Sinus rhythm endocardial mapping for channels identification in ischemic ventricular tachycardia using a modified electrophysiological triad

Background

In a previous study it was demonstrated that an electrophysiological triad was able to identify critical isthmus in atrial flutter (AFL) patients. This triad is based in the Carto® electroanatomical mapping (EAM) version 7, which displays a histogram of the local activation times (LAT) of the tachycardia cycle length (TCL), in addition to the activation and voltage maps.

Purpose

This study aimed to prospectively assess the ability of a modified electrophysiological triad to identify and localize the ventricular tachycardia's (VT) channels and entrance zones during sinus rhythm mapping.

Methods

Prospective analysis of a unicentric registry of individuals who underwent ischemic VT ablation with Carto® EAM, all in sinus rhythm. All patients with non-ischemic etiology, lack of high-density EAM or lack of mapping in any of the left ventricle walls or structures were excluded. Areas of late potentials and possible channels of re-entry were compared to a modified electrophysiological triad constituted by: areas of low-voltage (<0.5mV), a site of deep histogram valley (LAT-Valley) with less than 20% density points relative to the highest density zone and a prolonged LAT-Valley duration that included 10% or more of the total activation time mapped. We also assessed the relationship between the pre-valley bar (the LAT histogram bar immediately before the prolonged LAT-Valley) and the channel entrances.

Results

A total of 14 patients (14 men, median age 70 IQR 64–78 years) were included. All patients presented with ischemic VT and 86% had a previous inferior myocardial infarction. The median number of collected points were 1733 (IQR 1363–2729). All sinus rhythm maps presented with at least 1 LAT-Valley in the analysed histograms. All arrhythmias were effectively treated after undergoing radiofrequency in the LAT-Valley location, either by blocking the channel entrances or scar homogenization ablation strategy. Also, the pre-valley bar in the histogram marked all the channel entrances in the scar borders. No patient had relapse after a clinical follow up of over 6 months.

Conclusion

In a prospective analysis, a modified electrophysiological triad was able to identify the scar channels in sinus rhythm in all patients. The pre-valley bar in the histogram disclosed the channel entrances. Further studies are needed to assess the usefulness of this algorithm to simplify catheter ablation and improve clinical outcomes.

Funding Acknowledgement

Type of funding sources: None.

Evaluating the value of the timing of recurrence during blanking period after atrial fibrillation ablation

Introduction

In the first weeks after atrial fibrillation (AF) ablation, the arrythmia may recur theoretically due to transient local inflammation and not due to treatment failure. This is defined as the blanking period, with a proposed duration of 3 months. Recently, this time period has been brought into question. The aim of this work was to evaluate the correlation between the timing of blanking recurrence and late AF recurrence.

Methods

This was a single-centre retrospective study including patients without structural heart disease that underwent first AF ablation and were subsequently enrolled in the post ablation structured program between 2018 and 2021. Patients were excluded if they had <6 months follow-up. Appointment with ECG and Holter monitoring was performed at 1, 3, 6 and 12 months after ablation.

Results

We included a total of 193 patients (56% male, mean age 63±12 years). Of these, 79% had paroxysmal AF and mean left atrial volume index was 58±18 mL/m2. During the 3-month blanking period, there were 39 (21%) recurrences, 18 (9%) of which in the first month. After blanking period, at 6 months, 25 (13%) patients had AF recurrence, 56% of which had already recurred during blanking period. AF recurrence in the 2nd and 3rd month of blanking increased the odd of recurrence at 6-month by more than 5-fold (odds ratio (OR) 8,944; CI 95% 2,817–28,400, p<0.001 and OR 5,591; 95% CI 1,173–26,651; p=0.031). On the other hand, recurrence of AF during the 1st month of blanking was not associated with increased chance of 6-month AF recurrence (OR 2,095, 95% CI 0,630–6,964, p=0.227) (figure 1). There were no significant differences in clinical variables, including LA volume, between patients with 1-month recurrence and patients without recurrences. However, patients with AF recurrence in the 2nd and 3rd month of blanking had significantly increased LA volume.

Conclusion

Our study suggests that patients with AF recurrence in the 2nd and 3rd month of blanking have structurally different atria and are at a significantly higher risk of post blanking AF recurrence, in contrast with patients with AF recurrence in the 1st month of blanking, thus questioning the appropriate duration of the blanking period.

Funding Acknowledgement

Type of funding sources: None.

The peri-infarct gray zone of myocardial fibrosis is a better predictor of ventricular arrhythmias than dense core fibrosis in patients with previous myocardial infarction

Background

Current sudden cardiac death (SCD) risk stratification relies heavily on left ventricular ejection fraction (LVEF), but markers to refine risk assessment are needed. Dense core fibrosis (DCF) and peri-infarct “gray zone” of myocardial fibrosis (GZF) on late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) have been proposed as potential arrhythmogenic substrates. The aim of our study was to determine whether DCF and GZF could predict the occurrence of ventricular arrhythmias in patients with previous myocardial infarction.

