High blood pressure means the pressure inside the blood vessels (called arteries) is too high. As the heart pumps against this pressure, it must work harder. Over time, this causes the heart muscle to thicken.
Without treatment, symptoms of heart failure may develop. Sometimes, the muscle can be so thick that it does not get enough oxygen. This can cause angina (chest pain).
High blood pressure also leads to thickening of the blood vessel walls. When combined with cholesterol deposits in the blood vessels, the risk of heart attack and stroke increases.
Hypertensive heart disease is the leading cause of illness and death from high blood pressure.