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Thrombotic and bleeding complications of prosthetic heart valves
1Department of Surgery, University of Pennsylvania, Philadelphia 19104.
Insights
Mechanical heart valves have higher risks of thrombotic and bleeding complications than bioprosthetic valves, especially in the aortic position. Warfarin anticoagulation is crucial for mechanical valves, while bioprosthetic valves offer better outcomes for pregnant women and children.
Area of Science:
- Cardiology
- Biomaterials Science
- Pharmacology
Background:
- Thrombotic and bleeding complications are significant risks associated with prosthetic heart valves.
- Bioprosthetic and mechanical valves have different complication profiles.
- Anticoagulation management is critical for valve performance and patient safety.
Purpose of the Study:
- To review and synthesize data on thrombotic and bleeding complications of bioprosthetic and mechanical heart valves.
- To compare complication rates between different valve types and positions.
- To evaluate the role of anticoagulation and patient-specific factors in managing these complications.
Main Methods:
- Systematic review of articles published since 1979.
- Analysis of linearized rates of thrombotic and bleeding complications.
- Comparison of outcomes based on valve type (bioprosthetic vs. mechanical), valve position (aortic vs. mitral), and patient demographics (pregnant women, children).
Main Results:
- Mechanical valves have higher rates of thrombotic and bleeding complications than bioprosthetic valves, particularly in the aortic position.
- Adequate warfarin anticoagulation is the most critical factor for mechanical valve safety.
- Bioprosthetic valves are preferred for women desiring pregnancy due to lower fetal wastage rates compared to mechanical valves.
Conclusions:
- Prosthetic heart valve choice impacts complication risks; mechanical valves require stringent anticoagulation.
- Bioprosthetic valves demonstrate a more favorable risk profile in specific populations like pregnant women and children.
- Further standardization in reporting and follow-up is needed for more precise outcome comparisons.
Abstract:
A review of articles published since 1979 indicates that thrombotic and bleeding complications account for about 50% of valve-related complications in patients with bioprosthetic aortic and mitral valves and for approximately 75% of the complications in patients with mechanical valves. Although compromised by lack of standard definitions and by variability in reporting and follow-up, the data suggest that the linearized rate of both thrombotic and bleeding complications in patients with aortic bioprostheses is approximately half that for aortic mechanical prostheses (2% versus 4%), but is approximately equal for both bioprostheses and mechanical valves in the mitral position (approximately 4%), and for mechanical and bioprosthetic aortic and mitral valves in combination. However, linearized rates for fatal thrombotic and bleeding events are two to four times higher in patients with mechanical prostheses. The adequacy of warfarin anticoagulation is the most important factor affecting thrombotic and bleeding complications in patients with mechanical valves and over shadows the dubious importance of other phenomena such as atrial fibrillation and left atrial thrombus. Short-term warfarin anticoagulation or the use of long-term platelet inhibitors, or both, do not appear to reduce the incidence of thrombotic complications in patients with aortic bioprostheses but increase bleeding. For mitral bioprostheses, the postoperative use of warfarin for three months or aspirin indefinitely is as effective in preventing thromboembolism as long-term warfarin. Acute prosthetic valve endocarditis is associated with a 13 to 40% incidence of thrombotic complications. Likewise, the recurrence rate of cerebral emboli is high (20-30%) in patients with prosthetic valves who are not anticoagulated. Bioprostheses are strongly preferred for women who wish to bear children; fetal wastage occurs in 25 to 30% of pregnant women with mechanical heart valves who receive either warfarin or heparin, or a combination of the two. Heparin, however, greatly increases the risk of maternal bleeding. In children, the efficacy of platelet inhibitors without warfarin anticoagulation is unproven; nearly all serious strokes occur when warfarin is omitted; and permanent disability from warfarin-related bleeding is rare. All prosthetic cardiac valves initiate coagulation and affect the dynamic equilibrium between activated procoagulants and endogenous anticoagulants. Warfarin is the only available oral exogenous anticoagulant.(ABSTRACT TRUNCATED AT 400 WORDS)