term clinical evaluation of this algorithm in consecutive atrial fibrillation ablation cases.

Methods

Consecutive patients (pts) undergoing AF ablation at 6 Italian centers were included in the CHARISMA registry. A novel RF ablation catheter and a dedicated algorithm were used to measure LI through the distal catheter's electrode. The ablation was guided by looking at the magnitude and time course of impedance drop during RF delivery. The maximum distance between each ablation spot (center-to-center) was suggested to be ≤4 mm. RF applications were targeted to a LI drop of 10 Ω and RF applications were stopped when a maximum cutoff LI drop of <40 Ω was observed. Successful single RF ablation was defined according with a reduction of signal voltage (RedV) by at least 50% and inability to capture local tissue on pacing. Ablation endpoint was PVI as assessed by entrance and exit block. Post-ablation, all pts were monitored with ambulatory event monitoring, as well as Holter monitoring at 3, 6, and 12 months post-ablation. Additional ECG monitoring was performed as indicated by patient symptoms.

Results

A total of 1914 point by point first pass RF applications >10 s performed around PVs were analyzed from 98 pts (mean age = 61±11 years, 69% male, 55% paroxysmal AF, 45% persistent AF, 60% de novo procedures, 40% redo procedures). The mean LI was 105±15Ω prior to ablation and 92±13Ω after ablation (p<0.0001, mean absolute LI drop of 12.7±8Ω) during a median RF delivery time of 22 [17–31] sec. Effective ablation spots (88%) showed a higher absolute impedance drop (13.6±8Ω at effective RedV vs 6±3Ω at ineffective RedV, p<0.0001) compared with ineffective sites (12%). No steam pops or complications, including atrio-esophageal fistula or tamponade were reported during or after the procedures. At the end of the procedures all PVs were successfully isolated in all study pts. During a median follow-up of 369 [287–446] days, 13 pts (13.2%) developed an AF/AT recurrence after the 90-days blanking period (9.2% with paroxysmal vs 18% with persistent AF, p=0.239; 8.5% for de novo vs 20.5% for redo procedures, p=0.127). The time to recurrence was comparable among AF type (HR=1.97; 0.66 to 5.86; log-rank p=0.2265 for persistent vs paroxysmal AF) and procedural type (HR=2.56; 0.84 to 7.82; log-rank p=0.087 for redo vs de novo procedure)

Conclusions

In our experience, the magnitude of the LI drop during RF delivery was associated with effective lesion formation. An ablation strategy for PVI guided by LI technology was safe and effective, and resulted in a very low recurrence rate of AF at 1-year follow-up irrespective of paroxysmal/persistent AF type or de novo/redo procedure.

Funding Acknowledgement

Type of funding source: None

Near zero fluoroscopy cryoballoon catheter ablation in patients with atrial fibrillation using a novel dielectric imaging system

Background

Fluoroscopy is commonly used in cryoballoon catheter ablation for pulmonary vein (PV) isolation procedures in patients with atrial fibrillation (AF).

Purpose

The purpose of this study was to verify the feasibility of a new dielectric imaging system in reducing the radiation exposure during cryoballoon ablation in patients with AF.

Methods

We enrolled 40 consecutive patients with paroxysmal AF: 20 patients underwent the procedure under fluoroscopy guidance before the new system introduction, while 20 patient underwent the procedure under fluoroscopy and a new dielectric imaging system guidance with its occlusion tool software. After transseptal access a detailed image reconstruction of left atrium and PVs was achieved with an octapolar circular mapping catheter and the cryoablation was performed with a cryoballoon catheter.

Results

Total time of the procedure was comparable between the two groups (90.15±28.67 vs 80.77±17.17 using the dielectric imaging system, p=0.34), while fluoroscopy time was significantly lower in the group using the new dielectric imaging system (16.92±8.96 vs 5.54±2.06, p<0.01). Acute isolation was achieved in all PVs. No 30 days complication was observed.

Conclusion

This is the first study that demonstrates the feasibility of a reduce fluoroscopy workflow using the novel dielectric imaging system in a cryoballoon procedure.

