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Despite the development of new oral agents over the last decade, vitamin K antagonists (VKAs) remain the most widely used anticoagulants for treating and preventing thromboembolism worldwide. In Chile, the Ministry of Health indicates that acenocoumarol should be used in preference to any other coumarin. Complications of inappropriate dosing are among the most frequently reported adverse events associated with this medication. It is well known that polymorphisms in pharmacokinetic and pharmacodynamic proteins related to coumarins (especially warfarin) influence response to these drugs. This work analyzed the impact of CYP2C19*2 ( rs4244285 ), CYP1A2*1F ( rs762551 ), GGCx ( rs11676382 ), CYP2C9*2 ( rs1799853 ), CYP2C9*3 ( rs1057910 ), CYP4F2 ( rs2108622 ), VKORC1 ( rs9923231 ), VKORC1 ( rs7294 ), CYP3A4*1B ( rs2740574 ), and ABCB1 ( rs1045642 ) polymorphisms on time to therapeutic range for oral anticoagulants in 304 Chilean patients. CYP2C9*3 polymorphisms were associated with time to therapeutic range for acenocoumarol in Chilean patients, and the CYP4F2 TT genotype, MDR1 A allele, CYP1A2 A allele, and CYP3A4 T allele are promising variants that merit further analysis. The presence of polymorphisms explained only 4.1% of time to therapeutic range for acenocoumarol in a multivariate linear model. These results improve our understanding of the basis of ethnic variations in drug metabolism and response to oral anticoagulant therapy. We hope that these findings will contribute to developing an algorithm for VKA dose adjustment in the Chilean population in the near future, decreasing the frequency of stroke, systemic embolism, and bleeding-related adverse events.

Warfarin and acenocoumarol are used in various cardiovascular disorders to improve the prognosis of patients with thromboembolic disease. However, there is a lack of substantial efficacy and safety data on antithrombotic prophylaxis in several countries, particularly in Latin America. The aim of this study was to provide information about the efficacy of anticoagulants in Chilean patients. Data were collected from databases of the Western Metropolitan Health Service, Santiago, Chile. We identified 6280 records of patients receiving anticoagulant treatment. The three most common diagnoses were rhythm disorder (43.7%), venous thrombosis (22%), and valvular prosthesis (10.7%). The majority of patients (98.5%) received acenocoumarol while 1.5% of patients received warfarin, at weekly therapeutic doses of 13.6 mg and 30.4 mg, respectively. For total diagnoses, the median time in the therapeutic range was 50%. However, better results, 66.7%, were observed when a telemedicine strategy was used only in Santiago Province. Our findings emphasize that in Chile, where the number of patients receiving anticoagulant treatment increases every year, telemedicine, by committed teams, improves the use of oral anticoagulants and is able to increase quality indicators of anticoagulant treatment care.