https://doi.org/10.1007/s00392-025-02737-x
1Herz- und Diabeteszentrum NRW Klinik für Elektrophysiologie/ Rhythmologie Bad Oeynhausen, Deutschland; 2Herz- und Diabeteszentrum NRW Klinik für Elektrophysiologie/Rhythmologie Bad Oeynhausen, Deutschland; 3GZO Spital Wetzikon Klinik für Kardiologie und Angiologie Wetzikon, Schweiz; 4Klinik für Herzchirurgie Herzchirurgie Bad Oeynhausen, Deutschland; 5Herz- und Diabeteszentrum NRW Allgemeine und Interventionelle Kardiologie/Angiologie Bad Oeynhausen, Deutschland
Background
Radiofrequency ablation is a key treatment for scar-related ventricular tachycardia (VT), especially in patients unresponsive to antiarrhythmic drugs. Procedural success is commonly assessed using programmed ventricular stimulation (PVS) to test for VT non-inducibility, yet its prognostic value remains unclear, and no standardized protocol exists.
Objectives
In a retrospective single-center study patients undergoing VT ablation (2020–2024), outcomes between those evaluated with a standardized 330S4 PVS protocol and those assessed with non-standardized strategies were compared. The goal was to evaluate the 330S4 protocol's feasibility and predictive value regarding VT recurrence, hospitalization, and ICD therapies.
Methods
Both ischemic and non-ischemic etiologies were part of our database. Procedural data were extracted from a prospective registry and included mapping time, fluoroscopy time, radiation dose, and stimulation protocol.
Ablation was performed under general anesthesia using 3D electroanatomical mapping. Substrate modification targeted low-voltage areas, late potentials, and fractionated signals, guided by anatomical, activation, and/or pace mapping. RF energy was used in all procedures.
Post-ablation, PVS was performed using either a standardized 330S4 protocol (pacing at 500, 430, 370, and 330 ms with up to four extrastimuli) or alternative protocols at the operator’s discretion. Following the introduction of the 330S4 protocol, it was systematically applied in all patients and outcomes were compared with those of patients treated prior to its implementation.
The procedural endpoint was defined as non-inducibility of any clinically relevant ventricular tachycardia. In cases where such a VT was inducible, targeted ablation was repeated until no further inducible VT was observed.
Results
A total of 163 consecutive patients were included in this retrospective analysis. Among them, 57.1% had ischemic cardiomyopathy (ICM), and 42.9% had non-ischemic cardiomyopathy (NICM). The majority were male (87.3%), with a mean age of 64.1 ± 11.6 years. Prior to ablation, 61.8% were on amiodarone therapy, and 23.6% had experienced a VT storm. Baseline risk was assessed using the PAINESD score, with 46.7% scoring <13, 40.6% scoring between 13 and 17, and 12.7% scoring >17 (Table 1).
52 patients received 330S4 stimulation, and 111 underwent alternative protocols. The predefined procedural endpoint was achieved in all patients.
Over a mean follow-up of 12 months, 90% of patients in the 330S4 group (n = 47) remained free from ATP therapy, ICD shocks, and hospitalizations. In comparison, among patients treated with alternative protocols, freedom from ATP was achieved in 80% (n = 89), from ICD shocks in 85% (n = 94), and from hospitalization in 80% (n = 89).
The 330S4 group had higher PAINESD scores and represented a smaller, higher-risk cohort. Despite this, Kaplan Meier analyses demonstrated a non-significant trend towards freedom from ATP events, ICD shocks, and hospitalizations over 12 months (long-rank p= 0,117, p= 0,163, p= 0,135).
Conclusion
The standardized 330S4 protocol showed a consistent trend toward fewer adverse events post-VT ablation, suggesting potential benefit for risk stratification. While not statistically significant, these findings support efforts to standardize post-ablation PVS and warrant further prospective validation.