Funding Acknowledgement

Type of funding source: None

Novel occlusion tool software for pulmonary vein occlusion verification in atrial fibrillation cryoballoon ablation

Background

Optimal pulmonary vein (PV) occlusion, checked with selective contrast injection, is mandatory to obtain an effective PV isolation with a cryoballoon.

Purpose

The purpose of this study was to verify the feasibility of a new dielectric sensing system in assessing PV occlusion during cryoballoon ablation in patients with atrial fibrillation (AF).

Methods

We enrolled 25 consecutive patients with paroxysmal or persistent AF. After transseptal access a detailed image reconstruction of left atrium and PVs was achieved with a decapolar circular mapping catheter and a novel dielectric imaging system. The degree of PV occlusion with the inflated cryoballoon catheter was verified by a new occlusion tool software of the dielectric imaging system and compared to the angiography with dye injection in each PV.

Results

A total of 114 PV cryoballoon occlusion were tested. The new occlusion tool software showed a 91.7% sensitivity and 81.5% specificity in assessing a complete PV occlusion verified with dye injection. The positive predictive value was 84.6% and the negative predictive value was 89.8%. Acute isolation was achieved in all PVs. No 30 days complications were observed.

Conclusion

This is the first study that demonstrates the feasibility of a new occlusion tool software, using the novel dielectric imaging system, in verifying the degree of PV occlusion during cryoballoon ablation.

Funding Acknowledgement

Type of funding source: None

Minimal fluoroscopy approach in current clinical practice with a novel ablation technology for supraventricular tachycardia: a large multicenter experience from an Italian registry

Background

Electrophysiological studies and ablation procedures expose both physicians and patients to a large amount of radiation. Most of 3-D mapping systems provide improved tracking of catheters, possibly allowing relevant reductions in radiation exposure. No data exists on the ability of the Rhythmia mapping system to minimize fluoroscopy time and dose.

Purpose

To report preliminary data on feasibility and safety of a minimal fluoroscopic approach using the Rhythmia mapping system in supraventricular tachycardia (SVT) procedures.

Methods

Consecutive patients indicated for arrhythmia ablation were enrolled in the CHARISMA study at 12 centers. For our purpose consecutive right-side procedures performed through a minimal fluoroscopy approach with the Rhythmia mapping system were analyzed. A 3D geometry of chambers of interest was reconstructed on the basis of the electroanatomic information taken from the mapping system. Fluoroscopy was used only if deemed necessary.

Results

This analysis included 266 patients (mean age = 57±17 years, 57% male) undergoing SVT procedures (120 AVNRT, 91 AFL, 32 AP, 11 AT and 12 other right atrial procedures). In all cases, diagnostic EP and ablation catheters were positioned using a low fluoroscopic electroanatomic guided approach. The mean fluoroscopy time needed for each procedure was 55±128 s. The median reconstructed RA volume was 92 [63–131] ml in a median mapping time of 11 [7–17] min. The median number of radiofrequency ablations to terminate each arrhythmia was 6 [3–12] (total RF delivery time of 291 [180–505] s). Sixty-five percent of the procedures (n=174) were completed with less than 10 s of fluoroscopy. Low fluoroscopy approach with less than 10 s (minimal fluoroscopy approach) was most frequently obtained in case of AVNRT (91, 76%) compared to other arrhythmias' ablation (83, 57%, p=0.001) Achievement of a minimal fluoroscopic approach was not affected by operator's experience (65% vs 66%, p=1.00, respectively within physician with more or less of 10 years of active practice), whereas it was affected by presence of a fellow in training during the procedure (72% without fellow vs 26% with fellow, p<0.0001). A 100% rate of acute success was observed, and no procedure-related complications occurred. At multivariate logistic regression analysis adjusted for baseline confounders, both the total number of RF ablations (OR: 0.93 (95% CI:0.88 to 0.96; p=0.0053) and the presence of a fellow in training during the procedure (OR: 0.29; 95% CI: 0.1 to 0.87; p=0.0278) had an inverse association to the achievement of a minimal fluoroscopic approach.

