Leading the Way for Mechanical Valves: Partnering with Patients in Their Anticoagulation Therapy

July 30, 2021

Every year in the United States, approximately 80,000 patients undergo aortic valve replacement and approximately 18,000 undergo mitral valve replacement.1,2 As surgeons, we routinely help our patients decide whether a mechanical valve or a bioprosthetic valve should be used to replace stenotic and calcified heart valves. Bioprosthetic aortic valves can be implanted without sternotomy or thoracotomy in many patients via transcatheter aortic valve replacement (TAVR), which has increased the number of aortic valve replacements in patients with aortic stenosis.3 However, bioprosthetic valves have the known disadvantage of structural valve deterioration, which limits the valve’s lifespan to 10-15 years and necessitates reoperation, which can increase the risk of associated operative morbidity and mortality.

Mechanical valves have the advantage of prolonged durability and require reoperation only when infection or blot clots compromise their function. However, patients with mechanical valves are placed on lifelong anticoagulation therapy that may increase their risk of bleeding if not managed appropriately.4 The surgeons in the Division of Adult Cardiac Surgery within the UPMC Department of Cardiothoracic Surgery are experts in both open surgical valve replacement and TAVR. We routinely perform valve replacements using either mechanical or bioprosthetic valves as best indicated for our patients, and we provide care postoperatively to establish each patient’s well-being. 

Current guidelines from the American Heart Association, which were revised in 2017, state that “the choice of type of prosthetic heart valve should be a shared decision-making process that accounts for the patient’s values and preferences and includes discussion of the indications for and risks of anticoagulant therapy and the potential need for and risk associated with reintervention.”5 The guidelines note that a “mechanical prosthesis is reasonable for patients less than 50 years of age who do not have a contraindication to anticoagulation” and that “a bioprosthesis is reasonable in patients more than 70 years of age.” 

Although valve choice is largely a matter of patient preference, data shows that patients younger than a certain age have better survival rates with mechanical valves. A pivotal study of more than 25,000 heart valve replacements performed over a 17-year period published in The New England Journal of Medicine found a survival advantage of mechanical aortic valves as compared with bioprosthetic aortic valves in patients under 55 years of age and a survival advantage of mechanical mitral valves in patients under 70 years of age.4 In a study of 828 patients over 50 years of age, we observed a similar survival benefit of mechanical mitral valves over bioprosthetic valves. Additionally, we found that the likelihood of hospital readmission up to five years after valve implantation was the same for patients with mechanical valves and patients with bioprosthetic valves, suggesting that an increased bleeding risk may not be imparted by anticoagulation after mechanical valve implantation in the current era or that increased risk does not manifest as either increased readmission or increased mortality.6,7 These studies support the use of mechanical valves in a significant number of patients despite the inconvenience of anticoagulant therapy.

Nonetheless, patients can be hesitant to agree to replacement with a mechanical valve because of the commitment to lifelong anticoagulation therapy. Warfarin therapy requires frequent monitoring initially and can convey a higher risk of bleeding, which may cause patients anxiety. It is our job as caregivers to place these risks and responsibilities in context, so the patient can make an informed decision. At UPMC, we believe that support for patients as they begin anticoagulation therapy postoperatively decreases anxiety and significantly improves care. An informed discussion on the details of postoperative warfarin management often puts the patient at ease and aids in valve-choice decisions. 

When we start patients on warfarin and discharge them after surgery, we monitor their international normalized ratio (INR) frequently, typically three times a week with the help of a nurse who visits the patient’s home to draw blood for the tests. Then, a nurse or advanced practice provider communicates with the patient every day, or every other day, to manage their INR in consultation with the surgeon. Although the surgeons in some centers delegate the task of INR management to the patient’s primary care physician or cardiologist immediately after discharge, the surgical team at UPMC stays involved for the first 30 days postoperatively until warfarin dosage is stable. We believe this improves continuity of care and increases patient satisfaction with their choice to receive a mechanical valve. 

As each patient’s INR is stabilized at the goal established by the care team, monitoring decreases to once a week or less. We help the patient transition from nurse-drawn blood checks to using the CoaguChek® monitor (Roche Diagnostics). Our patients have preferred this self/home monitoring, which allows them to control their therapy, similar to the use of a glucometer by patients with diabetes. This independence goes a long way toward ensuring their well-being. Stable patients rarely require changes in anticoagulation therapy, and if changes are needed, a clinic visit is not always necessary. 

Aging patients with bioprosthetic valves will likely end up facing repeat operations or transcatheter interventions for heart valve replacement. Valve-in-valve TAVR may be an option for many patients, but not all patients will be candidates because of anatomical considerations from the prior bioprosthetic valve. Additionally, patients need to be aware that their risk of atrial fibrillation increases significantly as they age. Atrial fibrillation occurs in nearly 10% of the population over 80 years of age, and warfarin therapy may be utilized to reduce their risk of stroke. If a patient already has atrial fibrillation, lifelong warfarin therapy may no longer be viewed as a barrier to implantation of a mechanical valve.

At UPMC, we are committed to providing outstanding patient care using the best medically indicated practices while respecting each patient’s preferences and putting patients first. For patients who require valve replacement, we engage patients in their care by providing education based on the best available medical evidence and thoughtfully oversee the postoperative transition to anticoagulation therapy and self-monitoring when replacement with a mechanical valve is deemed the best option.

To learn more about the UPMC Heart and Vascular Institute or to refer a patient, call 412-770-4949. 

References

1. Gammie JS, Chikwe J, Badhwar V, et al. Isolated mitral valve surgery: The Society of Thoracic Surgeons Adult Cardiac Surgery Database analysis. Ann Thorac Surg. 2018;106:716-727.

2. Tam DY, Rocha RV, Wijeysundera HC,Austin PC, Dvir D, Fremes SE. Surgical valve selection in the era of transcatheter aortic valve replacement in the Society of Thoracic Surgeons Database. J Thorac Cardiovasc Surg. 2019.

3. Culler SD, Cohen DJ, Brown PP, et al. Trends in aortic valve replacement procedures between 2009 and 2015: has transcatheter aortic valve replacement made a difference? Ann Thorac Surg. 2018;105:1137-1143.

4. Goldstone AB, Chiu P, Baiocchi M, et al. Mechanical or biologic prostheses for aortic-valve and mitral-valve replacement. N Engl J Med. 2017;377:1847-1857.

5. Nishimura RA, Otto CM, Bonow RO, et al. 2017 AHA/ACC focused update of the 2014 AHA/ACC Guideline for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Task Forceon Clinical Practice Guidelines. Circulation. 2017;135:e1159-e1195.

6. Kilic A, Bianco V, Gleason TG, et al. Hospital readmission rates are similar between patients with mechanical versus bioprosthetic aortic valves. J Card Surg. 2018;33:497-505.

7. Sultan I, Bianco V, Gleason TG, Aranda-Michel E, Navid F, Kilic A. Clinical outcomes and hospital readmission rates in mechanical vs bioprosthetic mitral valves. J Card Surg. 2019;34:555-562.