A decreased cardiac muscle contraction will result in a reduced cardiac output which means there will be less oxygenated blood that will circulate through the body. This will cause the supply of the energy is limited. When the demand of energy is increased, like when doing exercise or walking upstairs, the energy might be not enough. This can cause the elder to feel easily fatigue. Chest pain is also common as the heart could also not getting enough blood.
Decreased cardiac output also can cause lower blood pressure, make the elder be at risk of postural hypotension. The symptoms would be feeling dizzy if going stand right after wake up. Don't go stand after wake up. Try to sit down a moment instead so the blood pressure will not decrease too much.