Conclusions

In our preliminary experience, arrhythmias' ablation through minimal fluoroscopy approach with the use of a novel ablation technology seems to be safe, feasible, and effective in common right atrial arrhythmias. Use of fluoroscopy can be dramatically reduced in most cases, without any reduction of the safety and acute effectiveness profile.

Funding Acknowledgement

Type of funding source: None

P441Targeted ablation of residual luminal pulmonary vein potentials through high density mapping: preliminary results from the CHARISMA registry

Background

A high incidence of pulmonary vein (PV) reconnection has been reported in patients (pts) with clinical recurrences of AF. Low-voltage activity beyond PVs (e.g. antral activity) may contribute to ablation failures in the long term. Detailed characterization of PV antra through high density mapping (HDM) and automated algorithm is still lacking. 

Purpose

to characterize PV gaps and the low-voltage activity in tissue such as the PV antra during and after ablation of PVs in AF pts. 

Methods

Consecutive pts undergoing AF ablation from the CHARISMA registry with complete characterization of residual PV antral activity were included. A complete map of the left atrium and PVs was performed prior and after ablation through the Rhythmia HDM system. A novel map analysis tool (Lumipoint - LM -) that automatically identifies split potentials and continuous activation was used sequentially on each PV component, in order to assess the presence of gaps (PVG) and residual potential within the antral scar (RAP, defined as any low voltage high frequency fractionated signal propagating within the antral scar without conduction into the vein) and characterize electrical propagation. After ablation we reassessed with repeat voltage and propagation maps that electrical quiescence was achieved. Ablation endpoint was PV isolation. 

Results

Thirty-six cases of AF ablation were analyzed (11 de novo, 25 redo). A total of 36 PVG in 13 (36%) patients were detected after remap (1 case of de novo) or initial map of redo patients (12 cases). A total of 34 RAP in 20 cases (56%) were found: 4 (36%) cases of de novo (all after ablation and remap) and 16 (64%) cases of redo (all after initial map). In 7 (19%) cases we found at least one RAP in pts with complete absence of PV conduction. 100% of PVG (n = 36) and 89% of RAP (n = 29) were fully detected though a first pass automated annotation. In 5 RAPs (11%) an additional temporal consistency of low-voltage signal relative to neighboring activation was needed due to the very low voltage EGM (≤0.1 mV). PVGs were more common at right PV sites (n = 26, 72%) and anterior PV sites (n = 20, 55.6%) whereas RAPs were detected more frequently at left PV sites (n = 20, 59%) and anterior PV sites (n = 21, 62%). RAP showed a lower median voltage compared with PVG (0.22[0.2-0.3]mV for RAP vs 0.97[0.6-1.3]mV for PVG, p < 0.0001) whereas the median number of EGM peaks were higher (6.5[5-8] for RAP vs 3[2-4] for PVG, p < 0.0001). No complications during the procedures were reported. The acute procedural success was 100%, with all PVs successfully isolated and RAPs completely abolished in all study pts. 

Conclusion

In our preliminary experience, local vulnerabilities in antral lesion sets were commonly discernible using HDM system both in de novo or redo patients when no PV conduction was present. The applied workflow seemed to be useful to quickly pinpoint and accelerate the search of local PV activity or concealed low-voltage activity.

P1020Persistent AF patients with limited areas of low voltage have a similar benefit from pulmonary vein isolation as compared to paroxysmal AF patients: insight from the SMOP study

Background

Pulmonary vein isolation (PVI) performed with radio-frequency catheter ablation (CA) is an effective therapy for atrial fibrillation (AF). However previous data have suggested that PVI is less effective in persistent (PER) vs. paroxysmal (PAR) AF. Atrial fibrosis and scar, indeed, are an important substrate involved in persistent AF, and some author correlate them to an increased rate of recurrences after CA. For this reason several adjunctive ablation strategies have been suggested for invasive treatment in PER AF pts. However, there is a lack of evidence on their effectivness in current literature.

Objective

the aim of our study was to assess the rate of AF recurrences in PAR and PER AF patients after a first pulmonary vein isolation (IVP) procedure, and their relationship with low voltage areas of the left atrium assessed by means of high density mapping performed before CA.

