I Have Polycythemia Not Vera For Almost 45 Years Discovered

I have polycythemia not vera for almost 45 years discovered at age 19 which I have managed through blood draws every 60-90 days. My hemocritic 55-59 and hemoglobin 18.5 I am 69 years old and recently had a mild stroke. Due to this recent event, I am looking for options to help prevent future strokes. One idea is to increase blood draws to monthly. If this is unsuccessful in getting me down to 45 percent, I am not sure of my options. Any suggestions outside chemo treatments?