Is There An Effective Herbal Substitute For Isosorbide Mononitrate That Won’t Interfere With My Pilot Training?

I want to know of a substitute such as Herbal for Isosorbide Mononitrate, take once a day 1/2 of 60MG had a blood clot in my lungs 5 years ago then had two Stents; 1 on Right & 1 on Left w/a lead to help left side to pump better last nuclear test it working at 42%. Never had a Heart Attack or Chest Pains-but it is interfering with my Pilot Training because its call a nitrate.