Conventional fluorscopy-guided vs zero-fluorscopy catheter ablation of supraventricular tachycardias

Funding Acknowledgements

Type of funding sources: None.

Introduction

Traditionally, X-ray fluoroscopy is used during catheter ablation procedures. The utilisation of ionising radiation carries non-negligible stochastic and deterministic risks to the health of both the patient and the professional staff. These effects are cumulative and behave in a linear no-threshold manner and, as such, are especially important in paediatric populations (1). The importance of reducing ionising radiation exposure has been recognised by the American College of Cardiology, which recommends the ALARA (as low as reasonably achievable) principle in all interventional laboratories (2). In recent years, advances in three-dimensional electroanatomical mapping systems and their utilisation have enabled the near-zero and zero-fluoroscopy approaches to be studied (3).

Purpose

The aim of this study was to evaluate the safety and efficacy of zero-fluoroscopy catheter ablation for supraventricular tachycardias (SVT).

Methods

584 consecutive patients referred to our institution for catheter ablation of SVT were analysed. Patients were categorised into two groups; zero-fluoroscopy (ZF) group and conventional fluoroscopy (CF) group. Patient characteristics, procedural information, and follow-up data were compared.

Results

The ZF group had a higher proportion of paediatric patients (42.2% vs 0.0 %; p < 0.001), resulting in a younger age (30.9 ± 20.3 years vs 52.7 ± 16.5 years; p < 0.001) and lower BMI (22.8 ± 5.7 kg/m2 vs 27.0 ± 5.4 kg/m2; p < 0.001). Procedure time was shorter in the ZF group (94.2 ± 50.4 min vs 104.0 ± 54.0 min; p = 0.002). There were no major complications and the rate of minor complications did not differ between groups (0.0% vs 0.4%; p = 0.304). Acute procedural success as well as the long-term success rate when only the index procedure was considered did not differ between groups (92.5% vs 95.4%; p = 0.155; 87.1% vs 89.2%; p = 0.422). When repeated procedures were included, the long-term success rate was higher in the ZF group (98.3% vs 93.5%; p = 0.004). The difference can be partially explained by the operators’ preferences.

Conclusion

The safety and efficacy of ZF procedures in adult and paediatric populations are comparable to that of CF procedures.

Conduction system pacing with AV node ablation versus catheter ablation for treatment of persistent atrial fibrillation in patients with heart failure with reduced ejection fraction

Funding Acknowledgements

Type of funding sources: None.

Background

In patients with persistent atrial fibrillation (PeAF) and heart failure with reduced ejection fraction (HFrEF) current guidelines recommend treatment of AF with catheter ablation (CA) (1). Recurrence of either AF or atrial flutter, often requiring additional procedures, are not uncommon, thus optimal long-term treatment of these patients is still unknown. Recently conduction system pacing (CSP), with more physiological ventricular activation, has made the ‘’pace and ablate’’ strategy an attractive alternative for the treatment of PeAF refractory to medical therapy (2).

Purpose

Long term data comparing CA with conduction system pacing and AV node ablation (CSP/AVNa) for treatment of patients with PeAF and HFrEF is lacking. Hence, we sought to compare clinical outcomes of both treatment modalities.

Methods

In a retrospective study consecutive patients under 75 years of age, with PeAF and left ventricular ejection fraction (LVEF) less than 50%, treated with CSP/AVNa from 2018 to 2021 in UMC Ljubljana were included. A control patient treated with CA for PeAF matched in age, sex and LVEF was assigned for each included CPS/AVNa patient. Both groups were compared for procedure-related characteristics, echocardiographic parameters, hospitalisations for heart failure and all-cause mortality.

Results

Among 771 patients referred for interventional treatment of AF, 23 patients treated with CSP/AVNa were included and compared with 23 CA matched controls. The general characteristics of both groups are summarised in Table 1. The mean follow-up was 20 ± 10 and 21 ± 8 months for CPS/AVNa and CA group, respectively (p=0.76). In CPS/AVNa group 83% received his bundle pacing and 17% left bundle branch area pacing. A selective CSP was achieved in 43% of CSP/AVNa patients. In addition to pulmonary vein isolation, additional ablation lines were performed in 35% of patients in the CA group. Significant improvement in LVEF was observed in both groups, 12% ± 11% (p<0.001) in CSP/AVNa and 21% ± 12% (p<0.001) in CA group. Hospitalisations for HF were rare during the follow-up, with 9% in CSP/AVNa and 4% in the CA ablation group (p=0.561). All-cause mortality was 9% in CSP/AVNa and 0% in CA group (p=0.153). However, major comorbidities were more common in the CSP/AVNa group than in the CA group, 3.4 ± 1.6 and 2.3 ± 1.5, respectively (p=0.017). Procedure-related characteristics are summarised in Table 1. In each group, 2 minor procedure-related adverse events were observed: 2 acute rises in pacing threshold post-AVNa in CSP/AVNa group and puncture site hematoma and transient pericardial effusion in CA group.

