I lied at MEPS. Will they go back and look through my medical records?

I lied about my heart murmur in 1975. Doctor at AFEES (MEPS now) didn't catch it.
They DID after I passed out after an 18 hour shift in the mess hall in Boot Camp.
Navy doctor asked how bad I wanted to stay in---Told them I couldn't go home and tell my WW2 Sailor father I didn't make it. So he said "You can stay".
Sure didn't keep me out of Marine Infantry as an FMF Corpsman. Neither did my plus 4 flat feet.

I will say it is not a good way to start off a military career to break one of the core values of the of all the branches, "Integrity". That being said, you are not first and you won't be the last. Some have even lied about smoking pot a few times. Not saying who, but let's just say that even that simple lie can stick with you and you think about it even decades later not because of what was done, but because it was lied about.
Now in your situation, would your medical condition put yours or others lives at risk? If so, than that is a pretty serious lie and you should probably be separated for it or disqualified for enlisting. If it is something that would not put others lives at risk, then i say it is still a lie but something that can be forgiven if you fess up, but don't lie again. Truth always has a way of coming out. You definitely want to be the one to tell the truth and not let other find the truth before you tell them. It erodes the trust people have in you. I am hoping that who ever makes the decision about your future can chalk it up you being really eager to enlist. That is something to proud of. Just don't taint what I assume to be noble intentions with a lie like this.
Good luck to you, I hope this works out and you take this lesson with you on your hopefully honorable military service.

I will say it is not a good way to start off a military career to break one of the core values of the of all the branches, "Integrity". That being said, you are not first and you won't be the last. Some have even lied about smoking pot a few times. Not saying who, but let's just say that even that simple lie can stick with you and you think about it even decades later not because of what was done, but because it was lied about.
Now in your situation, would your medical condition put yours or others lives at risk? If so, than that is a pretty serious lie and you should probably be separated for it or disqualified for enlisting. If it is something that would not put others lives at risk, then i say it is still a lie but something that can be forgiven if you fess up, but don't lie again. Truth always has a way of coming out. You definitely want to be the one to tell the truth and not let other find the truth before you tell them. It erodes the trust people have in you. I am hoping that who ever makes the decision about your future can chalk it up you being really eager to enlist. That is something to proud of. Just don't taint what I assume to be noble intentions with a lie like this.
Good luck to you, I hope this works out and you take this lesson with you on your hopefully honorable military service.

You here now...go be great

It's hard to say but if you knowingly lied on your enlistment paperwork you could be rejected based on the condition, you could be rejected out of hand for a fraudulent enlistment, or you could be accepted on the condition that it does not develop into an issue during basic training. There may be trust issues with your leadership however. In any case you were flat wrong to lie.

John, We all have goals and desire but you lying about a heart condition is the most selfish thing you can do. You’re thinking about “you”, but once you join the brotherhood lives depend on you. Be a man and put your cards on the table, being all you can be doesn’t mean lying for personal vanity. Remember, you lie, men die.

No one has ever lied at meps before. You're the first person to ever do so. Let us know what happens so we may help those in the future that do so out.

I am an American Soldier.
I am a Warrior and a member of a team.
I serve the people of the United States, and live the Army Values.
I will always place the mission first.
I will never accept defeat.
I will never quit.
I will never leave a fallen comrade.
I am disciplined, physically and mentally tough, trained and proficient in my warrior tasks and drills.
I always maintain my arms, my equipment and myself.
I am an expert and I am a professional.
I stand ready to deploy, engage, and destroy the enemies of the United States of America, in close combat.
I am a guardian of freedom and the American way of life.
I am an American Soldier.

First off you didn't lie. You told MEPS what you were told at a younger age. It sounds like MEPS is sending you to the Cardiologist because of what you said and what they found. Get a copy of the written and signed results of the doctor's visit and hand deliver it to MEPS even if the doctor's office said they will send it to them. Also make a copy for your records. MEPS will make the determination since they are the ones sending you to the Cardiologist.

Oof. Considering that your name is out there now there is a potential risk. It wouldn't have been if you hadn't said anything. The O-5's and E-9's of the world will make a gigantic deal of this on here as it is in their nature to do so and they likely don't remember how they were as a brand new recruit.but I don't know of many people that I served with who weren't told to lie about something by their recruiter. Hope everything works out for you in the end.