There can be. The process of CPR can sometimes cause broken ribs or internal bleeding. Anyone who is successfully revived will remain unwell and need more treatment, usually in a specialist coronary care or intensive care unit. If you have a cardiopulmonary arrest with a pre-existing medical problem it is unlikely you will make a full recovery. In general, most people never recover to the same level of physical or mental health as before a cardiopulmonary arrest.