Management of Patients Post-Mitral Valve Replacement (MVR)
Anticoagulation therapy is the cornerstone of post-MVR management, with mechanical valves requiring lifelong warfarin with a target INR of 3.0 plus aspirin 75-100mg daily, while bioprosthetic valves require warfarin for 3-6 months followed by lifelong aspirin therapy. 1
Anticoagulation Management
Mechanical MVR
- Warfarin anticoagulation: Target INR of 3.0 (range 2.5-3.5) lifelong 1, 2
- Aspirin: Add low-dose aspirin (75-100mg daily) to warfarin therapy 1
- Monitoring: Regular INR monitoring is essential as unstable INR is a risk factor for bleeding complications 3
- Risk factors: Higher thromboembolism rates with mitral versus aortic prostheses (2.4% vs 1.9% per year) 1
Bioprosthetic MVR
- Initial anticoagulation: Warfarin with target INR of 2.5 for at least 3 months and up to 6 months 1
- Long-term therapy: Aspirin 75-100mg daily after initial anticoagulation period 1
- Special considerations: Consider longer anticoagulation in patients with additional risk factors (atrial fibrillation, previous thromboembolism, LV dysfunction, hypercoagulable conditions) 1
Follow-up Evaluation
Immediate Post-operative Period (0-3 months)
- Monitor for early surgical failure and assess LV function 1
- Evaluate for valve thrombosis, which should be suspected in any patient with increasing shortness of breath or fatigue 1
- If valve thrombosis is suspected, confirm with echocardiography and/or cinefluoroscopy 1
Long-term Follow-up
- Regular echocardiographic assessment to detect:
- Late surgical failure
- Valve deterioration (especially for bioprostheses)
- Assessment of LV function 1
- For mechanical valves: Chronic surveillance of INR is necessary 1
- For bioprosthetic valves: Monitor for eventual structural deterioration 1
Exercise and Rehabilitation
- Submaximal exercise testing approximately 2 weeks after surgery to guide exercise recommendations 4
- Implement a multidisciplinary rehabilitation program with gradual progression of exercise intensity 4
- Most substantial improvements in exercise capacity occur between 1-6 months postoperatively 4
- Complete normalization of hemodynamics and myocardial function may take up to 12 months 4
Management of Complications
Valve Thrombosis
- Immediate transfer to a cardiac center with surgical facilities after administering 5000 U of heparin IV 1
- For obstructive thrombosis: Urgent/emergency valve replacement is the treatment of choice in critically ill patients without serious comorbidities 1
- Consider thrombolysis for critically ill patients with serious comorbidities or when surgical treatment is not immediately available 1
- For non-obstructive thrombosis in hemodynamically stable patients: Short course of IV heparin with close monitoring 1
Thromboembolism
- Thoroughly investigate each episode rather than simply increasing target INR 1
- Review quality of anticoagulation control
- Evaluate for new murmurs or muffling of prosthetic heart sounds
- Check for evidence of endocarditis, especially with recent infection 1
Special Considerations for Elderly Patients
- Higher operative mortality in patients >75 years (>14% in the US, >20% in low-volume centers) 1
- Consider risks versus benefits carefully in asymptomatic elderly patients or those with mild symptoms 1
- Surgical risks are reduced with MV repair versus replacement, but many elderly patients require concomitant CABG 1
Pitfalls and Caveats
- Dual-antiplatelet therapy alone is insufficient for mechanical valves and may lead to valve thrombosis 5
- Unstable INR and history of thromboembolic/bleeding events are major risk factors for bleeding complications 3
- Mitral position carries higher risk of valve thrombosis compared to aortic position (HR=15.07) 3
- Bioprosthetic valves have higher early postoperative stroke risk compared to mechanical valves (1.5% vs 0.4%) 1
- Avoid interruption of anticoagulation therapy, as this significantly increases thrombotic risk 2