The RIPPLE AT-PLUS Study

Atrial tachycardia is a symptomatic arrhythmia, for which an effective treatment is a catheter ablation procedure. The goal of the Ripple AT-Plus study is to evaluate two methods of performing catheter ablation for atrial tachycardia. The main outcome assessed during the study is long-term recurrence of atrial tachycardia following the catheter ablation procedure.

Catheter based mapping of the electrical signals in the heart during atrial tachycardia can identify areas that require ablation in order to treat the arrhythmia. There are numerous methods by which to map atrial tachycardia. Isthmus guided ablation using Ripple Mapping is one such method, and has recently been demonstrated to improve diagnostic accuracy of mapping and therefore improve acute procedural outcomes (termination of the tachycardia). However, it is not known if improved acute procedural outcomes translate into long-term benefits for patients. At present, the recurrence rate following atrial tachycardia ablation is near 30%. We hypothesise that isthmus guided ablation using Ripple Mapping can reduce long-term recurrence following ablation as improved diagnostic accuracy of mapping can lead to more targeted, less extensive, ablation. Patients referred for catheter ablation of atrial tachycardia will be randomised to undergo the procedure by isthmus targeted approach using Ripple Mapping or conventional approach using local activation time. Otherwise, the catheters used to perform the mapping and ablation will be the same in both groups. After the procedure, follow up will occur at 1 year with a further Holter Montior. Any arrhythmia recurrence will be documented and the two arms will be compared for acute success, 12 month success, ablation required and procedure time.

Intervention: Isthmus targeted approach using Ripple Mapping catheter ablation of atrial tachycardia.

Ripple Mapping is used to map the atrial tachycardia mechanism. Using the scar thresholding technique the Ripple Map is interpreted and catheter ablation directed to the site of the heart identified as putative to the arrhythmia mechanism. All ablation lesions are confirmed to have conduction block across them using Ripple Mapping. This can include lesions created at previous ablation procedures.

Conventional activation mapping is used to map the atrial tachycardia mechanism. The resultant (activation) map is interpreted and ablation directed to the site of the heart identified as putative to the arrhythmia mechanism. All ablation lesions are confirmed to have conduction block across them using conventional mapping. This can include lesions created at previous ablation procedures.

Any confirmed episode of atrial arrhythmia (>30 seconds on Holter or 12 lead ECG) occurring in the 12 months after catheter ablation.

Atrial tachycardia termination (acute success) during ablation delivered to only target the diagnosed AT mechanism by the mapping approach used (first ablation set).

Entrainment not required to confirm or exclude the diagnosis made by 3D electroanatomic mapping methods.

Inability to terminate atrial tachycardia during the catheter ablation procedure, requiring external electrical cardioversion to achieve sinus rhythm.

Inclusion Criteria: Referred for catheter ablation of AT by the direct care team, based on clinical indication. Male or female, aged >18 years old. Able to consent for recruitment to the trial and the catheter ablation procedure. Exclusion Criteria: Contraindication to catheter ablation as deemed by the clinical team. Typical atrial flutter or AF on ECG.