Heart attack
When one experiences a heart attack, the heart is deprived of oxygen since the blood supply that generally nourishes the heart is cut off. And the heart muscle [4] begins to die. It goes both ways that a heart attack could cause bradycardia, and bradycardia could also cause a heart attack.
Congestive cardiomyopathy
The heart muscle could also suffer from a progressive disease known as cardiomyopathy. Congestive cardiomyopathy is when the heart muscle weakens and is unable to pump blood to other parts of the body as well as it should. Congestive cardiomyopathy could be the cause of bradycardia.