Methods

We performed a single centre retrospective study enrolling consecutive patients with previous myocardial infarction undergoing CMR before implantable cardioverter-defibrillator (ICD) implantation. Areas of LGE were subdivided into “core” DCF and “peri-infarct” GZF zones based on signal intensity (>5 SD, and 2–5 SD above the mean of reference myocardium, respectively).

The primary endpoint was a composite of sudden arrhythmic death, appropriate ICD shock, ventricular fibrillation (VF), or sustained ventricular tachycardia (VT) as detected by the device.

Results

A total of 88 patients (median age 61 years [IQR 54–73], 84% male, median LVEF 30% [IQR 23–36%], 14% secondary prevention) were included. During a median follow-up of 23 months [IQR 9–38], 13 patients reached the primary endpoint (10 appropriate ICD shock, 2 sustained VT or VF, and 1 sudden arrhythmic death). Patients who attained the primary endpoint had similar DCF (30.4±14.7 g vs. 28.0±15.3 g; P=0.601) but a greater amount of GZF (18.1±9.6 g vs. 11.9±6.7 g; P=0.005). On univariate analysis, GZF was associated with the composite endpoint (HR: 1.09 per gram; 95% CI: 1.02–1.15; P=0.006), whereas DCF was not (HR: 1.01 per gram; 95% CI: 0.98–1.05; P=0.571). After adjustment for LVEF, GZF remained independently associated with the primary endpoint (adjusted HR: 1.06 per gram; 95% CI: 1.01–1.12; P=0.035). Decision tree analysis identified 11.9g of GZF as the best cut-off to predict life-threatening arrhythmic events. The primary endpoint occurred in 11 out of the 35 patients (31.4%) with GZF ≥11.9 g, but in only 2 of the 53 patients (3.8%) with GZF <11.9 g – Figure 1.

Conclusions

The extent of peri-infarct GZF seems to be a better predictor of ventricular arrhythmias than DCF. This parameter may be useful to identify a subgroup of patients with previous myocardial infarction at increased risk of life-threatening arrhythmic events.

Funding Acknowledgement

Type of funding sources: None.

Epidemiology and impact of frailty in patients with atrial fibrillation in Europe

BACKGROUND

Frailty is a medical syndrome characterised by reduced physiological reserve and increased vulnerability to stressors. Data regarding the relationship between frailty and atrial fibrillation (AF) are still inconsistent.

OBJECTIVES

We aim to perform a comprehensive evaluation of frailty in a large European cohort of AF patients.

METHODS

A 40-item frailty index (FI) was built according to the accumulation of deficits model in the AF patients enrolled in the ESC-EHRA EORP-AF General Long-Term Registry. Association of baseline characteristics, clinical management, quality of life, healthcare resources use and risk of outcomes with frailty was examined.

RESULTS

Among 10,177 patients [mean age (standard deviation) 69.0 (11.4) years, 4,103 (40.3%) females], 6,066 (59.6%) were pre-frail and 2,172 (21.3%) were frail, whereas only 1,939 (19.1%) were considered robust. Baseline thromboembolic and bleeding risks were independently associated with increasing FI. Frail patients with AF were less likely to be treated with oral anticoagulants (OACs) (odds ratio 0.70, 95% confidence interval 0.55-0.89), especially with non-vitamin K antagonist OACs and managed with a rhythm control strategy, compared with robust patients. Increasing frailty was associated with a higher risk for all outcomes examined, with a non-linear exponential relationship. The use of OAC was associated with a lower risk of outcomes, except in patients with very/extremely high frailty.

CONCLUSIONS

In this large cohort of AF patients, there was a high burden of frailty, influencing clinical management and risk of adverse outcomes. The clinical benefit of OAC is maintained in patients with high frailty, but not in very high/extremely frail ones.

Sinus rhythm endocardial mapping for channels identification in ischemic ventricular tachycardia using a modified electrophysiological triad

Funding Acknowledgements

Type of funding sources: None.

Background

In a previous study it was demonstrated that an electrophysiological triad was able to identify critical isthmus in atrial flutter (AFL) patients. This triad is based in the Carto® electroanatomical mapping (EAM) version 7, which displays a histogram of the local activation times (LAT) of the tachycardia cycle length (TCL), in addition to the activation and voltage maps.

Purpose

This study aimed to prospectively assess the ability of a modified electrophysiological triad to identify and localize the ventricular tachycardia’s (VT) channels and entrance zones during sinus rhythm mapping.

