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 .
A comparison of aspirin with placebo in patients treated with warfarin after heart-valve replacement.
BACKGROUND Despite the use of warfarin , major systemic embolism remains an important complication in patients with heart-valve replacement . Although the addition of antiplatelet agents has the potential to reduce this complication , their efficacy and safety when given in combination with warfarin are uncertain . METHODS In a r and omized , double-blind , placebo-controlled trial , we assessed the efficacy and safety of adding aspirin ( 100 mg per day ) to warfarin treatment ( target international normalized ratio , 3.0 to 4.5 ) in 370 patients with mechanical heart valves or with tissue valves plus atrial fibrillation or a history of thromboembolism . RESULTS A total of 186 patients were r and omly assigned to aspirin  and 184 to placebo  , and they were followed for up to 4 years ( average , 2.5 ) . Major systemic embolism or death from vascular causes occurred in 6 aspirin-treated patients ( 1.9 percent per year ) and 24 placebo-treated patients ( 8.5 percent per year ) ( risk reduction with aspirin , 77 percent ; 95 percent confidence interval , 44 to 91 percent ; P < 0.001 ) . Major systemic embolism , nonfatal intracranial hemorrhage , or death from hemorrhage or vascular causes occurred in 12 patients assigned to aspirin ( 3.9 percent per year ) and 28 patients assigned to placebo ( 9.9 percent per year ) ( risk reduction , 61 per cent ; 95 percent confidence interval , 24 to 80 percent ; P = 0.005 ) ; major systemic embolism or death from any cause occurred in 13 patients ( 4.2 percent ) and 33 patients ( 11.7 percent ) , respectively ( risk reduction , 65 percent ; 95 percent confidence interval , 33 to 82 percent ; P < 0.001 ) ; and death from all causes occurred in 9 patients ( 2.8 percent ) and 22 patients ( 7.4 percent ) , respectively ( risk reduction , 63 percent ; 95 percent confidence interval , 19 to 83 percent ; P = 0.01 ) . Bleeding occurred in 71 patients in the aspirin group ( 35.0 percent ) , as compared with 49 patients in the placebo group ( 22.0 percent ) ( increase in risk , 55 percent ; 95 percent confidence interval , 8 to 124 percent ; P = 0.02 ) ; major bleeding occurred in 24 and 19 patients , respectively ( increase in risk , 27 percent ; 95 percent confidence interval , -30 to 132 percent ; P = 0.43 ) . CONCLUSIONS In patients with mechanical heart valves and high-risk patients with prosthetic tissue valves , the addition of aspirin to warfarin therapy reduced mortality , particularly mortality from vascular causes , together with major systemic embolism . Although there was some increase in bleeding , the risk of the combined treatment was more than offset by the considerable benefit
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 .