Dual-Energy Lattice-Tip Catheter for VT Ablation — Early Feasibility (2024)

Authors, Journal, Affiliations, Type, DOI

• Authors: Petr Peichl, Dan Wichterle, Filip Schlosser, Predrag Stojadinović, Vojtěch Nejedlo, Eva Borišincová, Josef Marek, Peter Štiavnický, Jana Hašková, Josef Kautzner
• Journal: Europace 2024;26:euae275
• Affiliations: Department of Cardiology, Institute for Clinical and Experimental Medicine (IKEM), Prague; Cardiac Ablation Solutions, Medtronic, Minneapolis
• Type: Prospective observational case series, 18 consecutive patients, single centre (January–June 2024)
• DOI: 10.1093/europace/euae275

Overview

The first clinical series of ventricular tachycardia ablation with the Affera Sphere-9 dual-energy lattice-tip system — a 9-mm expandable tip with nine surface microelectrodes that maps, ablates with high-energy RF and then consolidates with pulsed field through the same catheter. In 18 patients, two-thirds of whom had already failed conventional irrigated-tip ablation and 22% of whom were in electrical storm, mapping was rapid (≈4,500 points per chamber in ~18 minutes) and non-inducibility was achieved in 89%, with 78% free of ventricular arrhythmia at three months. The paper's value lies in the complications it documents: epicardial PF applications caused angiographic coronary spasm in three of four patients (all resolving with intracoronary nitrates, at a tip-to-artery distance of 7 ± 3 mm), while no phrenic nerve palsy occurred even with delivery directly on the nerve; epicardial PF was explicitly not transmural. It also reports the practical penalty of a large tip — pace mapping and entrainment were often impossible, and one VT was unreachable under the tricuspid valve until a 4-mm catheter was used at redo.

Keywords

Catheter ablation; ventricular tachycardia; pulsed field; radiofrequency ablation

Key Takeaways

Population and methods

• 18 patients, 55 ± 15 years, 94% male; structural heart disease in 94% (coronary disease 56%, non-ischaemic cardiomyopathy 35%, congenital heart disease 6%, hypertrophic cardiomyopathy 6%); LVEF 34 ± 10%; 66% after ≥1 failed RF ablation (range 1–3); 22% in electrical storm; ICD in 94%. One patient had idiopathic focal VT from the crux.
• All procedures under general anaesthesia, with the Affera mapping system and intracardiac echocardiography; transseptal or retrograde LV access; ACT 300–350 s.
• Strategy: high-energy RF first (30 s per lesion), because electrogram change can be assessed after RF but may vanish when PF is used first; PF (5 s, repeated up to three times per site) added to consolidate. PF was never used near the proximal conduction system and was the only energy in the epicardial space.
• Endpoint: abolition of abnormal signals/late potentials, often electrical isolation of the scarred segment; acute success = non-inducibility with the same stimulation protocol.

Mapping performance

• 4,452 ± 1,724 points (RV) and 4,581 ± 2,095 points (LV); mapping time 18.3 ± 9.6 and 18.7 ± 6.6 minutes respectively. Mapping was perceived as easy, but perimitral and peritricuspid regions needed ICE to place the catheter.
• Substrate location: anterior/anteroseptal LV 28%, inferior LV 28%, lateral LV 22%, RV 17%, periaortic 6%.
• Pace mapping and entrainment were often difficult or impossible — the pacing electrodes on the lattice surface are small — which is the main reason RF was used first.

Ablation

• 12 ± 7 RF and 8 ± 9 PF applications per patient; epicardial access in 22%; procedural duration 157 ± 31 min; fluoroscopy 5.2 ± 4.0 min.
• PF did not induce VF or sustained VT in any patient, but myocardial capture was commonly seen during PF delivery — so when VT terminated during PF, it was unclear whether the isthmus had been eliminated or the VT had been overdrive pace-terminated.
• Epicardial PF did not produce transmural lesions, assessed by unchanged corresponding endocardial signals.
• Acute non-inducibility 16/18 (89%). Failures: one patient with a pericardial patch over a post-infarction ventricular septal defect (later treated with stereotactic radiotherapy) and one with an inaccessible epicardial lateral LV circuit due to adhesions.
• Ventricular-arrhythmia-free survival at 3 months: 78%. Four recurrences — two in the procedural failures, one ATP-treated episode, and one non-ischaemic inferior basal RV VT that required a 4-mm catheter inserted under the inferior tricuspid leaflet at redo, because the lattice tip could not fit the narrow space.

