They can tell from the wave pattern on the ECG. If they say they are just psvt's (like mine)
then that's what they are. I also have anxiety and panic attacks and when I have an episode of SVT I keep 'talking to myself' that its OK, the worse I panic the worse it gets. You have to try really hard to tell yourself that you will be Ok and that it will stop soon. Easier said than done, but you have to try. I have been having these for years and take beta blockers atenelol in small doses every morning and it works if you persist with it. Takes a couple ofweeks to get used to it. I also take a valium if I get an attack, and gulp down gassy drink like coke and really burp, which often reverts it. You'll be Ok.
They can see how the heart is acting overall from the monitor. An occasional PAC or PVC that doesn't lead to another arrhythmia is probably just an electrical hiccup in the heart. I average about 1-5 per minute every day. Some days I have more.
Have you had an echo done of the heart yet? That way they can get a clear picture of the heart itself and the valves. If those all look normal, then the ectopics you're having are of no concern. Did he tell you how many you have a day? Some people have tens of thousands. That would get annoying and tiring.