A 44 year old manual labourer from a village in a developing country presented with progressive dyspnea on exertion of two years duration. Two months before presentation, he had stopped going to work because of his dyspnea. He was diagnosed to have a calcific mitral valve with severe stenosis (mitral valve area 0.8 cm2) and mild regurgitation. He had moderate pulmonary artery hypertension. His aortic and tricuspid valves were normal. He had no coronary artery disease and was in sinus rhythm. He was referred for valve replacement surgery. Should this patient receive a mechanical or a tissue valve?
Approach 1: Patient should receive a mechanical valve
Iqbal H. Jaffer and Richard P. Whitlock
McMaster University, Hamilton, Ontario, Canada
The choice of prosthesis type in patients with valvular heart disease should always be individualised. The treating heart team must weigh the concerns surrounding durability of bioprosthetic valves compared with mechanical valves and the need for lifelong anticoagulation required with mechanical valves. In general, guidelines recommend that patients under the age of 60 would benefit from a mechanical valve, and those over 70 would benefit from a bioprosthetic valve.
We would argue, in this context, that the most appropriate choice for this patient would be undertaking a mitral valve replacement with a mechanical prosthesis. This recommendation is based on two considerations: firstly, there is a high likelihood of failure of a bioprosthesis within an unacceptably short period of time, which would then necessitate a higher risk re-operation. Several studies have reported that this has an impact on patient-important outcomes such as mortality and valve-related complications. For example, it has been shown that that the implantation of a bioprosthetic valve in the mitral position in patients under the age of 65 when compared with a mechanical valve may increase long-term mortality by 50%. Freedom from valve degeneration in patients receiving a mechanical MVR compared with bioprosthetic MVR is nearly four-fold higher. Furthermore, assuming all other clinical scenarios remain the same, according to the STS calculator, the risk of morbidity or mortality more than doubles for a mitral valve re-replacement even within 10 years from approximately 5% for the index operation to over 12% for the first re-operation.
Secondly, there is high likelihood of needing long term anticoagulation in a patient with severe mitral stenosis due to the development of atrial fibrillation (AF). It is well reported that patients with mitral stenosis have enlarged left atria and the correlation of an LA size to the development of at least one episode of AF is reported to be between 45-75%. Furthermore, with moderate pulmonary hypertension the risk of development of AF is also high and thus, this patient will likely require long term anticoagulation within the future. We acknowledge the difficulty in managing long term anticoagulation of patients in rural settings; however, there have been significant advancements in this realm as well, with the use of pharmacist-led thrombosis clinics and point of care INR devices in the treatment of rural patient in developing countries.
In summary, we would strongly advocate for a mechanical valve in this patient.
Approach 2: Patient should receive a tissue valve
Shiv Kumar Choudhary
All India Institute of Medical Sciences, New Delhi, India
The patient is a 44-year old manual labourer from rural India. He needs mitral valve replacement for long standing, symptomatic, severe calcific mitral stenosis. His other valves are normal. While choosing the prosthetic valve substitute, several issues need to be taken into consideration. Important considerations are age of the patient; occupation of the patient; availability, cost, and monitoring of anti-coagulation; monitoring of valve function and other valve related complications; and possibility of re-operation.
A tissue valve appears to best serve the needs of this patient. Being a manual labourer, this patient is prone to repeated injuries and thus is at an increased risk of life-threatening haemorrhage due to anticoagulants that are mandatory with a mechanical valve. As the patient is a resident of a village, he is unlikely to have access to a health facility where his anticoagulation status can be reliably monitored. A mechanical valve also requires frequent assessment with cinefluoroscopy/echocardiography. In a rural set up these facilities are unlikely to be available. In addition to the costs, the patient will be required to travel frequently to a town/city for these investigations. This will keep him away from work that will adversely impact his already compromised economic status and burden him further.
In a previous study from our institute, we have clearly shown that in a vast country like India where the majority of the population is based in rural areas, use of bioprosthesis eliminates the risks of sudden prosthetic valve dysfunction and death, reduces the risk of anticoagulation-related haemorrhage, avoids repeated visits to the hospital, reduces the costs of treatment and is associated with an acceptable quality of life. Even when bioprostheses are implanted in patients as young as 40 years of age, there is no difference in actuarial survival, thromboembolism, infective endocarditis, paravalvular leak, structural deterioration and valve related dysfunction when compared to mechanical valves. The average life expectancy in India for males is around 67 years and the tissue valve in this patient is expected to last for 10-12 years. He can safely undergo a re-operation once there is valve deterioration later in life.