I've mild mvp n hyperthyroid. My at rest heartbeat can go up to 98 at times n I feel short of breath. My thyroid is under ctrl. Shd I b concerned?

Rapid heart rate. Mild mitral valve prolapse is well known to cause palpitations, but this is not serious, and usually goes away with exercise. Assuming your middle-aged or younger, i suspect the mild shortness of breath you feel is due to deconditioning, or not being used to getting your heart rate up with regular exercise. Best approach to this is to start a walking program at 5-10 minutes and gradually increase.