Background: Electrical storm (ES) is defined by clustering episodes of ventricular tachycardia (VT) and is associated with severe long-term outcomes. We sought to evaluate the prognostic impact of radiofrequency catheter ablation (RFCA) in ES as assessed by aggressive programmed ventricular stimulation (PVS). Methods: Single-center retrospective longitudinal study with 82 consecutive ES patients referred for RFCA with a median follow-up (IQR 25–75%) of 45.43 months (15–69.86). All-cause mortality and VT recurrences were assessed in relation to RFCA outcomes defined by 4-extrastimuli PVS: Class 1—no ventricular arrhythmia; Class 2—no sustained monomorphic VTs (mVT) inducible, but non-sustained mVTs, polymorphic VTs, or VF inducible; Class 3—clinical VT non-inducible, other sustained mVTs inducible; and Class 4—clinical VT inducible. Results: Class 1, Class 2, Class 3, and Class 4 were achieved in 56.1%, 13.4%, 23.2%, and 7.4% of cases, respectively. The combined outcome of Class 1 + Class 2 (no sustained monomorphic VT inducible) led to improved survival (log-rank p < 0.001) and reduced VT recurrence (log-rank p < 0.001). Residual monomorphic VT inducibility (HR 6.262 (95% CI: 2.165–18.108, p = 0.001), NYHA IV heart failure symptoms (HR 20.519 (95% CI: 1.623–259.345), p = 0.02)), and age (HR 1.009 (95% CI: 1.041–1.160), p = 0.001)) independently predicted death during follow-up. LVEF was not predictive of death (HR 1.003 (95% CI: 0.946–1.063) or recurrences (HR 0.988 (95% CI: 0.955–1.021)). Conclusions: Non-inducibility for sustained mVTs after aggressive PVS post-RFCA leads to improved survival in ES, independently of LVEF.

Introduction: We report the case of a 41-year-old female with documented narrow QRS tachycardia. During electrophysiological study, both orthodromic and antidromic atrioventricular reentry tachycardia (AVRT) were demonstrated as well as short episodes of pre-excited atrial fibrillation. Programmed atrial stimulation resulted in decremental anterograde conduction on the AP, thus confirming an unexpected Mahaim accessory pathway (AP) diagnosis. Discussion: Limited 3D activation maps of the right atrium during orthoAVRT, respectively, and the right ventricle (RV) during antiAVRT were constructed and helped accurately describe the atrial and ventricular insertion points, which were superposed on the tricuspid ring, confirming the existence of a single short atrio-ventricular right free wall AP. Short atrioventricular APs with anterograde Mahaim-type conduction concomitantly sustaining orthodromic AVRT are extremely rare. Conclusions: Electroanatomical 3D mapping may help both to clarify the diagnosis and increase the success rate by accurately describing the insertion points of complex accessory pathways.

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Funding Acknowledgements Type of funding sources: None. Background/Introduction Outcomes in post-myocardial infarction (MI) patients which are referred for catheter ablation (CA) for drug-refractory electrical storm (ES) are influenced both by patient characteristics and procedural results. Previous data has shown higher risk for the first incident ES episode in the presence of non-revascularized chronic total occlusions (nCTOs). However, the prognostic effect of nCTOs in post-ES ablation patients is relatively unknown. Purpose We evaluated the impact of the presence of nCTO on all-cause mortality and sustained VT recurrence rate after CA for ES in post-MI patients. Methods In this single centre retrospective longitudinal study, we included consecutive post-MI patients referred for CA for drug-refractory ES. The median follow-up interval was 34.36 (7.25-63.65) months. CA outcome was defined by the absence or presence of residual sustained monomorphic VT at end-procedural programmed ventricular stimulation (PVS). Coronary angiography was performed prior to ablation in all patients. Results Sixty-four patients were included (85.9% (n = 55) males, age 62.64 ± 11.13 years). The mean left ventricular ejection fraction (LVEF) was 31.41 ± 10.99. There were 18.8% (n = 12) patients with nCTOs. Residual sustained monomorphic VT inducibility was documented in 28.1% (n = 18) cases. There were 29.7% (n = 19) deaths and sustained VT recurrences, respectively, during the monitored interval. Nine out of twelve (75%) nCTO patients died during follow-up. The presence of a nCTO induced a borderline significant higher risk of sustained VT recurrence during follow-up (HR 2.527, CI.95% 0.992 – 6.435, p = 0.052) in univariable Cox regression. In addition to age and residual sustained monomorphic VT at PVS, a multivariable Cox regression model identified the presence of nCTO as an independent predictor for all-cause mortality (HR 3.194, CI 95% 1.212-8.420, p = 0.019) (Figure 1). Conclusion(s) The presence of a nCTO in post-MI patients may be associated with higher all-cause mortality and sustained VT recurrences after ablation for drug-refractory electrical storm.