Catheter ablation of haemodynamically unstable or non-sustained ventricular tachycardia

BACKGROUND: Ventricular tachycardia (VT) may be haemodynamically unstable or non-sustained, interfering with detailed activation mapping. Non-contact mapping permits beat-by-beat analysis of VT, projected upon a 3-dimensional reconstructed geometry of the cardiac chamber. Objective - The aim of the present study is to determine the utility of non-contact endocardial mapping to guide ablation of haemodynamically unstable VT or non-sustained VT. METHODS AND RESULTS: Eighteen VTs in 17 patients were induced (cycle length 336 +/- 58 ms) and mapped. Three patients were mapped during premature ventricular complexes (PVCs) because sustained VT could not be induced. Analysis of the archived non-contact activation maps was performed to identify the exit point and/or the diastolic pathway of theVT reentry circuit.The endocardial exit points (10 +/- 16 ms before QRS) were defined in 17/18 VTs (94%). A diastolic pathway was identified in 5/6 ischaemic VTs.The earliest activation sites were identified in all 3 patients with PVCs. Radiofrequency current was applied around the exit point or to create a line of block across the diastolic pathway. Catheter ablation was performed in 17/18 VTs, including 3 patients mapped using only PVCs. Ablation was successful in 16/18 VTs (89%) and in 1 5/17 patients (82%). Catheter ablation was not performed in one patient (peri-hisian VT) and was unsuccessful in one patient (mapped during PVCs). CONCLUSIONS: Non-contact endocardial mapping is useful to guide radiofrequency catheter ablation of untolerated or non-sustained VTs.