Modern technologies for radiofrequency pulmonary vein isolation. Comparison of radiofrequency balloon catheter with high power-short duration ablation in patients with paroxysmal atrial fibrillation

Funding Acknowledgements

Type of funding sources: None.

Background

Pulmonary vein isolation (PVI) is an established therapy for symptomatic atrial fibrillation (AF). Traditional point by point ablation can be time consuming requiring advanced training. Novel radiofrequency (RF) ablation techniques sought to facilitate PVI. Point by point ablation using high power short duration (HPSD) settings has already shown to be safe and effective whereas there is paucity of data using a novel multi-electrode balloon catheter (Heliostar™, Biosense Webster, CA, USA).

Purpose

We aimed to assess procedure characteristics, efficacy, and safety of the Heliostar™ RF-balloon catheter in direct comparison with the latest RF ablation technique.

Methods

All patients undergoing PVI using the Heliostar™ between September and November 2021 were included in this ongoing single center registry. Procedural data and outcome were assessed and compared with data from patients undergoing initial PVI for paroxysmal AF with the HPSD approach from our specifically designed database. A power setting of 70W/7s (70W/5s at posterior wall) was considered as HPSD.

Results

A total of 51 consecutive patients (61±16 years, 49% male) were included. Of those 13 patients undergoing RF-balloon and 38 patients HPSD ablation. Baseline parameters did not differ between groups. Acute PVI was achieved in all patients. For every RF-application with the RF-balloon all necessary criteria were met: Inflation index was between 0.9 and 1.0 and a minimum of 9/10 electrodes were within impedance range. A mean of 2.8±1.4 applications per vein (LSPV 3.2±2.9, LIPV 2.6±2.5, RSPV 2.8±2.0 and RIPV 1.8±0.8) were necessary to achieve durable isolation. The mean maximum esophageal temperature was 40.2±0.8°C. When comparing procedural parameters with HPSD no statistically significant difference was seen regarding procedure duration (Heliostar™ 111±28min and HPSD 100±25min; p=0.3) and left atrial dwell time (Heliostar™ 90±23min and HPSD 80±26min; p=0.08). Fluoroscopy time (Heliostar™ 17±4min and HPSD 13±5min; p=0.005) and dose (Heliostar™ 3961±1325mGy*cm2 vs. HPSD 3153±1833mGy*cm2; p=0.04) were higher in the Heliostar™ group. No major complication occurred in both groups. A three month follow up was available for 10 patients in the Heliostar™ and for 38 patients in the HPSD group. All 10 Heliostar™ patients and 79% of the HPSD patients were free from atrial arrhythmias at follow up.

Conclusion

The novel multi-electrode RF-balloon has shown to be safe and effective in the first clinical routine AF ablation procedures. The tendency towards longer LA dwell times, procedure durations and the significantly higher fluoroscopy exposition in comparison with the HPSD PVI can be attributed to the learning curve applying a new ablation system. More experience is needed in the future to determine the benefits of the novel RF-balloon.

Validation of seven risk scores in a prospective and independent cohort: the challenge of predicting recurrence after atrial fibrillation ablation

Funding Acknowledgements

Type of funding sources: None.

Background

Several predictive scores for atrial fibrillation (AF) recurrence after ablation have been developed, only some of these are validated in prospective cohorts. The predictive value of such scores has thus far been limited, and many have not been compared with one another.

Aims

We sought to compare the predictive value of seven previously described risk scores ((CHA2DS2 and CHA2DS2-VASC, HATCH, APPLE, CAAP-AF, BASE-AF2, MB-LATER) for prediction of AF recurrence risk at 12 months after AF ablation. Further, we aimed to identify additional variables to predict recurrences after AF ablation.

Methods

We analyzed data from of our prospective digital AF ablation registry to compare the previously published scores in an independent and prospective cohort (n=883, 50.8% with paroxysmal AF). Patients were undergoing de-novo ablation of AF received a pulmonary vein isolation (PVI) using radiofrequency (RF) ablation or cryoablation. Ablation procedures for recurrences of AF after initial PVI included re-isolation of the pulmonary veins by RF ablation, with additional substrate modification at the operators’ discretion.

