Elimination of Ventricular Arrhythmia in Catecholaminergic Polymorphic Ventricular Tachycardia by Targeting “Catecholamine-Sensitive Area”: A Dominant-Subordinate Relationship between Origin Sites of Bidirectional Ventricular Premature Contractions

Electrophysiological Characteristics and Ablation Outcomes in Patients With Catecholaminergic Polymorphic Ventricular Tachycardia

BACKGROUND

Catheter ablation of premature ventricular contractions (PVCs) that trigger polymorphic ventricular tachycardia (PVT) or ventricular fibrillation has been reported as a novel therapy to reduce the syncope events in patients with catecholaminergic PVT, whereas the long-term ablation outcome and its value in improving exercise-induced ventricular arrhythmias remain unclear.

METHODS AND RESULTS

Fourteen consecutive selected patients with catecholaminergic PVT (mean±SD age, 16±6 years; 43% male patients) treated with maximum β-blockers with no possibility of adding flecainide were prospectively enrolled for catheter ablation. The primary end point was syncope recurrence, and the secondary end point was the reduction of the ventricular arrhythmia score during exercise testing. Twenty-six PVT/ventricular fibrillation-triggering PVCs were identified for ablation. The trigger beats arose from the left ventricle in 50% of the cases and from both ventricles in 36% of the cases. Purkinje potentials were observed at 27% of the targets. After a mean follow-up of 49 months after ablation, 8 (57%) patients were free from syncope recurrence. Ablation of trigger beat significantly reduced the syncope frequency (mean±SD, 4.3±1.6 to 0.5±0.8 events per year; P<0.001) and improved the ventricular arrhythmia scores at the 3-month (5 [range, 3-6] to 1.5 [range, 0-5]; P=0.002) and 12-month (5 [range, 3-6] to 2 [range, 0-5]; P=0.014) follow-ups. The induction of nontriggering PVCs postablation was closely associated with syncope recurrence (hazard ratio, 6.8 [95% CI, 1.3-35.5]; P=0.026).

CONCLUSIONS

Catheter ablation of PVT/ventricular fibrillation-triggering PVCs in patients with catecholaminergic PVT who cannot receive flecainide treatment seems to be a safe and feasible adjunctive treatment that may reduce the syncope burden and improve exercise-related ventricular arrhythmias. Induction of nontriggering PVCs after ablation is associated with a higher risk of syncope recurrence.

Identifying Premature Ventricular Complexes from Outflow Tracts Based on PVC Configuration: A Machine Learning Approach

BACKGROUND

Current inferences about the site of origin (SOO) of premature ventricular complexes (PVC) from the surface ECG have not been subjected to newer data analytic techniques that identify signals that are not recognized by visual inspection.

AIMS

The objective of this study was to apply data analytics to PVC characteristics.

METHODS

PVCs from 12-lead ECGs of a consecutive series of 338 individuals were examined by unsupervised machine learning cluster analysis, and indexes were compared to a composite criterion for SOO.

RESULTS

Data analytics found that V1S plus V2S ≤ 9.25 of the PVC had a LVOT origin (sensitivity 95.4%; specificity 97.5%). V1R + V2R + V3R > 15.0 (a RBBB configuration) likely had a LVOT origin. PVCs with V1S plus V2S > 12.75 (LBBB configuration) likely had a RVOT origin. PVC with V1S plus V2S > 14.25 (LBBB configuration) and all inferior leads positive likely had a RVOT origin.

CONCLUSION

Newer data analytic techniques provide a non-invasive approach to identifying PVC SOO, which should be useful for the clinician evaluating a 12-lead ECG.

[Ventricular arrhythmias in ion channel diseases]

In patients with ion channel disease the predominant arrhythmias are polymorphic ventricular tachycardias (VT), torsade de pointes tachycardia and ventricular fibrillation (VF). In only extremely rare cases is very rapid monomorphic ventricular tachycardia observed. This is why implantable cardioverter-defibrillators (ICDs) should always be programmed for treatment of VF only with high detection rates to avoid inappropriate discharges. In idiopathic VF and catecholaminergic polymorphic ventricular tachycardia (CPVT), no baseline electrocardiographic abnormalities can be detected, whereas in Brugada syndrome, long QT syndrome, early repolarisation syndrome and Anderson-Tawil syndrome alterations of the baseline ECG are very important to identify patients at risk.