DVT Prophylaxis in Patients Taking Aspirin

Primary Recommendation

For patients taking aspirin for primary prevention of cardiovascular disease or stable coronary artery disease, aspirin should be suspended while receiving anticoagulant therapy for VTE prophylaxis, as the combination of anticoagulation plus aspirin increases major bleeding risk by approximately 26% (RR 1.26, 95% CI 0.92-1.72) compared to anticoagulation alone, based on very low certainty evidence 1
The American Society of Hematology recommends suspending aspirin in patients taking anticoagulant therapy for VTE prophylaxis, unless there is a compelling cardiovascular indication requiring dual therapy, due to the increased bleeding risk without clear additional benefit 1

Aspirin should be continued only if the patient has had a recent acute coronary event or recent coronary intervention, as the cardiovascular benefit may outweigh bleeding risk in these high-risk cardiac patients 1
The American College of Cardiology suggests that patients with unstable coronary syndromes requiring dual antiplatelet therapy represent an exception where the cardiovascular benefit may outweigh bleeding risk 1

Standard prophylactic dosing is enoxaparin 40mg subcutaneously once daily, which should be continued for the duration of hospitalization or until the patient is fully ambulatory 3
The National Comprehensive Cancer Network recommends enoxaparin 40mg daily for at least 7-10 days postoperatively in surgical patients with cancer, with consideration for extended prophylaxis up to 4 weeks in high-risk cases 3

The combination of prophylactic-dose LMWH plus aspirin increases bleeding risk without proven additional VTE prevention benefit, with major bleeding events increasing by approximately 5 more per 1000 patients 1
The European Society of Cardiology notes that enoxaparin 40mg once or twice daily showed similar safety profiles when used alone in bariatric surgery patients 4

Cancer patients undergoing major surgery should receive enoxaparin 40mg daily, as it is preferred over aspirin for thromboprophylaxis 3
Obese patients (BMI >40) can receive enoxaparin 40mg daily, although some protocols use twice-daily dosing 4
Multiple myeloma patients on lenalidomide should receive LMWH, as it is preferred over aspirin in high-risk patients, while aspirin may be considered only in low-risk patients 6