Methods

Prospective analysis of a unicentric registry of individuals who underwent ischemic VT ablation with Carto® EAM, all in sinus rhythm. All patients with non-ischemic etiology, lack of high-density EAM or lack of mapping in any of the left ventricle walls or structures were excluded. Areas of late potentials and possible channels of re-entry were compared to a modified electrophysiological triad constituted by: areas of low-voltage (<0.5mV), a site of deep histogram valley (LAT-Valley) with less than 20% density points relative to the highest density zone and a prolonged LAT-Valley duration that included 10% or more of the total activation time mapped. We also assessed the relationship between the pre-valley bar (the LAT histogram bar immediately before the prolonged LAT-Valley) and the channel entrances.

Results

A total of 14 patients (14 men, median age 70 IQR 64-78 years) were included. All patients presented with ischemic VT and 86% had a previous inferior myocardial infarction. The median number of collected points were 1733 (IQR 1363─2729). All sinus rhythm maps presented with at least 1 LAT-Valley in the analysed histograms. All arrhythmias were effectively treated after undergoing radiofrequency in the LAT-Valley location, either by blocking the channel entrances or scar homogenization ablation strategy. Also, the pre-valley bar in the histogram marked all the channel entrances in the scar borders. No patient had relapse after a clinical follow up of over 6 months.

Conclusion

In a prospective analysis, a modified electrophysiological triad was able to identify the scar channels in sinus rhythm in all patients. The pre-valley bar in the histogram disclosed the channel entrances. Further studies are needed to assess the usefulness of this algorithm to simplify catheter ablation and improve clinical outcomes.

Late gadolinium enhancement is a strong predictor of life threatening arrhythmias in patients with non-ischemic dilated cardiomyopathy undergoing ICD implantation for primary prevention of sudden card

Funding Acknowledgements

Type of funding sources: None.

Background

The usefulness of implantable cardioverter defibrillators (ICD) for primary prevention of arrhythmic sudden cardiac death (SCD) in patients with non-ischemic dilated cardiomyopathy (DCM) has been questioned. Efforts to improve risk stratification have included scores such as the ‘MADIT-ICD benefit score’, and the use of late gadolinium enhancement (LGE) in cardiac magnetic resonance (CMR).

The purpose of this study was to evaluate the potential usefulness of these two tools to assess the risk of life-threatening arrhythmias in patients with non-ischemic DCM undergoing ICD implantation for primary prevention of SCD.

Methods

We conducted a single-center retrospective study of consecutive patients who underwent contrast-enhanced CMR before ICD implantation for primary prevention of SCD. Patients with ischemic cardiomyopathy were used as reference. Patients with non-dilated cardiomyopathies were excluded.

The arrhythmic component of the MADIT-ICD benefit score (VT/VF score) was calculated for each patient, and considered high if ≥ 7, as recommended.

The primary endpoint was the occurrence of SCD or life-threatening arrhythmias (VF or VT >200 bpm). Follow-up was performed by device interrogation in all patients except those who suffered SCD.

Results

A total of 151 patients (93 ischemic, mean age 62±13 years, 75% male) with mean left ventricular ejection fraction (LVEF) of 27±8% were included. Overall, 72% (n=67) ischemic and 45% (n=26) non-ischemic patients had scores ≥ 7 and were considered high-risk. LGE was present in all patients with ischemic cardiomyopathy, and in 76% (n=44) of patients with non-ischemic DCM.

During a median follow-up of 21 (8-38) months, 21 patients (13.9%, 11 ischemic and 10 non-ischemic) met the primary endpoint.

Overall, the event-free survival of non-ischemic patients was similar to that of ischemic patients (log rank p=0.269) – Fig 1A. In patients with non-ischemic DCM, there were 7 arrhythmic events (26.9%) in those with MADIT-ICD VT/VF scores ≥7, and 3 events (9.4%) in those with scores <7 (log rank p= 0.104) – Fig 1B.

In the same population, there were 10 arrhythmic events (23%) in patients with LGE, but no events in patients without LGE (log rank p=0.036) – Fig 1C.

LVEF was similar in patients with and without arrhythmic events (26±8% vs. 27±7%, p=0.717), and in those with and without LGE (26±7% vs. 28±9%, p=0.342).

Conclusion

The presence of LGE is a strong predictor of life threatening arrhythmias in patients in non-ischemic DCM undergoing ICD implantation for primary prevention, seemingly outperforming the clinical MADIT-ICD benefit score.

The peri-infarct gray zone of myocardial fibrosis is a better predictor of ventricular arrhythmias than dense core fibrosis in patients with previous myocardial infarction

Funding Acknowledgements

Type of funding sources: None.

