Grant: Operating Grant

Fainting affects about half of Canadians, is the cause of 1-2% of emergency room visits, and probably causes $250 million in health care spending each year. It is a particular problem for older people, because of their increased frailty and because it has several possible causes. One of these causes is intermittent heart block. The heart has 3 cables that conduct impulses from the pacemaker in the top of the heart to the pumping chambers in the bottom, and then the heart does not beat. This stops blood flowing to the brain, and people faint. Heart block occurs when all 3 cables fail to conduct at the same time. If this is seen, treatment is easy: insert a pacemaker. However doctors often only see that 2 of the 3 cables are missing on the patient's ECG. There are 2 ways to treat fainting in people who have ECGs that show 2 cables are missing: put a pacemaker in everyone, or insert a small ECG recorder under the skin, see what happens with the next faint, and then insert a pacemaker in those patients who have all 3 cables temporarily shorted out. No one knows which approach best balances risk and benefit. We will study 120 patients over 50 years old who have fainted recently, and who have ECG evidence of 2 cables missing. They will enroll in a randomized clinical trial, which is designed to give practical information to doctors and administrators. Consenting patients will be assigned randomly to receive either a pacemaker or an implantable ECG recorder, and we will follow them for 2 years. We then will compare the number of faints, the number of severe light headed spells associated with all 3 cables shorted out, and the number of complications related to the implanted devices, in each arm of the study. This is the only study of its kind in the world. It will have centres in Canada, Europe and South America. There is no "right" answer to the study; it will simply help us make sounder judgments in the care of Canadians.