Feasibility and safety of strategic multielectrode positioning guided by S3 protocol for hemodynamically unstable ventricular tachycardia: the S3-STaMP project
R Pittorru, T Rosseel, N Pierucci, M Regany-Closa, P Bhagirath, F Graterol, F Migliore, J B Guichard, J M Tolosana, E Guasch, E Arbelo, J Brugada, L Mont, A Porta-Sanchez, I Roca-LuqueAbstract
Background
Substrate-based ablation is the preferred strategy for non-inducible or non-tolerated ventricular tachycardia (VT), where activation or entrainment mapping is unfeasible. Advances in high-density and functional electroanatomical mapping with imaging have improved detection of slow-conduction areas essential for scar-related VT ablation. In non-hemodynamically tolerated VT, data on efficient and safe identification of diastolic components without prolonged mapping are limited. The STrategic Multielectrode Positioning (STaMP) approach was proposed for this purpose, but evidence on feasibility, impact, and the role of functional mapping remains scarce.
Objective
To evaluate the feasibility and safety of STaMP mapping during non-tolerated monomorphic VT and the role of functional mapping with the S3 protocol.
Methods
We retrospectively analyzed patients undergoing scar-related VT ablation (2022–2025) at Hospital Clínic, Barcelona. All underwent late gadolinium enhancement cardiac MRI with automated channel analysis (ADAS3). An S3 (600-VERP+30, VERP+50 ms) right ventricular pacing protocol was used to identify slow conduction zones. Of 40 patients with non-tolerated VT, 30 underwent STaMP mapping by placing a high-density catheter in the slowest conduction area during S3. STaMP positivity was defined by electrograms during any phase of diastole. The PAINESD score was calculated, and acute hemodynamic decompensation (AHD) assessed. AHD was defined as intraprocedural or early (<12 h) pulmonary edema or hypotension requiring urgent support.
Results
Thirty patients (mean age 63 ± 12 years; 96.6% male; LVEF 35 ± 10%) were included; 20 (66.6%) had ischemic cardiomyopathy and 5 (16.6%) required an epicardial approach. STaMP mapping was positive in 22 (73.3%) and negative in 8 (26.7%); full diastolic pathways were recorded in 12/22 positives (60%). Mean mapping time was 20 ± 12 s (median 18, IQR 12–28), shorter in STaMP-positive vs negative (14 vs 34.5 s, p=0.003). Deceleration zones in STaMP-positive areas showed slower conduction (120 ms, Q1–Q3 96–130 vs 99 ms, Q1–Q3 82–124; p=0.016). LGE-CMR channels were more frequent in STaMP-positive regions (95.4% vs 50%, p=0.011). In 27.3%, the STaMP-positive area appeared only in the S3 map. Despite 16 high-risk patients per PAINESD, no AHD occurred. During a median follow-up of 19 months (IQR 13–29), VT recurrence was 23%, with no significant difference between groups (log-rank p=0.20).
Conclusions
STaMP mapping during non-tolerated VT is feasible in most patients and rapidly delineates critical diastolic pathways. Functional mapping with the S3 protocol enhances identification of positive regions. STaMP-positive zones show slower conduction and correlate with CMR-defined channels. The approach proved safe even in high-risk patients, supporting its value as a practical strategy to improve scar-related VT ablation outcomes.STaMP positive after S3 mappingSTaMP negative after S3 mapping