From The Merck Manuals Online Medical Library-Home edition for patients and caregivers

Cardiac rehabilitation may be useful for some people who have had a recent heart attack, a sudden onset or worsening of heart failure, or cardiac surgery. The goal is to maintain or regain independence, at least with activities of daily living, within the constraints of abnormal heart function.

Remaining in bed for longer than 2 or 3 days can lead to deconditioning and even depression. Therefore, cardiac rehabilitation is started as soon as medical care for an event such as a heart attack has been stabilized, usually while the person is still in the hospital. Rehabilitation programs typically begin with light activity, such as transferring to and sitting in a chair. When these activities can be performed comfortably, usually by the second or third day, more moderate activities, such as dressing, grooming, and walking short distances, are begun. If fatigue or discomfort occurs as a person increases his activity (for example, walking the length of the hall), the person is instructed to stop immediately and rest until symptoms disappear. The doctor then reassess the person's readiness to continue rehabilitation.

After discharge, the amount and intensity of activity is slowly increased, and a full range of normal activities can be resumed after about 6 weeks. However, most people benefit from an outpatient cardiac rehabilitation program, which is usually about 12 weeks long, because of the instruction and monitoring they receive. Cardiac rehabilitation programs include help with handling the psychologic effects of having had a heart attack or heart surgery. They also include instruction about why changes in lifestyle are necessary and how to make them—so that risk factors are modified. Quitting smoking, losing weight, controlling blood pressure, reducing blood cholesterol levels through diet or drugs, and performing daily aerobic exercises all help prevent or slow the progression of coronary artery disease and reduce the risk of another heart attack. Similarly, modification of risk factors may help slow the progression of heart failure.