Factors that include age, disease, medical conditions and taking certain medications can cause a slow heart rate, known as bradycardia, according to WebMD. A slow heart rate is considered any rate lower than the typical heart rate of 60 to 100 beats per minute.
As a person ages, the electrical functions of the heart slow, often leading to slow heart rate, explains WebMD. Usually, this occurs in individuals over the age of 65. There are also diseases that slow the rate at which the heart beats, such as coronary artery disease, myocarditis, heart attack and endocarditis.
Conditions that slow the rate the heart beats are also a cause of bradycardia, states WebMD. These include hypothyroidism or an imbalance of the electrolytes in the body. Having too much potassium in the blood can also cause slowed heart rate. Medications that may slow the heart rate down are used to treat conditions such as high blood pressure or heart issues and include digoxin, antiarrhythmics and beta-blockers.
People who are in excellent physical condition, such as athletes and young, healthy adults, often have heart rates that are below 60 beats per minute. In this case, there is no problem with the heart, notes WebMD.