Conclusion

In patients with PeAF and HFrEF, CSP/AVNa treatment strategy seems to derive similar clinical outcomes compared to CA approach. Larger prospective randomised data are needed to further confirm these initial findings and determine optimal long-term treatment strategy for this group of patients.

Biventricular versus conduction system pacing after atrioventricular node ablation in heart failure patients with atrial fibrillation

Funding Acknowledgements

Type of funding sources: None.

Background

Atrioventricular node ablation (AVNA) with biventricular (BiV) pacing is an established treatment option for heart failure (HF) patients with drug refractory atrial fibrillation (AF) (1). However, compared to conduction system pacing (CSP) modalities, including His bundle pacing (HBP) and left bundle branch pacing (LBBP), BiV pacing delivers non-physiological ventricular activation (2).

Purpose

To compare clinical outcomes of BiV pacing and both CSP modalities in HF patients with symptomatic AF who underwent AVNA.

Methods

Consecutive AF patients with LV ejection fraction (LVEF <50%) who received either BiV pacing or CSP in conjunction with AVNA between May 2015 and July 2021 were retrospectively analysed. Procedural characteristics, electrocardiographic, echocardiographic, and clinical parameters were assessed at baseline and 6 months after the procedure.

Results

Fifty-five patients (male 43.6%, age 71 years (IQR 10), LVEF 39% (IQR 14)) were included. Thirteen patients (23.6%) received BiV pacing, 30 patients (54.5%) HBP and 12 patients (21.8%) LBBP. All groups had similar baseline characteristics, acute success rate and adverse events. Post-procedural QRS duration was significantly shorter (p<0.01) in CSP (118 ms (IQR 28)) than in BiV pacing (172 ms (IQR 18)). While NYHA class improved in both HBP (p<0.01) and LBBP (p=0.01), it did not improve in BiV group (p=0.1) At follow-up, end systolic volume (ESVi) decreased in both HBP (48±20 to 32±12 mL/m2, p<0.01) and LBBP (62±22 to 52±22 mL/m2, p=0.02), but did not differ in BiV pacing group (51±12 to 53±14 mL/m2, p=0.6). Similarly, LVEF increased in HBP (form 39% (IQR 16) to 53% (IQR 14), p<0.01) and LBBP (from 41% (IQR 23) to 40% (IQR 25), p=0.04), but did not change in BiV group (from 38% (IQR 5) to 37% (IQR 6), p=0.9). Significantly lower (p<0.01) pacing thresholds were achieved in LBBP (0.75 V at 0.5 ms (IQR 0.3)) than in HBP group (1.0 V at 0.5 ms (IQR 1)). Two patients in HBP group were switched to right ventricular pacing due to rise in HBP threshold. In the remaining patients threshold remained stable during follow-up.

Conclusion

Conduction system pacing modalities showed superior symptomatic and echocardiographic improvement compared to BiV pacing after AVNA. While LBBP offered lower and more stable pacing parameters, there were no differences in clinical outcomes and echocardiographic remodelling when compared to HBP.

P508Biventricular pacing versus His bundle pacing after atrioventricular node ablation in heart failure patients with permanent atrial fibrillation and narrow QRS

Background

Atrioventricular (AV) node ablation with biventricular (BiV) pacemaker implantation is a feasible rate control strategy for symptomatic permanent atrial fibrillation (AF) with rapid ventricular response and tachycardia-induced heart failure (HF). However, certain controversy exists since BiV pacing delivers non-physiological ventricular resynchronization and does not return left ventricular (LV) activation times to those seen in individuals with intrinsically narrow QRS. Permanent His bundle pacing (HBP) is a physiological alternative to conventional and BiV pacing. By capturing the native conduction system, depolarization of the ventricles through the His-Purkinje system induces normal synchronous ventricular activation.

Purpose

The aim of the study was to compare short-term outcomes between BiV pacing and HBP after AV node ablation in HF patients with symptomatic permanent AF and narrow QRS.

