If someone gets svt every 3-6 weeks that lasts less than 5-10 seconds is there any reason it would stop self-terminating or get worse in future?

Prediction impossibl: Many things can happen in the future, including further heart problems (heart attack, as an example), electrolyte abnormalities (from kidney disease), &c so it is impossible to predict what the future holds. Many people with SVT have a stable pattern for the rest of their lives; others get arrhythmias (& symptoms) more frequently. Talk to your Cardiologist regarding your concerns or use HT Prime.