Methods

we analyzed 214 patients of the SMOP-AF study (Substrate Mapping as Outcome Predictor in Atrial Fibrillation Ablation), a prospective multi-centric registry enrolling patients with both PAR and PER AF undergoing a first radio-frequency CA procedure aimed to obtain permanent PVI . High-density mapping was performed in sinus rhythm using the CARTO system before PVI. Areas with less than 0,5 mV on mapping were defined as low voltage zone (LVZ); LVZ was indexed on the atrial area. Comparisons were made by cross-tables and Chi-square test or Student T test.

Results

Patients with PER AF (n = 44, 21%) were older (63 ± 9 vs 58 ± 10 yrs, p = 0.01), but notably with no difference in LVEF and atrial dimensions as compared to pts with PAR AF. In addition no statistical difference was observed in procedural variables, except for a greater LVZ area on atrial mapping (8 ± 18 % vs. 5 ± 15 %, p = 0.04) and a longer p wave duration (115 ± 21 msec vs. 103 ± 18 msec, p = 0.01) in pts with PER AF. The incidence of recurrence in the overall population was 15.3% at 3 months and 13.7% from 3 to 12 months: there was no statistical difference in success-rate between PER and PAR pts (respectively 79,5% vs 86% p value = 0.315 in blanking period and 85,3% vs 86,5% p value = 0.8 at 3-12 months follow-up). No statistical difference was observed for ablation variables (number of lesion, contact force, force time integral) in pts with vs. without recurrences.

Conclusion

Our study showed that pulmonary vein isolation alone seems to be as effective in paroxismal and persistent AF patients with low degree of left atrial fibrosis. Our data call into question the idea that PVI alone is not effective in PER AF. High density mapping of the LA could help to identify a subset of PER AF patients with a limited extension of low voltage areas (i.e around 10% of the overall LA surface) that could benefit from PVI without adjunctive ablation strategies. Our data needs to be confirmed in a longer follow-up.

853Could baseline electrical parameters be a marker of arrhythmia occurrence and poorer prognosis in implantable cardioverter defibrillator patients?

Funding Acknowledgements

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Background/Introduction: Parameters routinely measured during cardiac devices implantation also depend on bioelectrical properties of the myocardial tissue.

Purpose

To explore the potential association of electrical parameters with clinical outcomes in implantable cardioverter-defibrillator (ICD) and cardiac resynchronization therapy defibrillators (CRT-D) recipients.

Methods

In the framework of the Home Monitoring Expert Alliance, baseline electrical parameters for all implanted leads were compared by occurrence of all-cause mortality, adjudicated ventricular arrhythmia (VA) and atrial high rate episode lasting ≥7 days (7day-AHRE).

Results

In a cohort of 2,976 patients (58.1% ICD) with a median follow-up of 25 months, events rates were 3.1/100 patient-years for all-cause mortality,  18.1/100 patient-years for VA and 8.9/100 patient-years for 7day-AHRE.

At univariate analysis baseline shock impedance was consistently lower in groups with events than in those without, with a 40 Ohm cut-off  better identifying patients at high risk, but at multivariable analysis the adjusted-hazard ratios (HRs) lost statistical significance for any endpoint.

Baseline atrial sensing amplitude during sinus rhythm was lower in patients with 7-day AHRE as compared to those without (2.40 [IQ: 1.62-3.71] Vs 3.50 [IQ: 2.35-4.66] mV, p < 0.01). The adjusted-HR for 7-day AHRE in patients with atrial sensing >1.5 mV versus those with values ≤1.5 mV was 0.44 (95% CI:0.27-0.72), p = 0.001.

Conclusion

Despite in patients with events a lower baseline shock impedance was observed at univariate analysis, the association lost statistical significance at multivariable analysis. Conversely, low sinus rhythm atrial sensing (≤1.5 mV) measured with standard transvenous leads could identify subjects at high risk of long-lasting atrial arrhythmia.

Abstract Figure. AHRE occurrence by atrial sensing

P1448Ablation of cti-dependent flutter using a novel advanced mini-electrodes technology: preliminary results from Leonardo registry

Funding Acknowledgements

NO FUNDING

OnBehalf

LEONARDO study group

Background

Ablation of cavotricuspid isthmus (CTI) represents the standard therapeutic approach for the creation of bidirectional conduction block (BDB) across the isthmus and the prevention of recurrences, yet recurrence of arrhythmia is common.

