Could it be right that people who have experienced cardiac arrest don't survive very long?

Yes.: Survival after cardiac arrest is related to the underlying cause of the arrest (myocardial infarction, hypothermia, toxin, etc), the time from the arrest and treatment, the underlying health of the individual, and even where the arrest occurred (such as in hospital or out of hospital). Because cardiac arrest mean a lack of blood flow to the body, survival may be limited in many patients.