A lower daily dose of aspirin ( < 100 mg ) may be associated with a lower major bleeding risk than higher doses .
Adding antiplatelet therapy , either dipyridamole or low-dose aspirin , to oral anticoagulation decreases the risk of systemic embolism or death among patients with prosthetic heart valves .
The risk of major bleeding is increased with antiplatelet therapy .
These results apply to patients with mechanical prosthetic valves or those with biological valves and indicators of high risk such as atrial fibrillation or prior thromboembolic events .
The effectiveness and safety of low-dose aspirin ( 100 mg daily ) appears to be similar to higher-dose aspirin and dipyridamole .
BACKGROUND Patients with prosthetic heart valves are at increased risk for valve thrombosis and arterial thromboembolism .
Oral anticoagulation alone , or the addition of antiplatelet drugs , has been used to minimise this risk .
An important issue is the effectiveness and safety of the latter strategy .
OBJECTIVES This is an up date of our previous review ; the goal was to create a valid synthesis of all available , method ologically sound data to further assess the safety and efficacy of combined oral anticoagulant and antiplatelet therapy versus oral anticoagulant monotherapy in patients with prosthetic heart valves .
[Significance of combined use of anticoagulants and antiplatelet agents in the early stage after prosthetic valve replacement].
Patients who had undergone prosthetic valve replacement were treated with warfarin ( anticoagulant ) alone or in combination of ticlopidine ( 200 mg/day ) or aspirin ( 81 mg/day ) ( anti-platelet agents ) . The study of blood coagulation factors and platelet aggregation were carried out with these cases . 1 ) The patients ( n = 24 ) receiving  warfarin for 21 days after prosthetic valve replacement revealed marked increases in PIVKA-II and vitamin K1-epoxide . The protein C activity was significantly lower than that before the operation . High levels of more than 5 ng/ml of TAT were found before operation and after warfarin administration for 21 days . 2 ) Warfarin did not affect platelet aggregation , whereas ticlopidine inhibited ADP-induced platelet aggregation and aspirin inhibited both collagen-induced and arachidonic acid-induced aggregation . In conclusion , combined use of anticoagulants and antiplatelet agents after prosthetic valve replacement will suppress not only the blood coagulation but also the platelet aggregation systems
A lower daily dose of aspirin ( < 100 mg ) may be associated with a lower major bleeding risk than higher doses .
Adding antiplatelet therapy , either dipyridamole or low-dose aspirin , to oral anticoagulation decreases the risk of systemic embolism or death among patients with prosthetic heart valves .
The risk of major bleeding is increased with antiplatelet therapy .
These results apply to patients with mechanical prosthetic valves or those with biological valves and indicators of high risk such as atrial fibrillation or prior thromboembolic events .
The effectiveness and safety of low-dose aspirin ( 100 mg daily ) appears to be similar to higher-dose aspirin and dipyridamole .
BACKGROUND Patients with prosthetic heart valves are at increased risk for valve thrombosis and arterial thromboembolism .
Oral anticoagulation alone , or the addition of antiplatelet drugs , has been used to minimise this risk .
An important issue is the effectiveness and safety of the latter strategy .
OBJECTIVES This is an up date of our previous review ; the goal was to create a valid synthesis of all available , method ologically sound data to further assess the safety and efficacy of combined oral anticoagulant and antiplatelet therapy versus oral anticoagulant monotherapy in patients with prosthetic heart valves .