Factors predicting repeated ablation in ventricular tachycardia patients

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Heart Program

Background

Catheter ablation has emerged to be the principal treatment for recurrent ventricular tachycardia (VT). Previously, several predictors of VT recurrence have been described, such as LVESD, severe MR, incessant VT, ICD shocks and elevated LDH levels. However, factors predicting an additional ablation are unknown.

Purpose

We aimed to establish predictors of repeat ablation and compare to the predictors of ventricular arrhythmia recurrence during 1-year follow-up in structural heart disease.

Methods

Baseline medical history, laboratory results, imaging parameters, clinical properties of VTs, and procedural data were gathered in a structured database.

Results

Out of the 272 patients, 96 (35%) experienced recurrence and 36 (13%) had repeated procedures within 1 year. Independent predictors of recurrence were left ventricular end systolic diameter (HR = 1.516, p=0.015), severe mitral regurgitation (HR = 2.446, p = 0.002), incessant VT (HR = 1.64, p = 0.02), VT inducibility (HR = 3.71, p = 0.003), ICD shocks (HR = 1.95, p = 0.002) and elevated LDH levels (HR = 1.26, p = 0.003). Regarding redo ablation, elevated LDH level (HR = 1.64, p = 0.01), incessant VT (HR = 2.94, p < 0.001), ICD shocks (HR = 2.38, p = 0.02), only exit point ablation (HR = 2.14, p = 0.023) were independent predictors, while hypertension (HR = 0.32, p = 0.03), longer transmitral E-wave deceleration time (HR = 0.47, p = 0.04), substrate modification (HR = 0.47, p = 0.044) were protective.

Conclusion

Predictors of repeat ablation overlap only partially with those of VT recurrence. Predictors implying higher risk VT episodes predict both recurrence and repeat ablation while factors associated with more severe left ventricular systolic dysfunction predict recurrence but not a redo procedure.

Abutting left atrial appendage and left superior pulmonary vein predicts recurrence of atrial fibrillation after point-by-point pulmonary vein isolation

Funding Acknowledgements

Type of funding sources: None.

Background

Catheter ablation is the cornerstone for rhythm control in patients with drug-refractory atrial fibrillation (AF). Baseline predictors of AF recurrence after catheter ablation are well established, such as female gender and left atrial enlargement. The role of the spatial relationship between the left superior pulmonary vein (LSPV) and left atrial appendage (LAA) is unknown.

Purpose

We sought to evaluate whether juxtaposed LSPV and LAA plays a role in AF recurrence after catheter ablation for paroxysmal AF.

Methods

Consecutive patients, who underwent point-by-point radiofrequency catheter ablation for paroxysmal AF at our hospital between January of 2014 and December of 2017, were enrolled in the study. All patients underwent pre-procedural cardiac CT-angiography (CTA) for the assessment of left atrial (LA) and pulmonary vein (PV) anatomy. Abutting LAA-LSPV was defined as cases when LSPV touched the posterior aspect of LAA (distance less than 2 mm).

Results

We included 428 patients (60.7 ± 10.8 years, 35.5% female). AF recurrence rate was 33.4% with a median recurrence-free time of 21.2 (IQR = 8.8-43.0) months. In the univariate analysis, female sex (HR = 1.45; 95%CI = 1.04-2.01; p = 0.028), LA volume (HR = 1.01; 95%CI = 1.00-1.01; p = 0.042), and cases when LSPV touched the posterior wall of LAA (HR = 1.53; 95%CI = 1.09-2.14; p = 0.013) were associated with AF recurrence. In the multivariate analysis, female sex (adjusted HR = 1.55; 95%CI = 1.06-2.28; p = 0.024), LA volume (adjusted HR = 1.01; 95%CI = 1.00-1.02; p = 0.028), and abutting LAA-LSPV (adjusted HR = 1.60; 95%CI = 1.13-2.50; p = 0.008) remained significant predictors of AF recurrence.

Conclusion

Female gender, higher LA volume, and abutting LSPV and LAA predispose patients to have a higher chance for arrhythmia recurrence after catheter ablation for paroxysmal AF.

P333Left atrial function by echocardiography is independent of degree of left atrial electrical scar

Introduction

Assessment of left atrial function via transthoracic echocardiography (TTE) is performed most commonly by measuring the transmitral A wave in sinus rhythm. Left atrial (LA) fibrosis plays an important role in the pathogenesis and perpetuation of Atrial Fibrillation (AF). It may be identified by bipolar voltage (BiV) mapping, which can easily be performed at the beginning of a Pulmonary Vein Isolation (PVI) procedure. The relationship between the degree of LA fibrosis, characterised with mapping, and LA function, determined by echocardiography, has not previously been elucidated.

Methods

Patients were enrolled in a project to evaluate the degree of fibrosis during PVI procedures. Pre-procedure TTEs of those presenting in sinus rhythm were assessed and the transmitral A wave was measured and compared to the degree of scarring seen. The high density electroanatomic maps (HD-EAMs) created during the PVIs were analysed using a novel VHA algorithm after the procedure. All points with voltages < 0.5mV were defined to have electrical scar. Patients were classified into 4 quartiles based on the levels of scar seen (Figure 1).

