I have a artificial heart valve. I have had it for 23 years. bjork shiley. I started having afib back in Oct. of last year. I have been cardio verted two times. I have converted on my own several times. My question is I went and had my INR checked to day and it was 1.7 to low. It is suppose to be between 2.5 to 3.5. I was wondering if there was anyone out there that might be able to tell me how big of risk am I of having a stroke if I go into afib while my blood is this thick and having a artificial valve. I read on the computer that people with artificial valves have a higher risk of stroke than a person that doen't even if they are on a anticoagulant. Sometimes I think I have a worry problem but I am not ready to go yet and I sure don't want to have a stroke. I do know that know matter how hard you try to prevent a stroke it can still happen. Just thought some one out there would have an answer.