Ventricular Tachycardia (VT) Ablation or Escalated Drug Therapy
Ventricular Tachycardia Ablation or Escalated aNtiarrhythmic Drugs in ISchemic Heart Disease
This study will compare aggressive antiarrhythmic therapy to catheter ablation for ventricular tachycardia in patients who have suffered prior myocardial infarction. The purpose of this study is to evaluate the optimal management of patients presenting with recurrent VT and receiving ICD therapy in spite of first-line antiarrhythmic drug therapy. The hypothesis is catheter ablation is superior to aggressive antiarrhythmic drug therapy for recurrent VT.
This is a multicentre, parallel group, two arm, unblinded, randomized clinical trial to compare two management strategies for patients with ischemic heart disease and recurrent ICD therapy despite at least one antiarrhythmic drug. The primary endpoint will be a composite of appropriate ICD shocks or death.
Intracardiac electrode catheters are placed via central vasculature to identify myocardial scar, and surviving conduction channels within the scar which form the substrate for ventricular tachycardia. Radiofrequency energy is applied to these sites, interrupting the VT circuits.
Patients who have 'failed' antiarrhythmic therapy (except amiodarone) will be prescribed: Amiodarone 400 mg twice daily for 2 weeks, followed by 400 mg/day for 4 weeks, followed by 200 mg/day thereafter. Patients who 'failed' amiodarone (less than 300mg/day) will be prescribed: Amiodarone 400 mg three times a day for 2 weeks, followed by 400 mg/day for 1 week and 300 mg/day thereafter. Patients who 'failed' amiodarone (greater or equal to 300mg/day) will be prescribed: Amiodarone at the current dose with the addition of mexiletine 400 to 800 mg/day
Catheter ablation for Ventricular tachycardia will be performed within 14 days of randomization.
Patients are prescribed a loading dose of amiodarone or the addition of mexiletine to their current anti-arrhythmic medication which is stratified by the dose and type of antiarrhymic medication at the time of the index arrhythmic event.
Inclusion Criteria: Prior Myocardial Infarction An implantable defibrillator One of the following VT events (within the past 3 months): greater than or equal to 3 episodes of symptomatic VT treated with ATP greater than or equal to 1 appropriate ICD shock greater than or equal to 3 VT episodes within 24 hours sustained VT below detection rate of the ICD documented by ECG "Failed" first-line antiarrhythmic drug therapy as defined by one of: Appropriate ICD therapy or sustained VT occurred while patient was taking amiodarone (stable dose >/= 2 weeks) Appropriate ICD therapy or sustained VT occurred on another antiarrhythmic drug (stable dose >/= 2 weeks) Exclusion Criteria: Active ischemia (acute thrombus, dynamic ST elevation on ECG) or another reversible cause of VT (eg. electrolyte abnormalities, drug induced arrhythmia) Are known to be ineligible to take amiodarone (eg. active hepatitis, current hyperthyroidism, pulmonary fibrosis, known allergy) Are ineligible for ablation (left ventricular thrombus, implanted mechanical aortic and mitral valves) Renal Failure (creatinine clearance < 15 ml/min) Current NYHA functional class IV heart failure or CCS Functional Class IV angina Recent ST elevation myocardial infarction (< 1 month) Recent coronary bypass surgery (< 3 mon) or recent PCI (< 1 mon) Pregnant prior ablation for ventricular tachycardia A systemic illness likely to limit survival to < 1 year Unable or unwilling to provide informed consent