Objective

To evaluate the acute and long-term outcome of CTI ablation through a novel ablation catheter equipped with three radially distributed mini-electrodes (ME) compared with standard ablation catheter technology (ST).

Methods

Atrial Flutter Ablation in a Real World Population (LEONARDO) is a prospective, multicenter cohort study aimed at providing an estimate of acute to long-term outcome in a large population of pts indicated for AFL ablation from 2015 to 2017. The procedural endpoint was the creation of a BDB. Presence of widely split double potentials (DP) along the ablation line and assessment of the atrial activation sequence (AAS) were used as criteria for complete BDB. Recurrence of AFL and complications were assessed at 12-month follow-up.

Results

  205 consecutive pts undergoing typical AFL ablation were included (74% male, 50.6% with history of AF, median of 7[4–11] ablation lesions, median ablation time of 20[10-30] min). Complete BDB was achieved in 175 (85.4%) pts (10 pts had DP only criterion, 19 pts had AAS only criterion whereas in 1 pt we failed to reach a BDB). 15 (7.3%) pts experienced AFL recurrence during follow-up. 102 pts (49.8%) underwent ablation procedure with ME catheters whereas 103 (50.2%) pts were treated by ST catheters. The median number of lesions/pt was significantly lower in the ME group compared to the ST one (4[3-6] vs 8.5[6-12], p < 0.0001), whereas no differences were found in terms of fluoroscopy time (10.5[7-15] min vs 10[5.8 ± 15] min, p = NS) or ablation time (22.5[10-30.5] min vs 18[10-26] min, p = NS). No complications were reported. The acute procedural success was comparable between groups (81.4% vs 89.2%, p = NS) whereas the time to AFL recurrence was significantly longer among pts targeted with ME catheters (HR = 0.343; 0.12 to 0.97; log-rank p = 0.044).

Conclusions

In our preliminary experience, the use of the ME technology seemed safe and effective. It resulted in fewer lesions/pt and a lower AFL recurrence rate at 1-year follow-up compared with ST ablation catheters.

P531Cardiac resynchronization therapy in patients with permanent atrial fibrillation: insights from the HMEA database

Funding Acknowledgements

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Background/Introduction: The benefits of cardiac resynchronization therapy with defibrillator (CRT-D) in heart failure are well established. However, a gap of evidence is still present for patients with permanent atrial fibrillation (perm-AF)

Purpose

To investigate outcomes of CRT-D patients with perm-AF in terms of appropriate shock for ventricular arrhythmia and all-cause mortality in a long-term time horizon. 

Methods

We used the Home Monitoring Expert Alliance (HMEA) database, a nationwide data repository of daily remote monitoring transmissions. The episodes with delivered shock were adjudicated by a board of 3 electrophysiologists.

Results

Among 1226 CRT-D patients (mean age 71.2 ± 10.0 years; 75.5% males), 276 (22.5%) had perm-AF at device implantation. These patients had more frequently rate responsive function (19.7% vs 64.1%) and higher basic rate (median value 60 bpm vs 70 bpm) as compared to all other patients (p < 0.001). The CRT pacing percentage calculated over the first 2 months was slightly lower for perm-AF patients (median value 96.0% vs 98.8%, p < 0.001).

At 5-year appropriate shock incidence was 34.2% (95% confidence interval [CI], 25.1%-45.3%) for perm-AF and 19.9% (15.6%-25.1%) for all other patients. All-cause mortality was 27.7% (17.7%-41.8%) for perm-AF and 15.6% (12.2%-19.9%) for all other patients. 

The age- and sex-adjusted hazard ratio between perm-AF and all other patients was 1.81 (95% CI: 1.25-2.64, p = 0.002) for appropriate shock and 0.92 (95% CI: 0.57-1.50, p = 0.748) for all-cause mortality.