Background

Current sudden cardiac death (SCD) risk stratification relies heavily on left ventricular ejection fraction (LVEF), but markers to refine risk assessment are needed. Dense core fibrosis (DCF) and peri-infarct "gray zone" of myocardial fibrosis (GZF) on late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) have been proposed as potential arrhythmogenic substrates. The aim of our study was to determine whether DCF and GZF could predict the occurrence of ventricular arrhythmias in patients with previous myocardial infarction.

Methods

We performed a single centre retrospective study enrolling consecutive patients with previous myocardial infarction undergoing CMR before implantable cardioverter-defibrillator (ICD) implantation. Areas of LGE were subdivided into "core" DCF and "peri-infarct" GZF zones based on signal intensity (>5 SD, and 2-5 SD above the mean of reference myocardium, respectively).

The primary endpoint was a composite of sudden arrhythmic death, appropriate ICD shock, ventricular fibrillation (VF), or sustained ventricular tachycardia (VT) as detected by the device.

Results

A total of 88 patients (median age 61 years [IQR 54-73], 84% male, median LVEF 30% [IQR 23-36%], 14% secondary prevention) were included. During a median follow-up of 23 months [IQR 9-38], 13 patients reached the primary endpoint (10 appropriate ICD shock, 2 sustained VT or VF, and 1 sudden arrhythmic death). Patients who attained the primary endpoint had similar DCF (30.4g ± 14.7 vs. 28.0g ± 15.3; P = 0.601) but a greater amount of GZF (18.1g ± 9.6 vs. 11.9g ± 6.7; P = 0.005). On univariate analysis, GZF was associated with the composite endpoint (HR: 1.09 per gram; 95%CI: 1.02-1.15; P = 0.006), whereas DCF was not (HR: 1.01 per gram; 95%CI: 0.98-1.05; P = 0.571). After adjustment for LVEF, GZF remained independently associated with the primary endpoint (adjusted HR: 1.06 per gram; 95% CI: 1.01-1.12; P = 0.035). Decision tree analysis identified 11.9g of GZF as the best cut-off to predict life-threatening arrhythmic events. The primary endpoint occurred in 11 out of the 35 patients (31.4%) with GZF ≥11.9g, but in only 2 of the 53 patients (3.8%) with GZF <11.9g – Figure.

Conclusions

The extent of peri-infarct GZF seems to be a better predictor of ventricular arrhythmias than DCF. This parameter may be useful to identify a subgroup of patients with previous myocardial infarction at increased risk of life-threatening arrhythmic events.

Relationship between electrical activity and left atrial volume during atrial fibrillation

Funding Acknowledgements

Type of funding sources: None.

Introduction

Pulmonary veins (PV) ostia were previously identified as the left atrium (LA) areas with the shortest refractory period during sinus rhythm. Pulmonary veins isolation (PVI) became standard of care, but clinical results are still suboptimal. Currently, atrial fibrillation (AF) cycle length mapping (CLM) is possible due to a special tool of the Carto® electroanatomical mapping, which identifies areas in the left atria with shortest refractory period, during AF.

Purpose

Using this new EAM feature, our study aimed to assess the relationship between short refractory period LA areas and left atrial volume and AF type, known predictors of AF relapse.

Methods

Retrospective analysis of an unicentric registry of individuals with symptomatic drug-refractory AF who underwent PVI AF ablation with Carto® EAM. CLM was performed. CL maps were created with a high-density mapping Pentaray® catheter before and after PVI. We assessed areas of short cycle length (SCL) (defined as 120 to 250ms), and their relationships with complex fractionated atrial electrograms (CFAE), and low-voltage zones (from 0.1 to 0.3mV).

Results

A total of 35 patients (21 men, median age 62 IQR 53-71 years) were included. Most patients presented with persistent AF (n=23, 66%), and 8 patients (23%) had a previous PVI. The mean shortest measured cycle length in AF was 134ms (SD ± 23ms). There was a negative correlation between LA volume and SCL areas after PVI (Spearman Correlation coefficient [ρ] = - 0.47, P = 0.037). There was no correlation between LA volume and SCL areas before the PVI procedure (ρ = -0.06, P = 0.776), nor between AF type and SCL (ρ = -0.118, P = 0.620). All patients presented areas of SCL located in the PVs or their insertion, 76% in the posterior/roof region adjacent to the left superior pulmonary vein (LSPV) and 76% in the anterior region of the wall adjacent to the right superior pulmonary vein (RSPV). These two areas remained the fastest even after PVI. The anterior mitral region rarely presented SCL (16%). SCL were related to low-voltage areas in 93% and were adjacent to CFAE in 84% of the cases. Low-voltage areas and CFAE were more frequent and had a larger LA dispersion than SCL.

