What would happen to a patient who has cardiac arrest while undergoing chemotherapy?

Depends: Cardiac arrest is never a good thing. What happens following depends on several things. What was the cause? How fast was the heart restarted and was CPR good? What is their overall health like? Any residual effects from the arrest? These answers to these questions and more can help predict the outcome.

Chemo and heart: It depends upon several factors. First, what caused the arrest. What effects did it have on the patient. If the arrest was part of an allergic reaction to the chemotherapy, many reports have shown it is safe to give the patient the same chemotherapy through a desensitization regimen.