Optimal maintenance dose of warfarin in patients with prosthetic heart valves in Kermanshah, West of Iran

Warfarin is a widely-used anticoagulant drug in clinical practice. However, its use is with caution due to serious side effects including gastrointestinal bleeding (up to 5%) and mortality (0.5% – 2.0%). Therefore, the correct dosing of warfarin is of paramount importance. We examined warfarin maintenance dose requirements in 115 outpatients in Kermanshah, North-West of Iran, who had a history of isolated aortic or mitral valve replacement and were on stable maintenance doses of warfarin with international normalized ratios (INR) of 2.0 – 2.5. The mean daily warfarin requirement was 4.6 ± 1.8 mg, with 75% of patients requiring < 5 mg/day. No significant difference was noted between the two sex groups; however, there was a noticeable decline in dose requirement by increasing age. This study suggests that a relatively small dose (as low as 5 mg) of warfarin is required for maintaining anticoagulation in our patients.