Conclusion

Although a higher incidence of appropriate shock, perm-AF at the time of CRT-D implantation was not associated with increased long-term mortality,

Abstract Figure. Appropriate shock and mortality

P1452Low fluoroscopy approach with a novel ablation technology in right side procedures: a large multicenter experience from the CHARISMA registry

Funding Acknowledgements

NO FUNDING

Background

Electrophysiological studies and ablation procedures expose both physicians and patients to a significant amount of radiation. Nowadays, most of 3-D mapping systems allow for improved tracking of catheters with possible reduction in radiation exposure. No data exists on the ability to minimize fluoroscopy time and dose while using the Rhythmia mapping system.

Purpose

To report preliminary data on feasibility and safety of a low fluoroscopic approach using the Rhythmia mapping system in SVT procedures.

Methods

The CHARISMA study is a non-randomized, multicenter, prospective study in which consecutive patients indicated for arrhythmia were enrolled. For our purpose consecutive right-side procedures performed through a low fluoroscopy approach with the Rhythmia mapping system were analyzed. The mapping system was used to create the 3D geometry of chambers of interest and anatomic reference points and to visualize the catheters from the beginning to the end of the procedure. Fluoroscopy was used only if deemed necessary.

Results

204 unselected consecutive cases of SVT from 11 centers were included in the study (mean age = 55 ± 18 years, 53% male, 85 AVNRT, 75 AFL, 28 AP, 9 AT and 7 other right atrial procedures). In all the cases, diagnostic EP and ablation catheters were positioned using only the low fluoroscopic guided mapping approach. During the study, a total of 7157 s of fluoroscopy was needed in 204 patients (51 ± 137 s per procedure). One hundred fourty-one procedures (69%) were completed with less than 10 seconds of fluoroscopy, whereas in 169 (83%) of the cases the fluoroscopy time was lower than 60 seconds. Low fluoroscopy approach with less than 10 seconds was less frequently obtained in case of AFL (46, 61.3%) compared to AVNRT ablation (65, 76.5%, p = 0.041) whereas no differences were found comparing with AP (21, 75%, p = 0.248). The median reconstructed RA volume was 94[65-133] ml in a median mapping time of 11 [6-16] min. The median number of radiofrequency ablations to terminate each arrhythmia was 5 [3-12] (total RF delivery time of 293 [180-505] sec). A 100% rate of acute success was observed in our case series. No complications occurred.

Conclusions

In our preliminary experience, arrhythmias ablation through low fluoroscopy approach and the use of a novel ablation technology seems to be safe, feasible, and effective in common right atrial arrhythmias. Use of fluoroscopy can be nearly avoided in most cases, without any reduction of the safety and effectiveness profile.

P2592Combining home monitoring temporal trends and baseline patient risk profile for predicting impending heart failure hospitalizations. Results from the SELENE HF (BIO.Detect HF IV) study

Background/Introduction

The lack of a validated method to efficiently combine information provided by Remote Monitoring (RM) of implantable defibrillators (ICD) and patient clinical profile has limited the use of RM in the prevention of worsening heart failure episodes.

Purpose

Our objective was to develop and validate an index combining RM temporal trends and a baseline risk score for predicting the first HF hospitalization after device implantation.

Methods

We prospectively enrolled 918 patients (81% male, median age 69, interquartile interval [QI], 61/76; Seattle Heart Failure Score [SHFS], 0.17, QI, −0.40/0.75) with indication to ICD (56%), or ICD with cardiac resynchronization therapy (44%). The Home Monitoring (HM) system was activated in all patients after implant to collect several technical and HF-related variables daily. Investigators were blinded to HM reports, and only received automatic alerts for critical technical issues. The primary endpoint was the first adjudicated HF hospitalization. The cohort was a posteriori 1:1 randomized in derivation and validation groups stratified by device type and primary endpoint occurrence. The SHFS was used for baseline risk assessment.

