Can dental pain shots be life-threatening?

Possible: It is possible as with all drugs, however it is very rare.

Not usually: There is special anesthetic for heart pt's otherwiise, unless you get an overdose, it's very safe.

Possibly: I assume you are referring to local anesthesia. If so, then yes there is a risk just as there is with any medication that you take. Although minimal, there is the chance of an allergic reaction and that's why it is important to give a complete and accurate medical history.

Yes: Yes dental anesthesia can cause problems. Some patients have an Epinephrine reaction and it is important to tell your dentist if you have any medical issues such as heart problems or blood pressure issues. They can use an alternative which will not cause heart racing (tachycardia). Full disclosure of diseases, allergies, implants, and medical conditions is essential to a patients well being.

Driving: Much less of life threatening risk than driving.