Özet:

Objectives:  To evaluate the treatment choices applied to patients with mechanical heart valves who were determined as resistant to warfarin. Materials and Method: The study comprised 40 patients (22 male, 18 female; mean age 58.15 years) who had been fitted with mechanical heart valves and were under International Normalised Ratio (INR) monitoring between 2006 and 2014. Until the target level was achieved, INR monitoring was applied once a week and thereafter once a month. The INR target values were applied as 2-3 for mechanical valves in the aorta position and as 2.5-3.5 for mechanical valves in other positions and for high-risk patients. Patients using a weekly dose of <75mg warfarin were evaluated as the normal dose group and those using ≥ 75mg warfarin were evaluated as the high dose group.  Results: The INR monitoring period of the patients ranged from 1 month to 28 years (mean 10.22 years). The normal dose group comprised 36 patients (90%) and the high dose group 4 (10%). In 3 of the high dose group, the target INR values were obtained with an increased dose of Coumadin and in 1 patient, the target INR level was reached with 300mg/day acetyl salicylic acid together with warfarin.  Conclusion: Warfarin resistance in individuals using anti-coagulant medications has been reported at approximately 5%. There are acquired and genetic factors which affect the warfarin dose. When warfarin resistance is encountered, firstly the patient must be questioned in detail as to medication compatibility for concomitant diseases and interaction of diet or medications with warfarin. When it has been determined that these factors are not present, then genetic factors should be considered. Increased treatment dose for patients determined as warfarin-resistant should be a combination of warfarin with low molecular weight heparin or combined clopidogrel and acetyl salicyclic acid.   

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