Conclusion

Our study shows that LA volume, not AF type, is correlated with remaining SCL areas after a pulmonary vein isolation procedure. This finding suggests a possible causal link between increased LA volume and AF relapse post-PVI. More studies are needed to assess the role of the SCL areas as a potential ablation target and their impact on AF ablation outcomes.

Ventricular tachycardia ablation in nonischemic cardiomyopathy

Introduction

Catheter ablation outcomes for drug-resistant ventricular tachycardia (VT) in nonischemic cardiomyopathy (NICM) are suboptimal when compared to ischemic cardiomyopathy. We aimed to analyse the long-term efficacy and safety of percutaneous catheter ablation in this subset of patients.

Methods

Single-center observational retrospective registry including consecutive NICM patients who underwent catheter ablation for drug-resistant VT during a 10-year period. The efficacy endpoint was defined as VT-free survival after catheter ablation, while safety outcomes were defined by 30-days mortality and procedure-related complications. Independent predictors of VT recurrence were assessed by Cox regression.

Results

In a population of 68 patients, most were male (85%), mean left ventricular ejection fraction (LVEF) was 34±12%, and mean age was 58±15 years. All patients had an implantable cardioverter-defibrillator. Twenty-six (38%) patients underwent epicardial ablation (table 1). Over a median follow-up of 3 years (IQR 1–8), 41% (n=31) patients had VT recurrence and 28% died (n=19). Multivariate survival analysis identified LVEF (HR= 0.98; 95% CI 0.92–0.99, p=0.046) and VT storm at presentation (HR=2.38; 95% CI 1.04–5.46, p=0.041) as independent predictors of VT recurrence. The yearly rates of VT recurrence and overall mortality were 21%/year and 10%/year, respectively. No patients died at 30-days post-procedure, and mean hospital length of stay was 5±6 days. The complication rate was 7% (n=5, table 1), mostly in patients undergoing epicardial ablation (4 vs 1 in endocardial ablation, P=0.046).

Conclusion

LVEF and VT storm at presentation were independent predictors of VT recurrence in NICM patients after catheter ablation. While clinical outcomes can be improved with further technical and scientific development, a tailored endocardial/epicardial approach was safe, with low overall number of complications and no 30-days mortality.

Funding Acknowledgement

Type of funding sources: None.

A new electrophysiological triad for atrial flutter critical isthmus identification and localization

Introduction

In a previous retrospective study it was demonstrated that an electrophysiological triad was able to identify critical isthmus in atrial flutter (AFL) patients. This triad is based in the Carto® electroanatomical mapping (EAM) version 7, which displays a histogram of the local activation times (LAT) of the tachycardia cycle length (TCL), in addition to the activation and voltage maps. This study aimed to prospectively assess the ability of an electrophysiological triad to identify and localize the AFL's critical isthmus.

Methods

Prospective analysis of a unicentric registry of individuals who underwent left AFL ablation with Carto® EAM. All patients with non-left AFL, lack of high-density EAM, less than 2000 collected points or lack of mapping in any of the left atrium walls or structures were excluded. Ablation sites of arrhythmia termination were compared to an electrophysiological triad constituted by: areas of low-voltage (0.05 to 0.3mV), sites of deep histogram valleys (LAT-Valleys) with less than 20% density points relative to the highest density zone and a prolonged LAT-Valley duration that included 10% or more of the TCL. The longest LAT-Valley was designated as the primary valley, while additional valleys were named as secondary.

Results

A total of 12 patients (9 men, median age 72 IQR 67–75 years) were included. All patients presented with left AFL and 67% had a previous atrial fibrillation and/or flutter ablation. The median TCL and number collected points were 250 (230–290) milliseconds and 3150 (IQR 2340–3870) points, respectively. All AFL presented with at least 1 LAT-Valley in the analysed histograms, which corresponded to heterogeneous low-voltage areas (0.05 to 0.3mV) and encompassed more than 10% of TCL. Eleven of the 12 patients presented with at least 1 secondary LAT-Valley. All arrhythmias were effectively terminated after undergoing radiofrequency ablation in the primary or the secondary LAT-Valley location.

Conclusion

In a prospective analysis, an electrophysiological triad was able to identify the AFL critical isthmus in all patients. Further studies are needed to assess the usefulness of this algorithm to improve catheter ablation outcomes.

Funding Acknowledgement

Type of funding sources: None.

Electrical anatomy of the left atrium during atrial fibrillation

Introduction

Twenty years ago, pulmonary veins (PV) ostia were identified as the left atrium (LA) areas with the shortest refractory period during sinus rhythm. Pulmonary veins isolation (PVI) became standard of care, but clinical results are still suboptimal. Today, a special tool using the Carto® electroanatomical mapping (EAM) allows for AF cycle length mapping (CLM), to identify the areas in the left atria with shortest refractory period, during atrial fibrillation. Using this EAM tool, our study aimed to find the LA areas with the shortest refractory period to better recognize electrical targets for catheter ablation.