Early recurrence and recurrence after ablation were defined as any AF or atrial tachycardia episode lasting ≥ 30 s in the first 3 months after ablation and from the end of the 3-month period to 12 months after ablation. Follow-up of patients was scheduled at regular intervals 3 and 12 months after ablation, and included Holter-ECG, 12-lead ECG and history. Outcome-relevant data from implanted cardiac devices (CIED), such as 2-chamber ICD and pacemakers, or implantable loop recorders were analyzed when available.

A predefined subgroup analysis was performed in the following subgroups: first procedure vs. redo procedure, paroxysmal vs. persistent AF, and RF ablation vs. cryoablation.

Results

The BASE-AF2 (AUC 0.630, p<0.001), MB-LATER (AUC 0.612, p<0.001) CAAP-AF (AUC 0.591, p<0.001), APPLE (AUC 0.591, p<0.001) and CHA2DS2-VASC (AUC 0.547, p=0.018) scores had a significant but modest predictive value for 12-month AF-recurrence. None of these scores was significantly superior. Other previously published scores had no predictive value. There was no difference in the predictive value for 12-month recurrence of AF between first procedure vs. redo procedure and RF ablation vs. cryoablation. Unlike other scores, MB-LATER showed better predictive value for paroxysmal vs. persistent AF (AUC 0.632 vs. 0.551, p=0.038). In the multivariate logistic regression, only age (p=0.006), number of prior electrical cardioversions (p<0.001) and early AF recurrence (p<0.001) were independent predictors of 12-month AF recurrence.

Conclusion

Despite numerous available scores, predicting recurrences after AF ablation remains challenging. New simple and robust predictors are needed, potentially based on diagnostic interventions, as well as novel genetic, functional and anatomic parameters.

Impact of pacing output and cycle length on qrs morphology in ablation of premature ventricular contractions (PACE-MAP-Trial)

Funding Acknowledgements

Type of funding sources: None.

Background

Pace mapping is an established technique to localize the origin of premature ventricular contractions (PVC). The QRS morphology induced by endocardial pacing is compared with a previously recorded template of the target arrhythmia. Based upon historic in-vitro models pacing at the arrhythmia’s coupling interval (CI) and stimulation threshold has become the gold standard in pace mapping.

Purpose

There is a paucity of data supporting pacing at the CI and stimulation threshold as the gold standard for pace mapping. In this prospective study, we sought to assess systematically the impact of variations of pacing output and cycle length on the resulting QRS morphology during pace mapping in the context of PVC ablation (NCT05061498).

Methods

All patients undergoing ablation of idiopathic PVC were prospectively enrolled in this study. Pace mapping was performed using four different parameter settings: (1) A predefined fixed burst at maximum output (10V/2ms), (2) fixed burst at stimulation threshold, (3) coupling interval at maximum output and (4) coupling interval at stimulation threshold. Pacing cycle length (PCL) of the fixed burst was defined as follows: for a CI ≤450ms = PCL of CI+100ms and for a CI ≥450 = PCL of CI-100ms. Using an automated waveform comparison algorithm, the resulting QRS complexes were matched with the clinical PVC, and with the gold standard. For every parameter setting the mean of the matching percentage of three QRS complexes entered the analysis.

Results

We report data of the first 22 consecutive patients (53±15 years, 64% female) enrolled in this ongoing study between May and November 2021. The pacing protocols were performed at 39 different sites: 5/39 epicardially via great cardiac vein, 15/39 in the RVOT 12/39 and 7/22 in the left ventricular cavity. When comparing the QRS morphologies resulting from the four different pace mapping settings with the clinical PVC, the univariate analysis revealed no difference between groups (p=0.9). Furthermore, there was no difference comparing the paced QRS morphologies at different output and cycle length to the gold standard of threshold pacing at coupling interval (p=0.9).

