An infarct indictes a prior heart attack with heart muscle damage. The heart attack could have happened with no symptoms (silent heart attack), or you could have had symptoms but didn't associate it with a heart attack.
If you have had a prior heart attack, an echocardiogram test can identify the location (inferior...lower portion of the heart) and degree of heart muscle damage. The damage can impede heart wall movement and affect the heart's contractility so as to limit cardiac output.
The heart muscle damage can be permanent or dormant and heart cells can be revitalized with blood oxygen to an area that is not receiving sufficient blood flow. The underlying cause would/could be occluded coronary arteries....medication, stent, or bypass can open the occluded areas.
There are other causes such as heart valves regurgitation or stenosis, heart muscle disease causes by alcohol, drugs, medication, etc.