Biomedical subjects

A Zasso

Publications and source records attributed to A Zasso.

4 recordsLinked to original sources

PubMed1998

Effectiveness of fixed minidose warfarin in the prevention of thromboembolism and vascular death in nonrheumatic atrial fibrillation.

Adjusted-dose warfarin is effective for stroke prevention in patients with nonrheumatic atrial fibrillation (AF), but the risk of bleeding is high, especially among the elderly. Fixed minidose warfarin is effective in preventing venous thromboembolism with low risk of bleeding and no need for frequent clinical monitoring. Patients > 60 years with nonrheumatic AF were randomized in an open-labeled trial to receive fixed minidose warfarin (1.25 mg/day) or standard adjusted-dose warfarin (International Normalized Ratio [INR] between 2.0 and 3.0). Primary outcome events were ischemic stroke, peripheral or visceral embolism, cerebral or fatal bleeding, and vascular death. Secondary end points were major bleeding, myocardial infarction, and death. This study was discontinued before completion in light of publication of the Stroke Prevention in Atrial Fibrillation III trial, which indicated that low-intensity fixed-dose warfarin treatment (i.e., INR < 1.5) was insufficient for stroke prevention in high-risk patients with nonrheumatic AF. From a total of 1,209 considered patients, 303 were randomized to be studied (150 in the minidose group and 153 in the adjusted-dose group). Mean follow-up was 14.5 months. The rate of cumulative primary events was 11.1% (95% confidence intervals [CI] 4.0 to 18.2) in the fixed minidose group and 6.1% (95% CI 1.1 to 11.1) in the adjusted-dose group (p = 0.29). The rate of ischemic stroke was significantly higher in the minidose group (3.7% vs 0% per year, p = 0.025). Major bleedings were more frequent in standard treatment group (2.6% vs 1% per year, p = 0.19). Most thromboembolic complications occurred at INRs < 1.2, whereas the majority of hemorrhages occurred at INRs > 3.0. No significant difference in primary outcome events was observed in the abbreviated study. However, the significantly increased occurrence of ischemic stroke in the fixed minidose warfarin group suggests that this regimen does not protect patients with nonrheumatic AF.

Aged↗

PubMed1997

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 patients with mechanical heart valve prostheses is generally accepted. However, the appropriate intensity of oral anticoagulant treatment in these patients is still controversial. METHODS AND RESULTS: From March 1991 to March 1994, patients referred to the Padova Thrombosis Center who had undergone mechanical heart valve substitution at least 6 months earlier were randomly assigned to receive oral anticoagulants at moderate intensity (target INR = 3) or moderate-high intensity (target INR = 4). Principal end points were major bleeding, thromboembolism and vascular death. Minor bleeding was a secondary end-point. A total of 104 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 group (6.9 per 100 patient-years). Major hemorrhagic events occurred in 15 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 visual deficit, were all transient ischemic attacks, 6 in the target 3 group (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 patients on anticoagulant treatment who had been operated on at least 6 months earlier experienced fewer bleeding complications when maintained on a moderate intensity regimen (target INR = 3) than those on a moderate-high intensity regimen (target INR = 4). The number of thromboembolic events and vascular deaths did not differ between the two groups.

Administration, Oral↗

PubMed1993

Reversal of excessive effect of regular anticoagulation: low oral dose of phytonadione (vitamin K1) compared with warfarin discontinuation.

To determine the best way to reverse the excessive effect of regular anticoagulation in patients with INR > 5 and no bleeding complications, 23 patients with INR > 5 were randomly subdivided into two groups: group A (n = 12) discontinued warfarin for one day and group B (n = 11) received 2 mg of vitamin K1 orally in addition to the usual warfarin dose. INR was determined after 24 h (day 1), after which both groups continued with their usual dose of warfarin. After 48 h (day 2), warfarin dosage was changed according to the INR value. On day 9, INR values were determined again. Five out of twelve patients in group A had INR values > 5 on day 1. One patient in group A had an INR value < 5 both on days 1 and 2. All eleven patients in group B had INR values < 5 on day 1, and all but one on day 2. On day 9, INR values were acceptable (INR 2.0-4.5) in ten group A patients and eight group B patients. These findings suggest that a low oral dose of vitamin K1 is a convenient treatment for excessive anticoagulation in patients with no bleeding complications.

Adult↗

PubMedDate not supplied

Low intensity warfarin therapy.

BACKGROUND AND OBJECTIVE: Several studies comparing different intensities of oral anticoagulant treatment have clearly shown a relationship between bleeding complications and prolongation of prothrombin time. In the early '50s, de Takats suggested that low-dose oral anticoagulants might be as effective as higher doses in preventing thrombosis, at a lower risk of bleeding. This review article examines the potential of low dose warfarin therapy. INFORMATION SOURCES: The authors have been working in this field, contributing original papers. In addition, the material examined in this article includes articles published in the journals covered by the Science Citation Index and MedLine. STATE OF ART AND PERSPECTIVES: The hypothesis that low-dose oral anticoagulants can be effective in preventing thrombosis was first proven by experiments in animal models, and showed that a prothrombin time ratio as low as 1.14 using rabbit brain thromboplastin was still able to confer some inhibition of experimental thrombosis. Low-dose or very low-dose warfarin were subsequently demonstrated to be effective in patients with morbid obesity and decreased antithrombin III functional and antigenic levels, in patients with indwelling catheters, in patients undergoing gynecological surgery, as well as in patients with stage IV breast cancer. Low-dose warfarin is also effective in the prevention of embolic strokes in patients with non-rheumatic atrial fibrillation. However, older patients (> 75 years), who have a very high risk of bleeding, might be safer taking a very low dose of warfarin (i.e., a daily dose of 1-1.25 mg). Moreover, after a period of run-in, a fixed, very low-dose warfarin schedule does not need further laboratory control, which is a factor that could contribute to the full acceptance of treatment by patients and could stimulate a broader prescription of warfarin for the primary prevention of stroke in older patients with nonrheumatic atrial fibrillation. Therefore, we have organized a multicenter clinical trial in which 1000 patients with non-rheumatic atrial fibrillation will be randomized to receive either a fixed mini-dose of warfarin or a standard dose. Positive results might permit the treatment of most older patients with non-rheumatic atrial fibrillation, creating a benefit for the community as a consequence of its effective prevention of disabling strokes.

Animals↗