RESUMO
BACKGROUND AND OBJECTIVE: Khat is a plant that contains the alkaloids cathine and cathinone which have some amphetamine-like properties. It is cultivated and it's leaves chewed for their euphoric effect. This study intended to elucidate the effect of khat chewing on blood coagulation by using the International Normalized Ratio (INR) value as a calculable benchmark. MATERIALS AND METHODS: In this cohort study, 146 patients with Mechanical Heart Valves (MHV) were assessed for two consecutive visits at one-month intervals. For each visit, the date of surgery, the patient's compliance, the dose of warfarin and the INR reading were assessed by the researcher. RESULTS: Out of 146 patients with MHV, the mean age was 33.72±12.43 years (range, 14-65 years); 82 (56.2%) were female and 64 (43.8%) were male. The results revealed that the mean of absolute INR readings was lower in khat-chewers than non-chewers by average 0.2 on the first and second visits (p = 0.038 and 0.002, respectively). CONCLUSION: Khat chewing has a significant coagulant effect. There was a significant decrease in the value of INR for khat chewers patients with MHV when compared to non-khat chewers.