Results

39 patients were included in the evaluation. Average age was 60.6 +/- 13.2 years. 32 (82.0%) of the patients were male. Mean CHADS2VASc score was 1.5. The mean percentage of scar was calculated as 19.6 +/- 15.9%. The average A wave was 0.62 +/- 0.18 ms-1. Pearson’s correlation coefficient showed no relationship between LA scar and either A wave velocities (r = 0.26, p = 0.11) or E:A ratio (r=-0.02, p = 0.91). A significant correlation between A wave velocity and CHADS2VASc was observed (r = 0.49, p = 0.001).

Conclusion

Our study demonstrates no relationship between degree of LA scarring and reduced LA function on TTE as assessed by the A wave. It has been established that structural remodelling in AF (such as atrial dilatation) may occur independently of the electrical remodelling. A potential explanation for our findings is that the electrical scarring in AF, which results in alterations in refractory periods, precedes the negative remodelling which ultimately results in reduced atrial function. This hypothesis would need to be further evaluated in larger studies.

Abstract Figure 1

P956Improved quality of life and symptomatic atrial fibrillation reduction in patients treated with a standardized ablation index workflow

Background/Introduction

The use of a standardized ‘CLOSE’ ablation workflow for pulmonary vein isolation (PVI), with defined inter-tag distance (ITD) with targeted ablation index (AI) values, has been shown in single centre reports to result in good outcomes. The effect of this approach on patients’ quality of life (QoL) has not been studied.

Purpose

To evaluate the effects of paroxysmal atrial fibrillation (PAF) ablation by the CLOSE workflow on QoL and symptomatic AF reduction in the multicenter VISTAX study.

Methods

329 patients with PAF (61.5% male, 61.3 ± 10.1 year) were treated at 17 European centres by point-by-point radiofrequency ablation using the CLOSE protocol to achieve PVI.  An ITD ≤6mm and AI values of ≥400 on the posterior wall and ≥550 on the anterior wall were targeted. The AI value on the posterior wall was lowered as per investigator discretion in case of safety concerns. Patients were monitored for atrial arrhythmia recurrences via weekly and symptom-activated transtelephonic monitoring (TTM), for 12 months post procedure. Patients completed an Atrial Fibrillation Effect on Quality-of-life (AFEQT) questionnaire at their baseline and 12-month follow up visits.

Results

Majority (83.3% [274/329]) of patients experienced freedom from symptomatic atrial recurrence through 12 months. Of the 70 documented recurrences, 34 (49%) were documented by trans-telephonic monitoring only. All domains captured on the AFEQT questionnaire showed improvement with the overall score improving by 25.7, which exceeded the threshold of clinically meaningful improvement (±5) (Table). Patient reported most improvements in PAF control and symptoms relieved. The overall AFEQT score improvement was seen both in patients with or without documented atrial arrhythmia recurrence, with improvement by 21.5 and 26.8, respectively.

Conclusion

PAF ablation using a standardized CLOSE workflow resulted in consistent improvements in QoL. The improved QoL was observed regardless of atrial arrhythmia recurrence likely reflecting the low residual arrhythmia burden in patients with documented recurrence identified only on TTM.

AFEQT Scores Through 12 Months AFEQT Domain Baseline 12 Months Change from Baseline* Daily Activities 59.2 85.3 26.0 Treatment Concerns 62.2 88.1 26.0 Controlling PAF 50.2 87.8 37.5 Symptoms 63.7 89.0 25.1 Symptoms Relieved 52.0 88.4 36.3 Overall AFEQT Score 61.3 87.2 25.7 *only includes patients who completed both baseline and 12 month AFEQT questionnaire

1242The flexibility, ease of using, and leaving curve of a standardized ablation index workflow for catheter ablation of paroxysmal atrial fibrillation

Background/Introduction

The ‘CLOSE’ protocol, incorporating standardized ablation index (AI) targets in conjunction with defined inter-tag distance (ITD) has been shown to improve the acute and long-term success of pulmonary vein isolation (PVI) when treating paroxysmal atrial fibrillation (PAF). The reproducibility and learning curve for this protocol has not been studied.

Purpose

To assess the acute and long-term efficacy of CLOSE PVI across multiple operators (n = 37) in the 17-centre European study ‘VISTAX’.

Methods

329 patients with PAF (61.8% male, 61.3 ± 10.1 years) underwent PVI according to the CLOSE protocol, with target AI values for each lesion of ≥400 on the posterior wall and ≥550 on the anterior wall, and target ITD of ≤6mm. Each 3-dimensional electroanatomic map was evaluated at a core lab where adherence to each of these criteria was assessed. 281/329 patients (85.1%) fulfilled all standardized workflow requirements and were adjudicated as having their PVI per-protocol (PP). First pass PVI and acute effectiveness (adenosine-proof first pass PVI at 30-minute challenge) were recorded. Clinical effectiveness was assessed as freedom from atrial arrhythmia recurrence through 12 months recorded via transtelephonic monitoring (weekly and symptomatically), in addition to holter and electrocardiogram monitoring during 3,6,12 month follow up visits. Learning curve analysis was evaluated on all investigators.