Methods

Retrospective analysis of an unicentric registry of individuals with symptomatic drug-refractory AF who underwent PVI with Carto® EAM. CLM was performed with a high-density mapping Pentaray® catheter before and after PVI and in 4 redo procedures. We assessed areas of short cycle length (SCL) (defined as 120 to 250ms), and their relationships with complex fractionated atrial electrograms (CFAE), and low-voltage zones (from 0.1 to 0.3mV).

Results

A total of 18 patients (8 men, median age 63 IQR 58–71 years) were included. Most patients presented with persistent AF (n=12, 67%), and 4 patients (22%) had a previous PVI. The mean shortest measured cycle length in AF was 140ms (SD ±27ms). All patients presented areas of SCL located in the PVs or their insertion, 70% in the posterior/roof region adjacent to the left superior pulmonary vein (LSPV) (figure 1) and 60% in the anterior region of the right superior pulmonary vein (RSPV). These two areas remained the fastest even after PVI. The anterior mitral region rarely presented SCL (17%). SCL were related to low-voltage areas in 94% and were adjacent to CFAE. Low-voltage areas and CFAE were more frequent and had a larger LA dispersion than SCL.

Conclusion

We confirmed in 3D mapping that PVs are the LA zones with shortest refractory period, not only in sinus rhythm but also during AF. The persistence of SCL areas in the border zones of the PVI lines suggest the benefit of a more extensive CLM guided ablation. Larger studies are needed.

Funding Acknowledgement

Type of funding sources: None. Short cycle length mapping

Prognostic impact of subcutaneous implantable cardioverter-defibrillator appropriate and inappropriate shocks

Funding Acknowledgements

Type of funding sources: None.

Background

Previous studies have shown an adverse prognosis for patients with transvenous implantable cardioverter-defibrillators (ICD) who receive both appropriate and inappropriate shocks. There is a paucity of data regarding the prognosis of inappropriate shocks in patients with a subcutaneous ICD (S-ICD).

Purpose

To assess and characterize S-ICD appropriate (AS) and inappropriate shocks (IAS) and their impact on mortality.

Methods

Single center observational registry of 162 consecutive patients who underwent S-ICD implantation for primary and secondary prevention between November 2009 and September 2020. Only follow-up data of at least 6 months was analysed to identify predictors of both IAS and AS and their mortality impact.

Results

A total of 144 patients were included in the analysis. Mean age was 42.2 ± 16.6 years and 75% of the patients were male. One hundred and four patients (72.2%) implanted the S-ICD in primary prevention. The most common etiology was ischemic cardiomyopathy (22.9%) followed by hypertrophic cardiomyopathy (18.8%) and dilated idiopathic cardiomyopathy (14.6%). During a mean follow-up of 42.3 ± 29.9 months a total of 48 patients (33.3%) experienced at least one S-ICD shock. Twenty-nine (20.1%) patients received AS due to VT/VF and 31 patients (21.5%) received IAS. Eighteen (58.1%) of the IAS were due to oversensing/noise/discrimination errors and the remaining due to supraventricular tachycardia. Overall, patients with AS (HR 4.93, 95% CI 1.58-15.36, p = 0.006) and higher number of total AS (HR 1.10, 95% CI 1.00-1.20, p = 0.044) were associated with higher mortality during follow-up. S-ICD IAS therapy did not affect overall mortality (HR 1.71, 95% CI 0.21-14.0, p = 0.616). Conclusions: In patients with S-ICD, those who receive AS, in contrast to IAS, seem to have a worse prognosis. Large scale studies are needed to confirm this hypothesis and to explain this findings. Abstract Figure. Survival curves for AS and IAS

Electrical anatomy of the left atrium during atrial fibrillation

Funding Acknowledgements

Type of funding sources: None.

Introduction

Twenty years ago, pulmonary veins (PV) ostia were identified as the left atrium (LA) areas with the shortest refractory period during sinus rhythm. Pulmonary veins isolation (PVI) became standard of care, but clinical results are still suboptimal. Today, a special tool using the Carto® electroanatomical mapping (EAM) allows for AF cycle length mapping (CLM), to identify the areas in the left atria with shortest refractory period, during atrial fibrillation. Using this EAM tool, our study aimed to find the LA areas with the shortest refractory period to better recognize electrical targets for catheter ablation.

