There are significant risks from this procedure. If your doctors recommend electrophysiologic testing, they feel that this is a risk worth taking because it will allow them to take better care of you in the future. Because you are right in the lab and attached to a monitor while you undergo the rhythm changes, it is easier than ever for them to treat you should your arrhythmia occur and cause you symptoms.
Complications are rare, but new rhythm changes can occur.
A very rare complication occurs if the ablation instrument burns a hole through the heart muscle. This results in bleeding and may require immediate surgery. There are some more minor risks from the test. Among them is bleeding from the place that the catheter was inserted. A few people are allergic to the medicines used in the procedure and this can cause a rash or other symptoms.