I have an Alive Cor that I have been using to track my heart rhythm. Last two days I have had a skip and then my heart takes off. It takes off but gradually comes down. I sent in the EKG for a clinic review by a cardiologist and one said serious need to follow up immediately with a doc (diagnosis was sinus tachycardia but cant rule out an atrial tachyardia rhythm) or PAT they called it, the other doctor just said it needed review by a doctor and said the same thing Sinus Tachycardia or possible Atrial Tachycardia. What is atrial tachyardia and how can they not tell which one it is? My rate was 154. The heart rate started suddenly but gradually went down. I am not nervous and dont know what to do.