Anemia may be caused by a variety of factors, including a lack of iron, a lack of vitamin B-12, certain prescription drugs (e.g., antibiotics or medications to treat AIDS), antacids, radiation therapy, chemotherapy, pregnancy, heavy menstrual flow or other bleeding, and certain chronic medical conditions. Although most cases of anemia can be cured with treatment, some cases are due to medical conditions that cannot be changed (e.g., sickle cell anemia, thalassemia).

Severe cases of anemia have been associated with a number of heart conditions, including:

• Heart failure. Many heart failure patients also have anemia, which tends to worsen as the heart failure progresses. Studies indicate that treating anemia in heart failure patients can significantly improve heart function and reduce the number of hospitalizations. Furthermore, in some cases severe anemia can actually cause heart failure because it forces the heart to work harder in order to circulate a lower number of red blood cells throughout the body.
  
  
• Cardiomyopathy or enlarged heart. Because severe cases of anemia can cause the heart to work harder, the condition can lead to an enlargement of the entire heart or heart muscle. Over time, cardiomyopathy can develop into heart failure.
  
  
• Bacterial endocarditis. Mild anemia may be detected in patients who have this infection of the lining of the heart and heart valves.
  
  
  
  
• Cancer of the heart. Although rare, anemia may be associated with a tumor in either of the upper chambers of the heart (atria).

Studies have indicated that individuals with anemia may have a 40 percent greater risk of having a heart attack, developing heart disease or needing a procedure to clean the arteries than those without the blood disorder.

Anemia may also increase risks for patients undergoing heart surgery, especially older patients. When present for more than two days after heart surgery, anemia has also been associated with an increased risk of complications or even death in older people.