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Prevention of thromboembolism using aspirin after mitral valve replacement with porcine bioprosthesis
Insights
Aspirin effectively prevents thromboembolism after heart valve replacement surgery. Lower aspirin doses (0.5 gm every 48 hours) were significantly more effective than higher doses (1 gm daily) in preventing embolic events.
Area of Science:
- Cardiology
- Cardiovascular Surgery
- Pharmacology
Background:
- Thromboembolism is a significant risk following prosthetic heart valve replacement.
- Optimal antithrombotic therapy after mitral valve replacement with bioprostheses remains a subject of investigation.
- Current guidelines often recommend oral anticoagulation, but concerns exist regarding bleeding complications and efficacy.
Purpose of the Study:
- To evaluate the thromboembolic rate in patients treated with aspirin monotherapy after mitral valve replacement (MVR) or mitral-aortic valve replacement (MAVR) with porcine bioprostheses.
- To assess the impact of aspirin dosage and specific patient subgroups (atrial fibrillation, giant left atrium, left atrial thrombosis) on thromboembolic events.
- To compare the efficacy of aspirin therapy with traditional oral anticoagulation in this patient population.
Main Methods:
- Retrospective analysis of 768 patients undergoing MVR or MAVR with porcine bioprostheses, treated exclusively with aspirin.
- Subgroup analysis based on presence of atrial fibrillation, giant left atrium, left atrial thrombosis, and aspirin dosage (1 gm daily vs. 0.5 gm every 48 hours).
- Calculation and comparison of thromboembolic rates across different patient categories and treatment regimens.
Main Results:
- The overall thromboembolic rate was low at 1.4% (11/768).
- No embolic events occurred in patients in sinus rhythm.
- Patients receiving 0.5 gm of aspirin every 48 hours had a significantly lower embolic rate (0.4%) compared to those receiving 1 gm daily (3%) (p < 0.01).
- Embolic rates were 1.9% in atrial fibrillation, 0% in giant left atrium, and 2.4% in left atrial thrombosis subgroups.
Conclusions:
- Aspirin monotherapy is highly effective in preventing thromboembolism after porcine bioprosthetic mitral valve replacement.
- A lower, less frequent aspirin dosage (0.5 gm every 48 hours) demonstrates superior efficacy and reduced thromboembolic events compared to a higher daily dose.
- Aspirin therapy may offer protection comparable or superior to oral anticoagulants for specific high-risk patient groups, suggesting a potential shift towards antiplatelet agents in future management.
Abstract:
The thromboembolic rate of 768 patients who were treated only with aspirin after mitral valve replacement or mitral plus aortic valve replacement with porcine bioprostheses was evaluated. We analyzed the thromboembolic rate for the whole series and for subgroups of patients categorized by atrial fibrillation, giant left atrium, left atrial thrombosis, and dosage of aspirin (1 gm daily or 0.5 gm every 48 hours). The total embolic rate was 1.4% (11/768). No patient in sinus rhythm had an embolic event. The embolic rate for patients in atrial fibrillation was 1.9% (11/583). There were no embolic events in 31 patients with a giant atrium. An embolic event occurred in 1 of 42 patients with atrial thrombosis (2.4%). Patients treated with 1 gm of aspirin daily had a 3% embolic rate (9/295) while the incidence was 0.4% (2/473) in those treated with 0.5 gm every 48 hours (p less than 0.01). Administration of aspirin after mitral valve replacement with a bioprosthesis is a very effective treatment for prevention of thromboembolism. In our experience, this treatment provides protection equal to or better than that offered by oral anticoagulants for patients in atrial fibrillation as well as for patients with a giant atrium or atrial thrombosis at operation. The dosage and timing of aspirin administration may markedly affect the result of this type of treatment. Oral anticoagulation with coumarin derivatives may not be appropriate after mitral valve replacement with a bioprosthesis, and platelet antiaggregates should be used for this purpose in the future.