Safety

• Coronary spasm in 3 of 4 patients undergoing epicardial ablation on angiography before/after PF; ischaemic ECG changes in only one. Mean distance from artery to catheter centre was 7 ± 3 mm when spasm occurred; none at 21 mm. All resolved with intracoronary nitroglycerine (0.5 mg upwards, up to 2–3 mg or until systemic hypotension). The authors advise coronary angiography before and after epicardial PF so that nitrates can be given immediately.
• No phrenic nerve palsy in the three patients with epicardial PF near the nerve (one directly on a site with phrenic capture, two within 1–2 cm) — consistent with the 0.06% rate in the 17,000-patient AF registry cited.
• One stroke, resolving within a month without sequelae, in a patient with hypertrophic cardiomyopathy and a history of LV aneurysm thrombus despite a normal contrast echo and ACT >300 s; source unknown.
• hsTnT rose from 36 ± 26 to 995 ± 580 ng/L (P<0.01) — about three times lower than typical rises after AF ablation, attributed to fewer PF applications and ablation of scar rather than healthy tissue. The authors regard this as reassuring in impaired ventricles.

The authors' energy comparison

• RF creates larger lesions than PF experimentally, and RF effects are immediately assessable; PF penetrates healthy, scarred and fatty tissue better, but acute PF lesions have a much larger zone of reversible injury, and the group's earlier solid-tip PF experience showed more temporary suppression with more recurrence.
• PF spares ganglionic plexi and nerves, is unlikely to cause steam pops, and experimentally causes coronary spasm followed by only mild chronic neointimal change — whereas RF over a coronary can thrombose it. This is the argument for PF being able to work close to coronary arteries.
• PF does not exceed moderate myocardial damage; extensive damage would risk pump failure in already-impaired ventricles.

Practical penalties of a large tip

• Narrow spaces (between atrioventricular valves and the myocardial wall, endocardial excavations, papillary muscle bases) can be unreachable even with real-time imaging; ICE is essential, and a complementary 4-mm catheter may be needed.
• Post-infarct thinning and smoothing actually favours the lattice tip; non-ischaemic cardiomyopathy with trabeculation, variable thickness and intramural substrate is harder.

Limitations of the document

• Small, single-centre, prospective observational series with no control group and no comparison with conventional RF or other PFA platforms.
• Mixed energies. RF and PF were combined in most patients (PF to consolidate RF), so the specific contribution of PF to efficacy, complications and troponin release cannot be separated.
• Short follow-up (3 months) with ICD interrogation and clinical history rather than continuous monitoring.
• Broad substrate mix and operator-selected strategy, so subgroup inference is impossible.
• No prophylactic nitrates were given before epicardial PF, leaving open whether spasm is preventable rather than merely treatable.
• Conflict of interest: one author is a Medtronic employee; two others report Medtronic and industry honoraria.

Key Concepts Mentioned

• concepts/Ventricular-PFA — biophysics and clinical use
• concepts/Ventricular-PFA — ventricular application and device comparison
• concepts/VT-Ablation — procedure, mapping and endpoints
• concepts/Epicardial-VT-Ablation — epicardial access, spasm and phrenic risk
• concepts/VT-Ablation-Ischemic-Cardiomyopathy · concepts/VT-Ablation-Nonischemic-Cardiomyopathy — the two dominant substrates
• concepts/PVC-Mapping-Ablation — reachability problems with large tips

Key Entities Mentioned

• Sphere-9 lattice-tip catheter, Affera mapping/ablation system (Medtronic)
• AcuNav intracardiac echocardiography (Siemens); Agilis-type deflectable sheath
• IKEM, Prague

Wiki Pages Updated

• Created: wiki/sources/lattice-tip-vt-europace-2024.md
• Updated: wiki/concepts/Ventricular-PFA.md
• Updated: wiki/concepts/Pulsed-Field-Ablation.md, wiki/concepts/Epicardial-VT-Ablation.md
• Updated: wiki/sourceindex.md, wiki/wikiindex.md, log.md