A COMPARISON OF A MODERATE WITH MODERATE-HIGH INTENSITY ORAL ANTICOAGULANT TREATMENT IN PATIENTS WITH MECHANICAL HEART-VALVE PROSTHESES

Background. The long-term administration of oral anticoagulants to pat ients with mechanical heart valve prostheses is generally accepted. Ho wever, the appropriate intensity of oral anticoagulant treatment in th ese patients is still controversial. Methods and Results. From March 1 991 to March 1994, patients referred to the Padova Thrombosis Center w ho had undergone mechanical heart valve substitution at least 6 months earlier were randomly assigned to receive oral anticoagulants at mode rate intensity (target INR = 3) or moderate-high intensity (target INR = 4). Principal end points were major bleeding, thromboembolism and v ascular death. Minor bleeding was a secondary end-point. A total of 10 4 patients were assigned to the target 3 group and 101 to the target 4 group; they were followed for from 1.5 years to up 4.5 years (mean, 3 years). Principal end-points occurred in 13 patients in the target 3 group (4 per 100 patient-years) and in 20 patients in the target 4 gro up (6.9 per 100 patient-years). Major hemorrhagic events occurred in 1 5 patients, 4 in the target 3 group (1.2 per 100 patient-years) and 11 in the target 4 group (3.8 per 100 patient-years) (p = 0.019). The 12 recorded episodes of thromboembolism, 4 of which consisted of a visua l deficit, were all transient ischemic attacks, 6 in the target 3 grou p (1.8 per 100 patient-years) and 6 in the target 4 group (2.1 per 100 patient years). There were 3 vascular deaths in each group (0.9 and 1 per 100 patient-years for target 3 and target 4 groups, respectively) . Minor bleeding episodes occurred 85 times (26 per 100 patient-years) in the target 3 group and 123 times (43 per 100 patient-years) in the target 4 group (p = 0.001). Conclusions. Mechanical heart valve patie nts on anticoagulant treatment who had been operated on at least 6 mon ths earlier experienced fewer bleeding complications when maintained o n a moderate intensity regimen (target INR = 3) than those on a modera te-high intensity regimen (target INR = 4). The number of thromboembol ic events and vascular deaths did not differ between the two groups.