Pro-arrhythmogenicity of single-tip and multi-spline mapping catheters in post-myocardial infarction ventricular tachycardia ablation: a prospective, international, two-center experience

Background Substrate mapping using multielectrode catheters is increasingly used for post-myocardial infarction (MI) ventricular tachycardia (VT) avoiding repeated VT induction and mapping during VT. However, these catheters may provoke mechanically induced ventricular arrhythmias with hemodynamic compromise, requiring cardioversion and risking map shifts. Aims This study compares pro-arrhythmogenicity between single-tip and multi-spline catheters during functional substrate mapping preceding post-MI VT ablation. Methods Consecutive patients referred for VT ablation at two centers underwent mapping in random order with a multi-spline catheter (Octaray or Pentaray) and a single-tip QDOT catheter. Mapping of the infarct areas was performed during baseline rhythm and right ventricular stimulation with a drive cycle lengths of 500ms (S1) and during application of a short-coupled extrastimuli (S2). The study protocol was terminated for safety reasons when either (i) two mechanically induced VTs required electrocardioversions (ECV), (ii) recurrent ATP-treated mechanical VTs caused hemodynamic compromise, or (iii) excessive mechanical ectopy impaired catheter contact. Mapping time, number of points, and mechanically induced arrhythmias were assessed. Results Thirty post-MI patients were included (baseline characteristics shown in Graphical abstract). Functional substrate mapping with the multispline catheter was faster than with the single-tip catheter (26±9 minutes vs 60±16 minutes, respectively, p-value <0.001) with more acquired points (539±320 vs 264±72 mapping points, p-value<0.001). Mechanically induced VTs were more frequent with the multispline catheters compared to the Qdot catheter (median 2 VTs per patient [IQR 1–4] vs 0 [IQR 0–3], p<0.05). Overall, 17 patients (57%) experienced at least one mechanically induced VT. In sixteen patients (53%) the multispline catheter mechanically induced ≥1 VT, while in only five patients (17%) the single tip catheter mechanically induced VT (p-value <0.001). Three patients had mechanically induced polymorphic VT/VF with a multispline catheter, none with the single tip. Seven patients required at least one ECV due to mechanically induced VTs, all during mapping with the multispline catheter. The study protocol was terminated in eight patients (27%); in 4/8 because of two ECVs, in 2/8 because of VT requiring repeated ATP causing hemodynamic compromise, and in 2/8 because of excessive mechanical ectopy impairing catheter contact. All premature protocol terminations occurred while mapping with the Pentaray catheter. Conclusion Multi-spline catheters allow rapid substrate mapping but with substantial risk of mechanically induced arrhythmias compared to standard contact force sensing ablation catheters, requiring premature termination of substrate mapping because of safety concerns in 27% of the patients. Their use in post-MI VT ablation warrants careful risk–benefit assessment.