Tricuspid regurgitation (TR) has generally been ignored in the therapeutic algorithm of patients with heart disease. There are several reasons for that.
Perhaps the most common reason is that almost 90 percent of patients with severe tricuspid regurgitation (TR) have left-sided heart disease such as mitral valve disease or left ventricular systolic dysfunction. In these instances the TR is thought to be a bi-product of the left-sided disease and most therapies are directed at addressing the left-sided disease.
There is also no effective therapy in the treatment of tricuspid regurgitation. As a matter of fact the most prescribed treatment for this disease is a diuretic. This is in part because surgical literature has shown that patients with primary TR who undergo surgical repair/replacement have higher mortality as well as morbidity compared to other valvular therapies. As a result cardiologists are reluctant to recommend corrective surgery in patients with secondary TR unless the patient was undergoing surgery for another cardiac condition at the same time.
However, there has been a paradigm shift over the past few year in our approach to the treatment of severe TR. A major part of this shift is due to the proliferation of transcatheter techniques in the treatment of other valvular heart diseases such as mitral and aortic valve.
It is observed that patients do worse after transcatheter aortic replacement or transcatheter mitral repair if they have concomitant tricuspid regurgitation. This is in line with the data from the surgical literature. As a result, there is an explosion in device development for percutaneous treatment of tricuspid regurgitation to be done either alone or in conjunction with percutaneous treatment of other valvular heart diseases. Many feasibility trials are currently looking at safety of these devices and a few trials are either ongoing or starting to look at their efficacy.
Nevertheless, the road ahead from diagnosis to treatment of TR is certainly torturous and long and perhaps it will take many years for us to have a clear understanding of when and how to treat this disease entity.
For one, the timing of intervention to give the patient the best prognosis is poorly understood. In most surgical trials, patients had advanced disease at the time of the operation. It is postulated that intervention should be done earlier in the disease course to give patients the best prognosis. However, the exact timing for transcatheter intervention remains a point of discussion.
Currently surgical correction is considered in patients based on the annular diameter of the tricuspid valve. This might not be the best surrogate marker to assess the severity of tricuspid regurgitation effect on the right ventricle. Many other parameters are being investigated to determine the deleterious effects of TR on the right ventricule. Echocardiographic measurements such as right ventricular strain are among such parameters.
Longitudinal follow up of these parameters will make it more clear as to when to intervene in the disease process to obtain the best prognosis.
The other obstacle in the treatment of TR is the tricuspid valve’s anatomy. It is comprised of three unequal very thin leaflets, the anterior leaflet the longest and posterior leaflet the shortest. Its location and thin nature of the leaflets make echocardiographic imaging especially difficult during any transcatheter procedure.
Optimal intraprocedural imaging is essential in successfully treating the valve. The development of intracardiac imaging as part of the percutaneous devices currently being developed should alleviate some of this difficulty.
Finally, the proximity of other cardiac structure to the tricuspid valve should be taken into account while planning for transcatheter intervention. The right coronary artery is positioned to the lateral aspect of the valve and conduction system to the septal portion. Therefore, the risk of right coronary perforation or inducing conduction disturbance during the procedure should be taken into account. Obtaining a cardiac CT and meticulously evaluating the tricuspid valve and its relationship to other cardiac structures is of paramount importance prior to most percutaneous therapies.
Tricuspid valve pathology is perhaps the last valvular pathology to be addressed by transcatheter techniques. There are a lot of challenges ahead as outlined above. Perhaps that is why tricuspid intervention is one of the more exciting fields to be involved in at this time. Also, its treatment could be the most rewarding for the patients as well as physicians.
Watch our recent video presentation on Tricuspid Regurgitation.