My recent struggle with tachycardia was blamed on stress, anxiety, depression, and my weight. So YES obviously there can be a connection.
BUT...... if you feel that the tachycardia is not related if you really dont feel stressed out before it happens then I would not hessitate to ask the Dr why and keep asking untill you get an answer. I was in hospital on the weekend and the Dr's finally admitted there might be another reason for my tachycardia they diagnoised me with inappropriate sinus tachycardia(IST), and put me on some meds which have had an amazing result for me.
IST is not dangerous but it was seriously impacting my life and abilty to walk and exercise. If at any stage you feel the tachycardia is inpacking your life too much with too many symptoms eg sweating, fatigue, after minimal exertion I really would not hesiatate to talk to you Dr about why.
Oh yeah without a doubt it can along with alot of other no so good for us things.....if you are sure you are tach'ing you need to get it checked out by a doc...when we tach it is just like when our car tach's into the red and then look what happens to the engine...
Stress can do a ton of bad stuff. You can have heart symptoms ,shortness of breath,weakness,you name it. I have irregular heart beats. They get much worse when I stress out. If your heart checks out, you can bet it is stress. Good luck and God bless.