The American Heart Association and American College of Cardiology recommend that everyone with heart disease have a flu shot. Flu can cause the symptoms of heart disease to worsen, sometimes leading to heart failure. Flu also can cause pneumonia. People with cardiovascular disease are more likely to die from flu than people with any other chronic condition. In a randomized trial, 301 patients hospitalized for heart attack or angioplasty received flu shots or remained unvaccinated. Over the following year, 23 percent of unvaccinated patients died of heart disease or had a non-fatal heart attack, compared with only 11 percent of vaccinated patients.