Heart attacks occur when the blood flow through the arteries to the heart is blocked for a long enough time to damage or kill a portion of heart muscle. Most heart attacks produce symptoms, such as severe crushing chest pain, nausea, shortness of breath, or a feeling of impending doom. Some people with heart attacks die immediately, before they are able to receive medical attention. Others are admitted to hospitals, where they typically receive several treatments to help prevent death and complications. Activities and conditions that can increase the risk for having a heart attack include a high-fat diet, smoking, a high cholesterol level, high blood pressure, diabetes, and kidney disease. After a heart attack, such factors as severe kidney failure and not getting appropriate treatment increase the risk for death. We do not know whether mild and moderate kidney disease increase the risk for death after a heart attack. We also do not know whether people with and without kidney disease receive the same types of treatments after heart attacks.