Is it possible your slower heart rate is unrelated to med you haven taken for years? Sometimes meds will uncover changing conditions with our hearts. My case....taking an anti arrhythmia drug uncovered sinus node dysfunction. It causes brachycardia. Verdict is out still w cardiologists whether it causes aFib or aFib causes sinus node dysfunction. Finally, after experiencing rates in the 40’s and 50’s, I agreed to a pacemaker recommended by my Mayo Clinic EP cardiologist.( he had been telling me for 4 yrs I needed PM). Boy, do I feel better. No pauses or slow rates. I take Sotalol to minimize aFib which causes very slow bpm). My PM is set at 60 bmp on low end - 130 bmp high end to allow for exercise. Hope this helps. A 14 day event monitor will give your Dr info he needs.