A Survey Of Anticoagulation Therapy For Patients With Nonvalvular Atrial Fibrillation

ObjectiveTo investigate the current status of antithrombotic treatment in patients with nonvalvular atrial fibrillation(NVAF).To compare both the efficacy and safety of wafarin,aspirin(100mg/d) and non- antithrombotic therapy for antithrombotic prevention and identify the optimal intensity of anti-coagulation with warfarin in patients with NVAF.Methods(1)Retrospective analysis of hospital records were taken from patients with primary diagnosis of NVAF(CHADS2≥2),from Jan.2005 to Jan.2008 inpatients in department both cardiology and neurology.(2) Patients enrolled were devided into wafarin group,aspirin group and non-antithrombotic drug groups according to the therapy they received to analyze the clinical evidence.(3)Futhermore,the patients in warfa- rin group were divided into 4 subgroups according to the inter national normalized ratio (INR) range in order to identify the optimal intensity of warfarin.Results(1)There were 203 patients with NVAF who were enrolled ,male and female cases were 122(60.1%)and 81(39.9%)respectively.Mean age was(71.7±8.2)years old.The median follow-up period was 11 months.Of the total patients,74 cases (36.5%)were received warfarin,98 cases (48.2%) were received aspirin and 31 cases(15.3%)were not received any anti- thrombotic drug.(2)The risk of thromboembolism and ischaemic stroke in the warfarin group was significantly lower than that in the non- antithrombotic drug group (12.8%vs46.9%,9.0%vs39.5%,P<0.05),and the relative risk reduced 75.2% and 79.1% respectively.Compared with the aspirin group,the warfarin group reduced markedly the risk of thrombo- embolism event and ischaemic stroke(12.8%vs25.6%,9.0%vs20.3%,P<0.05),and the relative risk reduced 4.4% and 59.3% respectively.The risk of thromboembolism and ischaemic stroke in the aspirin group was lower than that in the non-antithrombotic drug group(25.6%vs46.9%, 20.3%vs9.5%,P<0.05),relative risk reduced 45.6% and 48.6% respect- tively.There was no significant diferences of the all-cause death rate,combined point of any event,bleeding and major bleeding among the three groups.(3)Of the 10 thromboembolic events occured during warfarin therapy,9 occurred with INR<1.50.The incidence of thromboembolism and ischaemic stroke in patients of INR less than 1.50 was significantly higher than those of INR with 1.50～1.99, 2.00～2.49 and≥2.50(P<0.05). There were no differences of thromboembolism and ischaemic stroke among patients of INR 1.50～1.99,2.00～2.49 and≥2.50.The incidence of bleeding in patients of INR≥2.50 was significantly higher than those of INR with 1.50～1.99 and 2.00～2.49 (P<0.05).There was no difference of major bleeding among the four subgroups.By correspondence analysis, non-clinical evidence is close to INR 1.50～1.99 and 2.00～2.49.Conclusions(1)Warfarin is underused in patients with NVAF who had indications of anticoagulation.(2)Patient treated with warfarin can reduce the thromboembolism event of patients with NVAF (CHADS2≥2).Futhermore, patients of INR between 1.50 and 2.49 were associated with the lowest combined rate of thromboembolism and bleeding.(3)Aspirin(100mg/d) can reduce the embolism event in patients with NVAF(CHADS2≥2), however its effect is less than warfarin.(4)For the patients with NVAF(CHADS2≥2), normalization of anticoagulation can decrease the complication of embolism and bleeding with the largest extend.