An EKG is only a snapshot in time. Stress tests and Echocardiograms also show just a brief period. Ask for a "21-day Event/Holter Monitor" from your cardiologist. This will document you heart rhythm day and night for 3 weeks. They can see what changes happen with activity. It took 4 different doctors, 10 appointments and 1 1/2 years to finally have 'proof' of what I have been describing-a racing heart rate that is disproportionate to my activity. From this, I got on Metoprolol and have had better rate control. A cardiac MRI may be indicated depending on the event monitor results.
PVC's, in and of themself, are quite common. The problem comes when they come together (couplets), three together (triplets), runs of four or more together (salvos), come every other or every third beat (bigeminy/trigeminy) or the stimulus comes from different spots in the ventricle (multi-focal). Also at issue is when you become symptomatic with them-short of breath, light headed, have chest pain/pressure, blood pressure drops, pass out. In general, being well hydrated & limiting caffeine helps the frequency of episodes.
RMS, ER RN