I have MVP, and occasionally my heart will be beating normally, then I have a half-heartbeat followed by a very strong heartbeat, like bah-BOOM. It's what is know as PVC's (I forget exactly what the acronym stands for). PVC's are when you have an extra half-beat before each beat. I usually only get them if I've had caffeine, then gone into class or church. I have no idea why it happens in these buildings only, but the PVC's go away after one or two episodes. It is a little scary, but the way I understand it, it's common in people with MVP.