Catheter Ablation versus Anti-arrhythmic Drugs for Premature Ventricular Complexes (CAAD-PVC)

Patients randomised to the intervention arm will be allocated to undergo the catheter ablation (CA) procedure, performed by a specialist cardiologist/electrophysiologist. This procedure typically lasts 2-4 hours and may be performed with the patient under sedation or general anesthesia, depending on the complexity of the patient. Patients will typically present to hospital the day of their porcdure and stay overnight following completion of the procedure. Patients randomised to the intervention arm will be expected to have the CA procedure within 6 weeks post randomisation. Medical therapy can be used as a temporising measure before CA, as is standard of care. If the patient is drug naïve, initiation of sotalol is recommended, but not mandated, as per the control arm. Post ablation, all PVC medial therapy should be discontinued. Halting medical therapy for PVCs before a CA is standard practice: for patients already medicated for PVCs prior to CA, an additional multiday heart rhythm monitor may be performed after at least one week or 5 half-lives without any medical therapy to establish baseline burden. CA procedures will be performed in the standard fashion, as accepted by international guidelines. Procedures will be performed under conscious sedation or general anaesthesia, The CA procedure requires venous and/or arterial femoral vascular access for the advancement electrode catheters to the coronary sinus, right ventricle and/or the left ventricle to aid identification of PVC site of origin. If the PVCs are arising from the left ventricle, access will be obtained via either transeptal puncture or retrograde aortic access at the operator's discretion. Where available, pre-procedural imaging with cardiac MRI or cardiac CT will be integrated with the electroanatomic mapping system to aid procedures. Intracardiac echocardiography will be encouraged but not mandated. Ablation will be guided by a combination of standard mapping techniques, as per standard practice. Preference will be given to “activation mapping” of the PVCs (which may be stimulated by administration of intravenous isoprenaline) using a three-dimensional electroanatomic mapping system. If there is paucity of PVCs, then “pace-mapping” will be performed. End point of ablation will be abolition of all PVCs (with and without isoprenaline provocation) with a 30-minute waiting period. Induction of ventricular tachycardia (VT) with programmed electrical stimulation (PES) will also be attempted during the procedure, as a standard practice to aid risk patient risk stratification. PES will be performed from the right ventricular apex, using a well validated stimulation protocol. A drive train of 400 ms will be used with each extra-stimulus introduced at 300 ms and decremented by 10ms until ventricular refractoriness. An additional extra-stimulus will then be added until all 4 extra-stimuli are refractory. PES will be accompanied by burst ventricular pacing and repeated with and without administration of isoprenaline. Intravenous heparin will be given at the beginning (bolus) and during the procedure, especially if endocardial left ventricular access is planned to prevent risk of systemic and/or venous thromboembolism. Further heparin boluses are given to maintain an ACT >300s, as per published guidelines. If the patient is on anticoagulation, the procedure may be performed on uninterrupted warfarin and/or dabigatran, or bridging therapy with intravenous heparin or subcutaneous enoxaparin, as per the operator discretion. Post procedural anticoagulation for 6 weeks is recommended, but not mandated, if extensive ablation (RF time =10 minutes) is performed. Post procedure, medical therapy (if patient was receiving it) is stopped. Repeat ablation procedures will be discouraged for the 6 months of monitoring. Occasionally, patients may experience a random episode of PVC quiescence, leading to an absence of PVCs on the day of CA. This can be a result of changes in medication, stress, hormones, electrolytes and can be unpredictable. As at least one PVC occurring with the patient in the procedural area is required to perform a CA, an episode of PVC quiescence on the day of the procedure that inhibits the ablation from taking place will not preclude the patient from having a repeat attempt at the CA. Procedural reports, medical notes and admission records will bu used to monitor adherence to the intervention.