yes I'm on warfarin for an On-X aorta valve. I only keep a chart when I have them to inform the doctor then next time I see him. You should have him call his doctor if you're still concerned.Are you on anti-coagulants for your afib? My hubby can't really go to the hospital every time he has been in afib if it is constant. He is on Warfarin, so doesn't that mitigate the stroke risk?