Results

During a median follow-up of 23 months (QI, 14/36), 62 first HF hospitalizations were adjudicated. In the derivation group, the index was constructed by combining the SHFS and temporal trends of 24-hour and rest mean heart rates, ventricular ectopic beat frequency, arrhythmic atrial burden, heart rate variability, physical exercise, and thoracic impedance. Variable selection was based on an automatic stepwise procedure, after applying appropriate transformations in variable-specific time frames to maximize the area under the receiver operating characteristics curve (AUC). The resulting index was associated to an AUC of 0.88 and an Odds Ratio of 2.72 (confidence interval [CI] 1.97–3.75, p<0.001) for index unitary increase. In the index validation test, first HF hospitalizations were predicted with a sensitivity of 73.3% (CI, 54.1%-87.7%), a median alerting time of 55 days (QI, 20/68), false alert rate of 0.75 (CI, 0.70–0.81) patient-year, and 95.1% false-alert-free days.

Conclusion

HM temporal trends of selected variables and the SHFS may be combined to timely and efficiently predict the first HF hospitalization after implant, with less than 1 expected per-patient false alert per year.

Acknowledgement/Funding

BIOTRONIK SE & Co. KG, Berlin, Germany

P1896Single-procedure success-rate of pulmonary vein isolation using point-by-point tagging lesions algorithm based on contact force technology: preliminary results of the multicentric SMOP study

Background

Pulmonary veins isolation (PVI)is an effective therapy for atrial fibrillation (AF), recommended by current guidelines. However, recurrences after first radio-frequency (RF) catheter ablation (CA) are still high. PV reconnection could be due to ineffective transmural lesions; automated ablation lesion tags (the VisiTag algorithm) based on predefined parameters of catheter stability and contact force (CF) have been developed to allow the detection of ineffective ablation lesion, nevertheless there is a lack of multicenter studies exploring this technology.

Objective

the aim of our study was to assess the rate of recurrence after a first PVI procedure in a large, multicentric Italian population and to explore the efficacy of Visitag algorithm (CARTO 3) used to guide RF ablation of AF.

Methods

we analyzed 214 patients of the SMOP-AF study (Substrate Mapping as Outcome Predictor in Atrial Fibrillation Ablation), a prospective multi-centric study enrolling patients with paroxysmal and persistent AF undergoing a first PVI procedure after an high-density mapping during sinus rhythm. During the procedure, ablation was guided by an automated annotation system in which tag based on predefined parameters were displayed real-time in each lesion site on the electroanatomical map. Visitag settings for the catheter position stability were a 2,5 mm distance limit for at least 7 sec and a minimum CF of 5 g over 30% of the ablation and a FTI>400 g*s. Where available (n=106, 49.5%), Ablation Index (AI), which also incorporates information on delivered RF power, was used instead of FTI to guide RF ablation with a threshold range of 400–550 for anterior/roof and 330–420 for posterior/inferior segments. Minimum and mean contact force, time and power values for each RF-lesion were recorded while both FTI and AI values were calculated automatically by the CARTO system. Comparison between groups were made by cross-tables, Mann-Whitney or Student T test as appropriated.

Results

the mean age of the enrolled population was 59±9 years, left ventricular ejection fraction was 59±9%. AF was paroxysmal in 89.7%, persistent in 10.3% of the patients and refractory to at least one anti-arrhythmic drug in 86.4% of the population. At 3 months follow-up 85% of the patients were free from AF recurrences and the success rate increased to 90.8% at 3–6 months, and 86.3% at 3–12 months follow-up. The mean ablation time was shorter in AI-guided vs. FTI-guided procedures (31±9 vs 46±29 min; p<0.001). There was a trend toward a reduction in AF recurrences when AI vs. FTI was used, both at 6 and 12 months (respectively 5,4% vs 13.6%; p 0.06 and 9.6% vs 18.5%; p 0.08).

Conclusion

PVI isolation using dedicated algorithms developed to guide the effectiveness of RFCA leads to a very high success-rate after a single procedure. The use of AI, which integrates contact force information with delivered power, reduces the procedural time and increases the overall success-rate

P1009Procedural success and long-term outcome of CTI ablation targeted with maximum voltage-guided approach: preliminary results from an Italian multicenter registry

Background

Ablation technique targeting high-amplitude signals (maximum voltage guided - MVG -) on the cavotricuspid isthmus (CTI) has emerged as viable alternative option compared to standard anatomical approach (ST) for the creation of bidirectional conduction block (BDB) across the isthmus but limited data are available to date.

