I had same Hx, but my SVT started ant ange 19 and at 57 I had it for 4 hours before went to ER. Before that it usually lasted seconds to a minute or two. I do have a few really fast flutters that even made me dizzy; that wasn’t a good sign, They gave me IV Adenosine in the ER which was scary. Stopped my heart beat literally! I saw my heart flatline for a couple seconds and felt the feeling of “ Impending Doom” as they say! Thank God it came back to Normal Sinus rhythm within seconds. I tried metoprolol after that and had all the Cardiac test possible and all checked out. On the Metoprolol it dropped my BP very low. I already have low BP. So since I couldn’t tolerate the Beta Blocker I had to have a Cardiac Ablation and they burned the spot in my right atrium that was causing the PSVT. It’s like a Cardiac Cath under anesthesia of course. I’ve been fine ever since. I enjoy my cofffee every morning and my Diet Coke when I eat out. Only suggestion regarding meds is maybe taking a magnesium supplement. Talk to your Dr about that. There are different forms of it.