There is no doubt they have improved quality of life and survival for millions of patients. Complications, such as movement of the pacemaker wire within the heart, infection around the pacemaker and component failure are uncommon but do occur in about 5 per cent of patients. It was widely believed that because of this abnormal sequence, single chamber pacing was the cause of a variety of symptoms such as palpitations, fatigue, shortness of breath and lightheadedness, sometimes known as the pacemaker syndrome. The development of a pacemaker that could pace both upper and lower chambers and maintain a more normal sequence of heart beating occurred about 15 years ago. Dual chamber pacing became increasingly popular when uncontrolled studies were reported which indicated that the dual chamber pacemaker patients seemed to be living longer and to be having a lower frequency of stroke, heart failure and abnormal heart rhythm known as atrial fibrillation.
Atrial fibrillation can cause annoying palpitations and is associated with a risk of stroke.
Today this stroke risk is managed by the use of blood thinning medications that are quite effective. There has been a marked trend in North America and Europe to use dual chamber pacemakers instead of single chamber ones. However, there is no strong evidence that dual chamber pacemakers are actually superior to single chamber, and they are more expensive and complex to use. Canadian clinical scientists decided to properly test the hypothesis that dual chamber pacemakers are superior to single chamber by means of a large randomized controlled clinical trial. This study was funded by the Medical Research Council of Canada and was performed between 1992 and 1998.