Be your own advocate! Call and ask to schedule another ECG and if it reports the same ask to schedule an echo cardiogram. Your dr should already be starting that process unless it's something already known in your medical history, perhaps when you were very young. Either way, these are minor and non invasive procedures and will help pinpoint any issues so you can receive proper treatment if needed. Scarey as it may be, better to know so you can be relieved that there is nothing or start proper treatment so you can heal! DISCLAIMER: I am NOT a medical professional.
Was this an otherwise routine checkup, something you needed for a job, for example, or was the test done because you have been sick?
In any case, you should absolutely call the office back and tell them you are worried about these results and need to know if you have had a heart attack--and if so, what you should do next.
HOWEVER, do not freak out. You're young, so *if* you're otherwise healthy, and the "inferior infarct" business came from an EKG, there is a good chance this is an error called an 'artifact.'
Still, call the office back and try to sound scared. That will cause someone to review the results and explain things to you.