Purpose

To evaluate the effectiveness of acute and long-term outcome of CTI ablation through MVG technique for AFL compared to standard linear (SL) lesion ablation.

Methods

Atrial Flutter Ablation in a Real World Population (LEONARDO) is a prospective, multicenter cohort study aimed at providing an estimate of acute to long-term outcome in a large population of patients (pts) indicated for AFL ablation. Recurrence of AFL were retrieved at 12-month follow-up. Complete BDB was defined by agreement with the presence of widely split double potentials (DP) along the ablation line and assessment of the atrial activation sequence (AAS). For MVG technique the ablation catheter was positioned at the site of maximum local electrogram voltage.

Results

Two-hundred fifteen consecutive pts were included (mean age 68 years, 73% male). A median of 4 [2–6] ablation lesions were required. Median follow up was 359 [192–443] days. Complete BDB was achieved in 175 (81.4%) pts (9 pts had DP only criterion, 30 pts had AAS only criterion whereas in 1 pt we failed to reach a BDB). In the 106 pts with complete data at 1-year follow-up, 10 (9.4%) had a recurrence of AFL. 171 pts (79%) underwent a SL ablation whereas 44 pts (21%) were treated by MVG approach. The median number of lesions/pt was significantly lower in the group of pts targeted with MVG compared to the SL approach (3 [2–4] vs 4 [2–8], p<0.01), whereas no differences were found in terms of fluoroscopy time (16 [12–18] min vs 12 [7–22] min, p=NS) or proportion of pts with BDB achievement (86.4% of the cases for MVG vs 80.1% of the cases for ST, p=NS). No complications were reported. AFL recurrence was comparable during follow-up between groups (8.3% for MVG vs 9.8% for SL ablation; p=NS).

Conclusion

Ablation of a targeted site through MGV approach seems to be safe and effective as standard anatomical ablation technique. This strategy may avoid unnecessary ablation of the entire anatomic isthmus.

Acknowledgement/Funding

None

P1037Relationship between left atrium low voltage areas and atrial fibrillation radiofrequency ablation success-rate: preliminary results of the SMOP study

Background

radio frequency catheter ablation (CA) is an effective therapy for atrial fibrillation (AF). Some authors have described a potential relationship between the presence of areas of fibrosis in the left atrium (LA) and the success of CA, nevertheless there is a lack of multicenter studies in this field.

Objective

the aim of our study was to assess the relationship between the of presence of low voltage areas of the LA detected during subtrate mapping at the time of the procedure and recurrences of AF after CA.

Methods

we analyzed 214 patients of the SMOP-AF (Substrate Mapping as Outcome Predictor in Atrial Fibrillation Ablation), a prospective multi-centric study enrolling patients with both paroxysmal and persistent AF undergoing a first radio-frequency CA procedure. High-density mapping was performed in sinus rhythm using the CARTO system before performing pulmonary vein isolation. Areas with less than 0,5 mV on mapping were defined as low voltage zone (LVZ), while between 0,5 mV and 1,5 mV intermediate voltage zone (IVZ). IVZ and LVZ were expressed as a percentage of the LA surface. Comparisons were made by Pearson correlation, cross-tables and Chi-square test or Student T test.

Results

the mean age of the enrolled population was 59±9 years, left ventricular ejection fraction was 59±9%, 86.4% of the pts had tested at least one anti-arrhythmic drug. Persistent atrial fibrillation was present in 10.3% of patients. The rate of documented AF recurrence at 3 months was 15,3% (n=29). There was a statistical significant correlation between the presence of IVZ and the rate of recurrences at 3 months (r=0.16, p value 0.03). Patients with IVZ greater than 4% of the left atrium surface showed a higher risk of recurrences (19.5% vs. 8,7%, p value 0.04). No statistical difference was observed in other procedural variables (number of lesions, contact force, force-time integral) among patients with or without recurrences.

Conclusion

Our study showed a relationship between CA short-term success rate and the presence of areas of intermediate voltage zone detected with high-density substrate mapping at the time of the procedure. The presence of areas of intermediate voltage zone greater than 4% of the LA determines a 2.5 folds increased risk of short-term recurrence. Our data needs to be confirmed in a longer follow-up.