New York Heart Association (NYHA) functional class for patients with cardiac disease and ability index of Somerville
| Somerville index | |
| 1 | Normal life: full time work or school, pregnancy manageable. |
| 2 | Able to work (part time): interference with life (socio/community imposition). |
| 3 | Unable to work: limitations on all activities, pregnancy risk. |
| 4 | Extreme limitation: dependent, almost housebound. |
| NYHA classes | |
| I | No limitations of physical activities. Ordinary activity does not cause undue anginal pain, dyspnoea, fatigue, or palpitations. |
| II | Slight limitations of physical activities. Comfortable at rest, but ordinary activity results in anginal pain, dyspnoea, fatigue, or palpitations. |
| III | Marked limitations of physical activities. Comfortable at rest, less than ordinary activity causes anginal pain, dyspnoea, fatigue, or palpitations. |
| IV | Unable to carry on any physical activities without discomfort. Symptoms of cardiac insufficiency or anginal syndrome may be present even at rest. If any physical activity is undertaken discomfort is increased. |