Ischemia is a (deficency) in supplying oxygenated blood to heart cells due to functional constriction or actual obstruction of the vessels. Often there is angina (chest pain) associated with the condition but not always. Constriction can be a spasm, tortuous malformed vessesls, and obstruction can be due to a buildup of plaque or a blood clot.
Myocardial infarction (MI) is an acute obstruction (ie blood clot, etc.) of vessel blood flow to cause cell necrosis (death), but there is a window of opportunity of a few hours to provide oxygen to heart cells that are only stunned and can sometimes be revitalized..
Ischaemic is inability to provide oxygen to the heart muscle and the heart muscle is damaged because of the lack of oxygen. Myocardial infarction is a heart attack.