Methods

Retrospective analysis of an unicentric registry of individuals with symptomatic drug-refractory AF who underwent PVI with Carto® EAM. CLM was performed with a high-density mapping Pentaray® catheter before and after PVI and in 4 redo procedures. We assessed areas of short cycle length (SCL) (defined as 120 to 250ms), and their relationships with complex fractionated atrial electrograms (CFAE), and low-voltage zones (from 0.1 to 0.3mV).

Results

A total of 18 patients (8 men, median age 63 IQR 58-71 years) were included. Most patients presented with persistent AF (n = 12, 67%), and 4 patients (22%) had a previous PVI. The mean shortest measured cycle length in AF was 140ms (SD ±27ms). All patients presented areas of SCL located in the PVs or their insertion, 70% in the posterior/roof region adjacent to the left superior pulmonary vein (LSPV) (figure 1) and 60% in the anterior region of the right superior pulmonary vein (RSPV). These two areas remained the fastest even after PVI. The anterior mitral region rarely presented SCL (17%). SCL were related to low-voltage areas in 94% and were adjacent to CFAE. Low-voltage areas and CFAE were more frequent and had a larger LA dispersion than SCL.

Conclusion

  We confirmed in 3D mapping that PVs are the LA zones with shortest refractory period, not only in sinus rhythm but also during AF. The persistence of SCL areas in the border zones of the PVI lines suggest the benefit of a more extensive CLM guided ablation. Larger studies are needed. Abstract Figure 1

Ventricular tachycardia ablation in nonischemic cardiomyopathy

Funding Acknowledgements

Type of funding sources: None.

INTRODUCTION

Catheter ablation outcomes for drug-resistant ventricular tachycardia (VT) in nonischemic cardiomyopathy (NICM) are suboptimal when compared to ischemic cardiomyopathy. We aimed to analyse the long-term efficacy and safety of percutaneous catheter ablation in this subset of patients.

METHODS

Single-center observational retrospective registry including consecutive NICM patients who underwent catheter ablation for drug-resistant VT during a 10-year period. The efficacy endpoint was defined as VT-free survival after catheter ablation, while safety outcomes were defined by 30-days mortality and procedure-related complications. Independent predictors of VT recurrence were assessed by Cox regression.

RESULTS

In a population of 68 patients, most were male (85%), mean left ventricular ejection fraction (LVEF) was 34 ± 12%, and mean age was 58 ± 15 years. All patients had an implantable cardioverter-defibrillator. Twenty-six (38%) patients underwent epicardial ablation (table 1). Over a median follow-up of 3 years (IQR 1-8), 41% (n = 31) patients had VT recurrence and 28% died (n = 19). Multivariate survival analysis identified LVEF (HR= 0.98; 95%CI 0.92-0.99, p = 0.046) and VT storm at presentation (HR = 2.38; 95%CI 1.04-5.46, p = 0.041) as independent predictors of VT recurrence. The yearly rates of VT recurrence and overall mortality were 21%/year and 10%/year, respectively. No patients died at 30-days post-procedure, and mean hospital length of stay was 5 ± 6 days. The complication rate was 7% (n = 5, table 1), mostly in patients undergoing epicardial ablation (4 vs 1 in endocardial ablation, P = 0.046).

CONCLUSION

LVEF and VT storm at presentation were independent predictors of VT recurrence in NICM patients after catheter ablation. While clinical outcomes can be improved with further technical and scientific development, a tailored endocardial/epicardial approach was safe, with low overall number of complications and no 30-days mortality. Abstract Figure.

Assessment of wavefront propagation speed on the right ventricular outflow tract: deceleration zones associated with the presence of low voltage areas

Funding Acknowledgements

Type of funding sources: None.

Background and aims

Activation wavefront is rapid and uniform in normal myocardium. Fibrosis is associated with deceleration zones (DZ) and late activated zones. The presence of low voltage areas (LVAs) in the right ventricular outflow tract (RVOT) of patients with premature ventricular contractions (PVCs) from this origin has been described previously. The aim of this study was to evaluate in sinus rhythm, the RVOT endocardial activation duration (EAD) and the presence of DZs, in patients with PVCs and in controls.

Methods

Consecutive patients with frequent (>10.000/24 h) idiopathic PVCs with inferior axis subjected to ablation that had an activation and voltage map of the RVOT performed in sinus rhythm. A control group of patients without PVCs that underwent ablation of supraventricular arrhythmias was also studied. Patients with structural heart disease, previous ablation or conduction disease were excluded. The RVOT EAD was measured as the time interval between the earliest and the latest activated region. Also evaluated the number of 10 ms isochrones throughout the RVOT and the maximal number of 10 ms isochrones within 1 cm, and a DZ was defined as a zone with > 3 isochrones within 1 cm. Low voltage areas (LVA) were defined as areas with local electrogram amplitude <1.5 mV.