Results

First pass PVI rates were similar in the overall (86%) and PP cohorts (85%), as was acute effectiveness (82% in both cohorts). Freedom from atrial arrhythmia at 12 months too was identical for both cohorts (79%). Total procedure time and total ablation time decreased by an average 8 minutes and 10 minutes respectively after the first procedure and then showed further steady decreases over the number of ablations performed by the investigator (Figure).  The procedural efficiencies and clinical success were reproducible across different centers. No significant deviations were found from individual sites.

Conclusion

The standardized CLOSE workflow is reproducible across centres, and is ‘forgiving’ without impacting on high efficacy of almost 80%. The learning curve is short, suggesting that the excellent clinical results can be replicated widely and easily.

Abstract Figure. Learning Curves- Procedure & Ablation

5107Survival prediction in patients undergoing cardiac resynchronization therapy: a machine learning based risk stratification system

Background

Cardiac Resynchronization Therapy (CRT) has well-known beneficial effects in patients with advanced heart failure, reduced ejection fraction and wide QRS complex. However, mortality rates still remain high in this patient population. Therefore, precise risk stratification would be essential, nonetheless, the currently available risk scores have several shortcomings which hamper their utilization in the everyday clinical practice.

Purpose

Accordingly, our objective was to design and validate a machine learning based risk stratification system to predict 2-year and 5-year mortality from pre-implant parameters of patients undergoing CRT implantation.

Methods

We trained two models separately to predict 2-year (model 1) and 5-year mortality (model 2). As training cohort of model 1 we used 1678 patients (67±10 years, 1251 [75%] males) undergoing CRT implantation. From this population, 1320 patients (66±10 years, 1005 [76%] males) also completed 5-year follow-up and they served as the training cohort for model 2. Forty-seven pre-implant parameters (demographics, cardiovascular risk factors and clinical characteristics) were used to train the models. Our models were designed in a way to tolerate missing values. Among non-linear classifiers, random forest demonstrated the best performance. We validated our models, along with the Seattle Heart Failure Model (SHFM), VALID-CRT risk score and EAARN score on an independent cohort of 136 patients (66±10 years, 110 [81%] males). Based on the predicted probability of survival, patients were split into quartiles and survival was plotted via Kaplan-Meier (KM) curves.

Results

There were 358 (21%) deaths in the 2-year, 697 (53%) deaths in the 5-year training cohort. In the validation cohort, there were 30 (22%) deaths at 2 years and 58 (43%) deaths at 5 years after CRT implantation. For the prediction of 2-year mortality, the Area Under the Receiver-Operating Characteristic Curve (AUC) for model 1 was 0.77 (95% CI: 0.67–0.87; p=0.002), for SHFM was 0.54 (95% CI: 0.39–0.69; p=0.006), for EAARN was 0.57 (95% CI: 0.46–0.68, p=0.002), and for VALID-CRT was 0.62 (95% CI: 0.52–0.71; p=0.002). To predict 5-year mortality, the AUC for model 2 was 0.85 (95% CI: 0.78–0.91; p=0.001), for SHFM was 0.62 (95% CI: 0.51–0.74; p=0.003), for EAARN was 0.61 (95% CI: 0.51–0.70, p=0.002), for VALID-CRT was 0.65 (95% CI: 0.56–0.74; p=0.002). The AUCs of the machine learning based models were significantly higher than the AUCs of the pre-existing scores (DeLong test, all p<0.05). The KM curves of the quartiles were significantly separating in both models (Log-rank test, both p<0.001).

Conclusion

Our results indicate that machine learning algorithms can outperform the already existing linear model based scores. By capturing the non-linear association of predictors, the utilization of these state-of-the-art approaches may facilitate optimal candidate selection and prognostication of patients undergoing CRT implantation.

Radiofrequency ablation of focal atrial tachycardia: Benefit of electroanatomical mapping over conventional mapping

BACKGROUND

Catheter ablation is a proven therapy of focal atrial tachycardia. However limited information is available about the additional value of electroanatomical over conventional mapping methods for this specific arrhythmia.

METHODS

Consecutive catheter ablation procedures of FAT were analyzed in two cardiology centres. Only conventional mapping was used in 30 of the 60 procedures whereas additionally CARTO mapping was performed in another 30 procedures. Acute, six-month success rate, and procedural data were analyzed.

RESULTS

Localization of ectopic foci is congruent with previously published data. There was no statistically significant difference between procedure time and fluoroscopy time using additionally CARTO mapping, compared to conventional mapping only. Acute success rate was higher in procedures guided by CARTO mapping than in procedures based on conventional mapping (27/30 vs. 18/30, p = 0.0081). During the 6-month follow-up period there was a better outcome (p = 0.045) in case of CARTO guided procedures (success: 11 cases, partial success: 12 cases, failure: 4 cases) compared to conventional mapping (success: 4 cases, partial success: 18 cases, failure: 7 cases).

CONCLUSIONS

Catheter ablation of focal atrial tachycardias using the CARTO electroanatomical mapping system seems to provide higher acute and 6-month success rate compared to ablation using conventional mapping methods only.