NDW.
If everything is found to be normal then all is well. If you do indeed have a heart murmur then, based on the rules from when I went through OASC in 1999, I'm afraid the news is not good.
Bear in mind I'm not a doctor and I can't swear that my information is bang up to date but you should be prepared for either eventuality.
Sorry to be the bearer of bad tidings and I hope that everything turns out fine. If you are suitable in all other areas and then miss out because of a hitherto unknown medical complaint it is a bitter pill to swallow.
All the best and others may be able to amplify my points further.
BV