Grant: Operating Grant

Atrial fibrillation (AF) is the most common heart rhythm disorder. It affects quality of life and increases the risk of stroke and death. Its name comes from the fibrillating (i.e. quivering) of the two upper chambers (atrium) of the heart instead of a coordinated contraction, causing a rapid, irregular heart rate. Despite advances in drug treatment, AF remains uncontrolled in many patients. In most cases, abnormal electrical impulses that set off AF come from the pulmonary veins. The pulmonary veins carry blood from the lungs to the left upper chamber (atrium) of the heart. Catheter ablation, a procedure used to remove faulty electrical pathways, has been developed to cure AF. The procedure involves placing catheters (flexible wires) through veins in the groin. The catheters are advanced towards the heart, into the left atrium. Then, electric energy is used to ablate (destroy) the atrial tissue around the pulmonary veins which is responsible for AF. Unfortunately, the abnormal electric impulses in this tissue can reappear following the ablation in up to 50% of cases and then the procedure must be repeated. Adenosine is a commonly used intravenous drug whose effect lasts seconds. This drug can identify areas of the atrium that need additional ablation. Adenosine-guided ablation is not used routinely. We propose a study to see whether adenosine-guided ablation is better than standard ablation in patients with AF. In this study, adenosine will be given to all patients. If the drug reveals that additional areas of abnormal electrical impulses still exist, half the patients will have their ablation performed as usual, while the other half will have more tissue ablated. A total of 526 patients will be included in this study in 19 clinical centres throughout Canada, Europe and Australia. If our study shows that the adenosine-guided ablation is better than standard ablation, it will become standard of care and we could avoid having to repeat procedures in our patients.