When i was in the hospital i had an Echocardiograph and it showed the slightly enlarged valve and murmur. In my case i think my back is arched funny and i may have lordosis which i think may put pressure on my lungs or heart when i lay down causing the apnea.
A friend of mine a few years later was hooked on ephedrine and over a period of months it began to take its toll. One day he took his usual ammount and he had bad chest pain and had to go to the hospital. His tests said he had a heart attack but since he was so young the doctors werent convinced, they figured he was just on drugs, which technically he was i guess. But he was released a few days later and recovered fully a month or two afterwords. So im thinking in my case the underlying mvp caused me to have more damage than other people would. But i had mvp all my life with no pain or symptoms until i took the pill.
They also made me wear a halter monitor a few times to record my heart rate during my day to day activities. Maybe that could prove it for you? This all, of course, was when i was young and covered under insurance. Now that im over 18 and making too much for medicaid i imagine such tests would be very expensive.