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

I would try good ole prayer, ask for the creator to help you with your decision making in the future and to stop lying to get what you want. King David was a warrior, but often talked to God, he’s a good example for any warrior. He also tells you how he got “a head”.

Ok yeah you should have mentioned this beforehand. Now they know. The best thing is to be honest from this point forward. It will be better for you in the long run. There are medical waivers, you just need to be diligent in serving your country and keeping that at the forefront. It is not lieing if you failed to mention it is just that you didn't mention it. If you are honest to begin with then you will be on a straight path. Good luck with your enlistment. I wish you the best either way and pray that you get the waiver. Just don't waste the chance to do what's right. We all need second chances. So take this as your second chance and make good on it.

If you otherwise meet the physical requirements to get into the branch of service you're planning on serving in, I wouldn't be overly concerned from that perspective. If your targeted job requires a security clearance, well, you just better be sure that every time your clearance is up for review that you honestly disclose everything on every question. Especially since you just outted yourself on a public social media platform, but of course, you should anyway. Best wishes and hoping you have a long and successful career in front of you.

Now that the cat is out of the bag so to speak, I would not concern yourself about omitting the fact that you have a heart murmur. It is true in cases that youth do grow out of the murmur.
Now let's reel this back a bit. Did you discuss this heart murmur with your recruiter? A recruiter and Station Commander need to uncover any and all issues. APPLESMDT was, maybe still used to pre qualify applicants. This acronym uncovers everything. It is of my opinion your recruiter (more than likely) was aware of this. If the Recruiter and Station Commander did not know, then both failed to uncover issues before you went to MEPS. Again that is my opinion.
Having said all that, I would not worry about NOT listing this on your DD FM 2807-2. About 75 % of the time, the heart murmur will be approved. After your consult, your recruiter will submit a med waiver and that may take another week to get approved. Keep in mind, a heart murmur may prevent you from certain MOSs. Be advised and medical waiver can be disapproved. But my experience in the past has indicated a good approval rating for the heart murmur... good luck...Hoooah!

I'm a veteran now so hopefully I can say this without the feds knocking on my door.
I had medical issues as well but at the time I was in shape doing special work out programs and I went through a lot to even get to MEPS. My recruiter said the word of the day was no. No, no, no, no, no, no. Sounds like an integrity violation right? Who gives a shit. You're trying to get somewhere in your life and you should be willing to do whatever it takes and not quit. Later on down the road you can look back and laugh.

I understand that you want to serve your country! But the gentleman within this post have stated core values that one should display in every day life situations. In this case, please utilize integrity and tell your recruiter the truth. Please do not waste your time and many others who are Valiantly trying to help you accomplish your goal in serving our great nation. On a side note, in training you will be pushed well above your limits and to place yourself in a situation where you could possibly put your life at risk is totally uncalled for! Please “Do the right thing”!

I wouldn't worry about it. I also had a heart murmur which I did not lie about, and the only thing they did differently for me as compared to other recruits was to emblazoned two horizontal red bars on my yellow PT shirt (USMC Parris Island in 1988). Apart from that I had a great enlistment, and it turned out to be a minor issue at most.

Some folks here are more interested in trying to shame you for you volunteering to serve your country. Put their opinions where they belong - in the circular file of unnecessary bullsh*t that you forgot about.

Actually I did the same, but it was flat feet. I confessed while at medical in boot and the doctor told me that it wasn't something that would have excluded me from service, so it wasn't an issue. I would think that your situation is the same since your doctor said it wasn't a big deal and you could get in with it if it's not too bad or you did mostly grow our of it. The worst that could happen is they let you stay in and you have a life ending cardiac event, but I'm sure if they tell you it's ok then no one will care that you lied. Other than death the worst that will happen is an immediate discharge and your record will reflect that you were medically discharged and unable to retry.
No more lying. and as far as that goes, I don't think they can look at your medical records not generated by the military without getting you to sign a permission document. You can refuse, but it will seal your fate to be discharged.

If they weren't going to, you just made sure that they will. Why in the world would you post the fact that you committed perjury on a public site?

I'm with CSM Sagara, man up!