Project 461536

Pacemakers are life-saving devices for patients who develop very slow heart rates. If a patient is completely dependent on the pacemaker without electrical signals of their own, they can develop a weak heart muscle. Up to 25% of patients will develop heart failure because they are completely dependent on the pacemaker. Once heart failure develops, patients have a reduced quality of life, and they are much more likely to present to the hospital with water on their lungs. Studies have shown a much higher rate of hospitalization and death in these patients. Our aim is to prevent heart failure due to too much pacing in the heart's lower chamber (right ventricle). Instead of implanting a regular pacemaker for patients who present with extreme slowing of the heart, we hypothesize that through a new pacing strategy called "Left bundle branch pacing (LBBP)" we can prevent weakening of the heart by recreating the heart's natural electricity. LBBP uses the same simple pacemaker, but the lower (ventricular) wire is placed directly within the muscular wall separating the two ventricles, at a critical electrical region. We will perform a trial that compares two pacing strategies: A) Standard right ventricular pacing (control group) vs B) Left bundle branch pacing (LBBP) (experimental group). All patients presenting with heart block requiring an urgent pacemaker will be candidates for the trial as long as their heart function is mildly weakened at baseline. The patients will have routine follow-up in the pacemaker clinic. We will compare the control and experimental patient groups to see whether LBBP will prevent weakening of the heart muscle. Due to the expertise required to perform LBBP, only very experienced electrophysiologists across Canada have been selected to participate in the trial. These cardiologists specializing in electrical abnormalities of the heart have undergone specific training to perform LBBP safely and effectively.