Results

42 patients, 29 in the PVC group and 13 control subjects. The site of origin of the PVCs was the RVOT in 23 patients and the LVOT in 6. The characteristics of the two groups are displayed in the Table. Patients with PVCS had longer RVOT EAD, total number of isochrones and presence of DZ was also significantly higher (See table).  LVAs were more frequent in PVCs from the RVOT than from the LVOT (83% vs 33%, p = 0.033). Patients with LVA had longer EAD 60 (52-67) vs 36 (34-40) ms, p < 0.0001 (Figure A) and more DZ than patients without LVA 95% vs 0%, p < 0.0001 (Figure B and C).

Conclusions

The velocity of the wavefront propagation was slower and DZs were more frequently present in patients with PVCs and were associated with presence of LVAs. All sampleN= 42PVCsN = 29ControlsN = 13p-valueAge in years, median (Q1-Q3)56 (35-65)58 (38-66)53 (28-67)0.648Male gender, n (%)19 (45)14 (48)5 (39)0.401Nº points in the map, median (Q1-Q3)410 (338-589)467 (345-660)345 (333-465)0.056Activation duration in ms, median (Q1-Q3)41.8 (36-61)56 (41-66)39 (35-41)0.001Nº isochrones, median (Q1-Q3)4 (4-6)5 (4-6)4 (4-4)0.037Presence of DZs, n (%)20 (48)20 (69)0 (0)<0.0001Presence of LVAs, n(%)21 (50)21 (72)0 (0)<0.0001Abstract Figure.

A new electrophysiological triad for atrial flutter critical isthmus identification and localization

Funding Acknowledgements

Type of funding sources: None.

Introduction

In a previous retrospective study it was demonstrated that an electrophysiological triad was able to identify critical isthmus in atrial flutter (AFL) patients.  This triad is based in the Carto® electroanatomical mapping (EAM) version 7, which displays a histogram of the local activation times (LAT) of the tachycardia cycle length (TCL), in addition to the activation and voltage maps. This study aimed to prospectively assess the ability of an electrophysiological triad to identify and localize the AFL’s critical isthmus.

Methods

Prospective analysis of a unicentric registry of individuals who underwent left AFL ablation with Carto® EAM. All patients with non-left AFL, lack of high-density EAM, less than 2000 collected points or lack of mapping in any of the left atrium walls or structures were excluded. Ablation sites of arrhythmia termination were compared to an electrophysiological triad constituted by: areas of low-voltage (0.05 to 0.3mV), sites of deep histogram valleys (LAT-Valleys) with less than 20% density points relative to the highest density zone and a prolonged LAT-Valley duration that included 10% or more of the TCL. The longest LAT-Valley was designated as the primary valley, while additional valleys were named as secondary.

Results

A total of 12 patients (9 men, median age 72 IQR 67-75 years) were included. All patients presented with left AFL and 67% had a previous atrial fibrillation and/or flutter ablation. The median TCL and number collected points were 250 (230─290) milliseconds and 3150 (IQR 2340─3870) points, respectively. All AFL presented with at least 1 LAT-Valley in the analysed histograms, which corresponded to heterogeneous low-voltage areas (0.05 to 0.3mV) and encompassed more than 10% of TCL. Eleven of the 12 patients presented with at least 1 secondary LAT-Valley. All arrhythmias were effectively terminated after undergoing radiofrequency ablation in the primary or the secondary LAT-Valley location.

Conclusion

In a prospective analysis, an electrophysiological triad was able to identify the AFL critical isthmus in all patients. Further studies are needed to assess the usefulness of this algorithm to improve catheter ablation outcomes.

Age influence on the lipolytic effect of glucagon in geese

The lipolytic effect of glucagon was measured in vitro with adipose tissue of "young" (4-8 wk) and "old" (over 1 yr) geese. The response of the young geese tissue was about twice that observed with tissue of old geese, for glucagon concentrations of 0.05, 0.5, and 5.0 mug/ml. Our estimates indicate that the number of adipose cells per g of adipose tissue of young geese was three times that of the old geese tissue. This suggests that the greater lipolytic response to glucagon, observed in young geese adipose tissue, may possibly be due to its greater cellularity, rather than to a greater lipolytic response of the individual adipocyte. The lipolytic effect of glucagon in vivo, for each of the doses between 1.0 and 20.0 mug/kg, was significantly greater in the old than in the young geese. The slope of the linear equation relating log10 of glucagon dose and elevation of plasma FFA 5 min after injection, was significantly greater for the old than for the young geese. In the goose, therefore, the influence of age on the adipokinetic effect of glucagon appears to be mediated by factors operating in the whole animal, more than by changes in the adipose cell itself. A slower removal rate of circulating FFA by the old geese, could be one of these factors.