I Have Been Experiencing My Heart Skipping A Beat. Its

I have been experiencing my heart skipping a beat. Its mostly noticeable when I am relaxing or laying down. I work at a vocational school and had my instructor hook me up to an EKG machine. The dr at our school thinks it can be left atrial enlargement and PVC. Is this something that can be fatal?? I do plan on seeing a doctor to confirm, but I was concerned that it may be more serious and if I should go to the ER.