For some reason me thinks 'Guest might have asked it seriously.. but then maybe not? I suspect many people today are trying good'ol homegrown today to relieve stress and maybe even physiological pain relief to a degree. I mean if it works...
I can only give you my personal opinion and experience.
I have been using marijuana medically for the past 8 years. Smoking it. I don't plan on stopping as it really helps out with a lot of my issues, and prevents me from having to take certain pharmaceuticals.
After surgery (a little over a month ago) i didn't use any marijuana until I got out of the hospital. My doctor said I could vape modestly. Notice I say to vape and not smoke as any kind of smoke can cause plaque build up. Especially if you plan on using marijuana regularly. I recommend you buy A good dry herb vaporizer, which will run you 150-300 dollars. Well worth it. Much healthier form of consuming marijuana.
To answer your question more directly. Smoking marijuana shouldn't affect your inr levels.
Not only can it cause plaque build up, but pot also raises your blood pressure.
So if your condition has some high blood pressure issues, then although you may feel relaxed while smoking, it can actually cause you more harm.