Ripple Mapping Guided Ablation of Ischaemic Ventricular Tachycardia.

Patients who have ischaemic heart disease and are at sufficient risk of, or have suffered, ventricular tachycardia may receive implantable cardioverter defibrillator (ICD) devices. ICD devices provide life-saving shocks to terminate ventricular tachycardia. There is however substantial evidence that correlates each life-saving shock with worsening prognosis.

Catheter ablation is a procedure that can treat the cause of ischaemic ventricular tachycardia (VT). Most catheter ablation procedures for ischaemic VT are performed in normal rhythm, with an end-point of arrhythmic substrate modification. Arrhythmic substrate modification refers to the process by which abnormal electrical activity in cardiac scar tissue (from ischaemic heart disease) is identified and treated by ablation.

Substrate modification catheter ablation procedures for ischaemic VT have been demonstrated to reduce ICD shocks and VT episodes in randomised trials compared to medications. However, ablation procedure outcomes are still imperfect with a recurrence rate of 50-60%.

Ripple Mapping is a method of mapping the hearts electrical signals, that may allow better identification of the abnormal activity within scar and so improve recurrence rates following ablation.

Patients referred for ablation of ischaemic VT, who have an ICD, will undergo their procedure with Ripple Mapping and subsequently followed up over a year, at 3 monthly intervals. The main assessed outcome will be ICD or VT events over a year. This will be compared to the number of ICD or VT events the year prior to ablation.

Inclusion criteria

• Patients with coronary artery disease and ischaemic cardiomyopathy requiring ICD implantation for primary or secondary prevention.
• Any episode of VT detected or treated appropriately (within monitor zone or therapy (ATP/shock) delivered) or by 12 lead ECG if the rate below the detection level of the device. An episode of VT will be defined as lasting more than 30 secs or a regular high rate episode meeting VT criterion for >50% of the time before the first therapy is delivered (i.e. VT degenerating into VF is acceptable under these circumstances).
• Ablation or medical therapy would be considered reasonable option for ongoing management.
• Males or females 18 - 80 years of age.
• Suitable candidate for catheter ablation.
• Signed informed consent.

Exclusion criteria

• Contraindication to catheter ablation.
• VT due to reversible causes.
• Severe valvular disease or ventricular thrombus.
• Active gastrointestinal bleeding.
• Serum Creatinine >200μmol/L or on dialysis.
• Active fever or infection.
• Life expectancy shorter than the duration of the trial.
• Allergy to contrast.
• Intractable heart failure (NYHA Class IV).
• Bleeding or clotting disorders or inability to receive heparin.
• Malignancy needing surgery, chemotherapy or radiotherapy.
• Pregnancy or women of child-bearing potential not using a highly effective method of contraception.
• Unable to attend follow-up visits or ICD clinics.