What are the causes of heart failure?

In most cases heart failure is caused by another health problem. Some of these problems damage the heart muscle, so the heart isn’t able to pump as well as it should. Other problems make the heart work harder, which can weaken the heart by tiring it out.

Coronary artery disease (CAD) is the most common cause of heart failure. The coronary arteries are the small blood vessels that supply blood and oxygen to the heart muscle. CAD is caused by atherosclerosis (also called “hardening of the arteries”). This condition occurs when plaque (deposits of fat or cholesterol) accumulates on the inner surface of the arteries. As plaque builds up the coronary arteries may become 

narrowed, and this reduces blood flow to the heart muscle (Figure 13). As a result the heart muscle that is deprived of oxygen-rich blood cannot work normally. The muscle can weaken, and heart failure may develop.

A heart attack can occur when the narrowing in a coronary artery progresses to the point where a part of or the entire artery is blocked. This is known as a myocardial infarction. This blockage can stop blood flow to a part of the heart muscle. Without the oxygen-rich blood, this part of the heart muscle may become permanently damaged. The damaged portion of the heart muscle loses its ability to pump, and scar tissue may develop. Therefore after a heart attack, the rest of the heart muscle must work harder. Over time, the strained heart muscle may weaken further, and heart failure can develop.

Blood pressure is a measure of how hard blood pushes against the artery walls. A normal blood pressure should be less than 130/80 mm Hg. High blood pressure (also called hypertension) is when blood is pushing harder than normal. This makes your heart work harder. As a result, over time the chambers of your heart may enlarge or may become abnormally thickened. Ultimately, if the high blood pressure is not controlled, the heart muscle becomes less efficient, and may stretch and weaken. This may lead to heart failure.

Valve disease occurs when the valves between the heart chambers do not open or close properly. If a heart valve becomes narrowed (known as “valve stenosis”), it does not open fully, and your heart has to work harder to pump the blood forward to your body. If a valve does not close tightly, blood leaks backward (referred to as “valve regurgitation”), forcing your heart to pump some of the same blood back through the same valve again. This backflow creates extra work for the heart and can weaken it. Over time, this can possibly lead to heart failure symptoms.

A cardiomyopathy is a weakening of the heart muscle. This is described in detail in Question 63. The dilated, weakened heart muscle cannot pump efficiently, and this can cause heart failure to occur.

 Other health problems can strain the heart and make it more likely to weaken. Diabetes makes coronary artery disease and heart failure more likely. Heart failure may occur more commonly if you have abnormal thyroid function or a low blood count (“anemia”). Chronic kidney problems can affect how well your body handles its electrolytes and can lead to water retention, which may worsen symptoms of heart failure.