You don't have the symptoms of heart failure. With that aside, conditions or medicines that slow the passing of electrical signals through the heart but are not the result of heart damage. These conditions include:
Hypothyroidism (underactive thyroid gland), electrolyte imbalances, such as abnormal blood levels of potassium. .
Heart medicines, such as beta-blockers, calcium channel blockers, antiarrhythmics, and digoxin can slow the heart rate.