If your heart stops pumping enough blood suddenly – such as what happens during a heart attack, when a larger part of the heart muscle tissue dies – then it is considered to be “acute” heart failure and is a medical emergency.
By contrast, chronic heart failure develops over a longer period of time. It may go unnoticed at first. But if the heart’s performance continues to decrease, it will lead to noticeable symptoms sooner or later.
Doctors assess how advanced heart failure is based on its severity:
- Symptom-free (asymptomatic) heart failure does not yet cause any symptoms. Certain tests like echocardiography can detect that the heart isn't performing as well as it should.
- Mild heart failure: causes symptoms like exhaustion or shortness of breath during more strenuous physical exercise like climbing stairs or walking uphill. But light physical exertion is possible without any symptoms.
- Moderate heart failure causes symptoms even during everyday activities and light physical exercise, like walking on a level surface.
- Severe heart failure causes symptoms at rest or during even the slightest physical exercise. Some people with severe heart failure are bedridden.
Doctors also consider how well the heart fills with blood and how much blood the heart’s left ventricle pumps per beat.
The way in which heart failure continues to develop over time depends on things like what is causing it and whether you have other medical problems. In some people the symptoms can be kept under control for many years, the progression of the disease can be slowed down, the symptoms can be improved and life expectancy can be increased. But sometimes the heart becomes weaker after a short amount of time.
If another treatable medical problem (e.g. damaged heart valves or high blood pressure) is responsible for the heart failure, it is sometimes possible to stop the heart failure from getting worse or have it go away by treating the cause.
In most people, though, the cause of heart failure can't be treated, and the heart becomes weaker over time.