Conclusion

Variations of pacing output and stimulation cycle length during pace mapping does not affect QRS morphology during PVC ablation. Applying a modern automated waveform comparison tool, no advantage was observed when comparing with the gold standard. It is therefore reasonable to assume, that pace mapping can be performed using an easily applicable setting of a fixed burst at maximum pacing output.

Procedural and outcome impact of obesity in cryoballoon versus radiofrequency pulmonary vein isolation in atrial fibrillation patients

PURPOSE

Cryoballoon (CB) ablation and radiofrequency (RF) ablation are the most common techniques for pulmonary vein isolation (PVI) in patients with symptomatic atrial fibrillation (AF). An increasing number of patients undergoing PVI are obese. To address the paucity of data on outcomes of CB- vs. RF-based PVI in relation to body mass index (BMI) of AF patients.

METHODS

All patients undergoing de novo PVI between 01/2018 and 08/2019 at University Hospital Cologne were included in this retrospective analysis. Patients of each group (CB-PVI vs. RF-PVI) were analyzed based on their BMI. Hereafter, procedural characteristics and AF recurrence rate were compared regarding different BMI groups.

RESULTS

A total of 526 patients (62% male, 65±11 years) underwent successful de novo PVI (320 CB and 206 RF). In obese patients, two differences in procedural characteristics were noted: A significantly increased contrast medium volume in CB group and a lower fluoroscopy dose in RF group: contrast medium: CB 50 [40-80] vs. RF 20 [20-30], p<0.001; fluoroscopy dose: CB 392.4 [197.9-995.9] vs. RF 282.5 [139.8-507.2], p<0.001. The complication rate was equal throughout all BMI groups, regardless of CB or RF usage. For obese patients, a trend toward a higher AF recurrence rate was revealed after RF-PVI as compared to CB-PVI. In line with previous studies, the overall procedure time was significantly shorter with CB-PVI regardless of BMI.

CONCLUSION

For obese patients, CB-PVI is similarly safe and effective as RF-PVI. The significantly shorter procedure time for CB-PVI may minimize potential obesity-related complications. However, the lower contrast medium quantity and fluoroscopy dose in RF-PVI must be considered. AF recurrence rates were comparable between CB-PVI and RF-PVI.

Combined non-invasive assessment of endothelial shear stress and molecular imaging of inflammation for the prediction of inflamed plaque in hyperlipidaemic rabbit aortas

AIMS

To evaluate the incremental value of low endothelial shear stress (ESS) combined with high-resolution magnetic resonance imaging (MRI)- and computed tomography angiography (CTA)-based imaging for the prediction of inflamed plaque.

METHODS AND RESULTS

Twelve hereditary hyperlipidaemic rabbits underwent quantitative analysis of plaque in the thoracic aorta with 256-slice CTA and USPIO-enhanced (ultra-small superparamagnetic nanoparticles, P904) 1.5-T MRI at baseline and at 6-month follow-up. Computational fluid dynamics using CTA-based 3D reconstruction of thoracic aortas identified the ESS patterns in the convex and concave curvature subsegments of interest. Subsegments with low baseline ESS exhibited significant increase in wall thickness and plaque inflammation by MRI, in non-calcified plaque burden by CTA, and developed increased plaque size, lipid and inflammatory cell accumulation (high-risk plaque features) at follow-up by histopathology. Multiple regression analysis identified baseline ESS and inflammation by MRI to be independent predictors of plaque progression, while receiver operating curve analysis revealed baseline ESS alone or in combination with inflammation by MRI as the strongest predictor for augmented plaque burden and inflammation (low ESS at baseline: AUC = 0.84, P < 0.001; low ESS and inflammation by molecular MRI at baseline: AUC = 0.89, P < 0.001).

CONCLUSION

Low ESS predicts progression of plaque burden and inflammation as assessed by non-invasive USPIO-enhanced MRI. Combined non-invasive assessment of ESS and imaging of inflammation may serve to predict plaque with high-risk features.