Methods

A total of 25 consecutive HF patients with permanent AF and narrow QRS (≤110 ms) who underwent AV node ablation in conjunction with BiV pacing or HBP in our centre were enrolled. Post-implant QRS duration, echocardiographic data, and New York Heart Association (NYHA) functional class were assessed in short-term follow-up.

Results

Among 25 HF patients (aged 68 ± 7 years, 52% female, QRS 96 ± 9 ms, LVEF 37 ± 7%, NYHA II-IV), 13 received BiV pacing and 12 HBP. Implant and ablation procedures were acutely successful in both groups. In BiV group 1 patient had a LV lead dislodgement and 1 patient in the HBP group had an acute HB lead threshold increase after AV node ablation. In HBP group post-implant QRS duration was shorter compared to BiV (103 ± 15 ms vs. 177 ± 13 ms, p < 0.001). At a median follow-up of 6 months, patients treated with HBP had greater increase in LV ejection fraction compared to BiV (44 ± 10 vs. 37 ± 6, p = 0.045). A trend toward greater reduction of LV volumes (EDV 119 ± 54 ml vs. 153 ± 33 ml, p = 0.07; ESV 75 ± 34 ml vs. 97 ± 26 ml, p = 0.09) and improvement of NYHA class (2.1 ± 0.7 vs. 2.7 ± 0.8, p = 0.08) was also observed in HBP group compared to BiV group.

Conclusion

In rate control refractory HF patients with permanent AF and narrow QRS atrioventricular node ablation in conjunction with HBP demonstrated superior electrical resynchronization and greater increase in LV ejection fraction compared to BiV pacing. Larger prospective studies are warranted to address clinical outcomes between both pace and ablate strategies.

233Conventional fluoroscopy guided vs zero-fluoroscopy catheter ablation of supraventricular tachycardias

Funding Acknowledgements

None

Introduction

Conventionally, catheter movement and placement during catheter ablation (CA) is guided by X-ray fluoroscopy. In recent years, an ‘as low as reasonably possible’ principle was established to minimize the ionizing radiation dose received by the patient and the operator. Zero-fluoroscopy approach is at the extreme end of the spectrum of this principle. With exclusion of X-ray fluoroscopy, three-dimensional electroanatomical mapping system and intracardiac echocardiography are used for catheter guidance during ablation procedures.

Purpose

The aim of our study was to assess and compare procedural parameters and clinical outcomes of conventional X-ray fluoroscopy guided and zero-fluoroscopy CA for treatment of supraventricular tachycardias.

Methods

Retrospective analysis included CA procedure between April 2014 and May 2019. Five hundred and thirteen (513) patients were selected for analysis; they had confirmed diagnosis of atrioventricular nodal reentry tachycardia (AVNRT) or atrioventricular reentry tachycardia (AVRT). Patients were divided into two groups based on the use of fluoroscopy (conventional approach group - CG; zero-fluoroscopy group - ZF). Procedural data and clinical outcomes were analyzed. Two groups were compared using chi-squared test or Mann-Whithney U test when appropriate.

Results

There were 249 patients (44.2% males) in CG group, and 260 patients (47.5% males) in ZF group. ZF group included 113 (43.5%) pediatric patients. The groups differed in mean age (53.4 ± 16.4 years vs 30.0 ± 19.8 years (CG vs ZF), p < 0.001), postprocedural use of antiarrhythmic agents or beta blockers (55.3% vs 17.0% (CG vs ZF), p < 0.001) and type of arrhythmia (72.3% vs 60.6% AVNRT (CG vs ZF), p = 0.003).

In CG group, all procedures were performed using radiofrequency (RF) energy, whereas in ZF group, cryoablation was used in 18.3% of procedures at the discretion of the operator. Mean procedural duration was longer in CG group (100.1 ± 48.8 vs 90.4 ± 83.0 minutes, p < 0.001). The mean fluroscopy time was 13.6 ± 9.3 minutes and mean dose area product was 554.1 ± 713.6 mGycm2 in the CG group. Acute success rate was higher in CG group (95.7 vs 90.7%, p = 0.027). However, the arrhythmia-free survival rate after 13.8 ± 11.0 months of follow-up was lower in the CG group (90.9 vs 96.5%, p = 0.009). Mean number of procedures per patient was 1.04 in the CG group and 1.14 in the ZF group (p < 0.001). There were no severe complications.

Conclusions

Zero-fluoroscopy CA of supraventricular tachycardias is associated with lower procedural success rate, but higher long-term arrhythmia-free survival rate when compared to conventional fluoroscopy guided procedures. It is possible, that these differences are stemming from somewhat different patient populations in both groups.